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ECO-CHRONICLE, Vol.4., No. 3.September 2009, pp: 135 - 140

ISSN: 0973-4155

THE PROBLEM WITH PADDY CROP MIMICS - ECHINOCHLOA COLONAAND ECHINOCHLOA CRUS - GALLI IN NORTHERN TELANGANA,

ANDHRA PRADESH, INDIA

Ramana, Y.V 1., Pratap Reddy, N 2., Maruthi Rao, A 3. and Vatsavaya, S. Raju 2

1Govt. Junior College, Nekkonda, Andhra Pradesh2 Centre for Biodiversity and Biological Invasions, Department of Botany

Kakatiya University, Warangal, Andhra Pradesh3Department of Botany, Telangana University, Nizamabad, Andhra Pradesh

Corresponding author: satyavatsa@yahoo.co.in

ABSTRACT

Echinochloa colona and Echinochloa crus-galli are known crop mimics and problematic weeds ofthe paddy fields all over the tropics. The Echinochloa weed problem and economic losses inAndhra Pradesh, India, were investigated by taking up the districts of Karimnagar and Warangal innorthern Telangana. In Karimnagar district alone, the estimated paddy yield loss exclusively due toEchinochloa colona infestation was 2.423 q/h. The study reveals that the seed dispersal of thesecrop mimics is by water, air, cattle dung, FYM, seedling transplantation, etc. The seed output, seedweight, germination rate, dispersal methods and crop mimicry are found to be of immense economic,ecological and evolutionary significance in the success story of these weeds.

Key words: Paddy fields, Echinochloa species, crop mimicry, seed out put, seed germination,economic loss.

INTRODUCTION

In agro-ecosystems, any plant growingother than the crop sown is a weed. So,weed is a plant without place in an artificialecosystem. But, weed is an integral part ofthe biotic community of each and every agro-ecosystem as competitor with theassociated crop for most of the abioticrequirements for the growth andreproduction (Rao, 1983). Of all crop pests,weeds have the greatest potential to causeyield loss (34%), with actual losses in 2001-2003 of c. 10% worldwide (Oerke, 2006).Agricultural weeds, selected by human cropcultivation, are a relatively recent ecologicaland evolutionary phenomenon. Within aregion, agricultural landscapes canpotentially vary at a much finer spatial (fieldto field) and temporal (year to year) scale

when diverse crop and weed managementis practiced (Neve et al., 2009). During thesurvey of weed infestation patterns andprocesses in Telangana region of AndhraPradesh, the authors found the incidenceof two crop mimics in the paddy fields ofKarimnagar and Warangal districts. Theyare Echinochloa colona (L.) Link and E.cruss-galli (L.) Beauv. So, it has becomenecessary to study the reproductive capacity,seed characters, seed germination, etc. toknow: (i) the potential of these weedsaffecting the crop productivity and (ii) tocontrol the incidence of these weeds.

MATERIAL AND METHODS

(i) Seed weight and volume

For the determination of average weight, 100

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assorted cayopses (hereafter seeds is usedin the text, not in the literary sense) weretaken from rice fields of Jammikunta regionin Karimnagar district. They were weighedon a cal-on electric (single pan) balance.Three sets were considered. The averageweight of a single caryopsis was calculated.The ‘volume’ was measured bydisplacement method (Pandeya & Bhan,1966). For this, one hundred assortedseeds were immersed in water in ameasuring cylinder. The amount of waterdisplaced was fractioned by 100 to obtainthe average volume of one seed.

(ii) Seed output and reproductive capacity

Seed output of Echinochloa colona wascalculated by counting the number of seedsper inflorescence (compound spike) andtotal number of inflorescences per plant. Atotal of 25 plants were studied. Seed outputwas calculated according to Pandeya &Bhan (1966) as follows:Average number of seeds per inflorescence

= xAverage number of inflorescences per plant = y Average seed output per plant = xy

Similarly, the reproductive capacity wascalculated (Pandeya & Bhan, 1966) as:

Reproductive capacity = Average seedoutput x Average percentage of germination/ 100.

(iii) Seed germination

The germination rate was observed in potexperiments. Twelve earthen pots (30 cmdiameter and 25 cm height) were selected

and each filled with 30 kg soil collected formrice fields of Waddepalli village in Warangaldistrict. The soil was clay loam with pH 8.1,low in organic carbon and availablenitrogen, and medium with availablephosphorus and potassium. Theexperiments were laid out in split designand replicated thrice.

RESULTS AND DISCUSSION

The crop losses due to weed infestationswere calculated for various weeds in theregion by Ramana (2008). In the case ofthe grass weed cum crop mimic shambamillet -Echinochloa colona, the crop losswas estimated to be 2. 423 q/h (i.e. 6.45%).In the case of barnyard millet - E. crus-galli,the infestation of the paddy fields in theregion was negligible and hence the croploss was not estimated. The comparativeseed weight and volume, and length of theawn of the two Echinochloa species arepresented in Table 1.

Seed Germination

Echinochloa colona is a prime weed inmajority of rice fields of Warangal andKarimnagar districts of northern Telangana.Since the factors required for germinationof E. colona seeds are important, a detailedstudy on its germination was undertaken.Proper germination requires optimumtemperature, light of a particular wavelength, adequate moisture and presenceof oxygen in balanced proportions. All viableseeds germinated after a reasonable timeand normally developed into seedlings. Fordormant seeds, the dormancy has to bebroken for successful germination. Evenwhen they are not in dormancy, the seedsrespond differently to different externaltreatments in the laboratory under knownconditions of temperature and light(Pandeya and Bhan, 1966).

For every 15 days, the germination rate forE. colona and E. crus-galli was recorded.To confirm whether al l the seedsgerminated or not, 15 days time lapse wasconceived. The farmyard manure (FYM) inWaddepalli, Warangal region, was chosen

Particulars ofSeed

Echinochloacolona

Echinochloacrusgalli

Weight (g) 0.0004 0.0016Volume (ml) 0.01 0.04Length of awn(mm) - 2.30

Table 1. Seed weight, volume and length ofthe awn of Echinochloa species.

crus-galli

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where the cattle were fed with green grasscontaining E. colona seeds. Fresh dungwas collected in the early morning and wasthoroughly washed with water in a bucket.The seeds collected were air dried andstored in polythene cover, and usedimmediately for germination. Fifty assortedseeds were placed in the earthen pot. Thegermination rate was recorded 10 days aftersowing. The control was also setup withseeds collected from the nearby rice fields.The pots were arranged in split blocksdesigned, and were maintained intriplicates.

DISPERSAL OF SEEDS AND SEEDLINGS

(a) Estimation of seed in the rice fields

The weed seed survey of Echinochloacolona and E. crus-galli was carried out inKharif season in Jammikunta (Sites 1 and2) and Waddepally (Sites 3 and 4) in theprivate rice fields to know the weeddistribution after harvesting the crop. Fordetermining the seed spread, one squaremeter area (quadrat) was selected atrandom and the surface soil was collectedfrom it to be drowned in a bucketful of water.The seeds floated were collected, air driedand counted (Table 2). The seeds ofE. colona and E. crus-galli were identifiedon the basis of differences in size andshape.

Number of seeds found / m2Echinochloa speciesSite 1 Site 2 Site 3 Site 4

E. colona 1017 801 747 1877E. crus-galli 62 25 37 50Ratio E. colona / E. crus-galli 16:1 32:1 20:1 38:1

Table 2. Seeds found from rice fields per sq-1 m in the sites of JammikuntaKarimnagar district) and Waddaepalli (Warangal district).

Half the number of heaps in Jammikunta(Table 3) showed no seed presence ofeither of the species of Echinochloa. Of thethree heaps, two of them had the seeds ofboth the species of Echinochloa though thenumber is higher for Eichnochloa colona.The seed incidence ranged from 3 to 21.The heaps examined from Waddepalliregion had 33% seed infestation (2 out of 6heaps). Interestingly, only one showed theseeds of E. colona. However, the numberof Echinochola seeds found for 100 gm /FYM is 27 (more of E. colona 20/27).

Dispersal

Success in the establishment in a habitatand further spread depends upon thedissemination of seed (caryopsis here).The dispersal mechanism and theagencies causing the distribution of seedsand other reproductive propagules are theimportant aspects of an autecological study.

(a) Biotic Dispersal

By cattle, indirectly through FYM.

(b) Abiotic Ways (Wind and Water)

Echinochloa plants cannot be completelyeradicated by either herbicidal applicationor by hand weeding because it leads to thedisturbance to the root system of crop

Area/ Heap I II III IV V VI

Jammikunta EC 3ECG 0 Nil Nil EC 4

ECG 1EC 16ECG 05

Nil

Waddepally Nil EC 20ECG 7

EC 0ECG 3 Nil Nil Nil

Table 3. Seeds found in FYM at different heaps in Jammikunta and Waddepalli(seeds found from 100 gm / FYM).

EC = Echinochloa colona; ECG = Echinochloa colona crus-galli.

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plants. Hence, the weed plants which growin the rice hills are the major cause for furtherpropagation. At least, 5-7 plants ofEchinochloa colona remain in rice hills persq m area in the crop. Majority of seeds(95%) fall near the mother plants. Sincethese weed plants are not removed tillharvest time, all the seeds of such plantsfall in the rice fields as and when they ripe.In our surveys of Echinochloa infestations,the number of seeds deposited on theground after the crop harvest ranged from700 to 1900. Of these, many seeds areembedded at various depths in the soilwhich get hardened after harvesting. Theseeds again reach the top soil duringhoeing.

The seeds of Echinochloa are very light inweight (0.0044g) and spread in the fields insummer season by whirl winds. Intransplanted rice system, most of the time,the field is flooded with water. Echinochloaweed seeds float on the water and spreadfrom one field to other. The seeds whichreach farmyard through green fodder alsoget into manure through cattle faeces and/or at the time of cleaning farm yards.Ultimately, they reach the fields; they are afew numbers and exhibit low percentage ofgermination.

RESULTS AND DISCUSSSION

Echinochloa colona and E. crus-galli are theproblematic weeds of rice fields inTelangana region. When compared to E.colona, E. crus-galli infestation is far lessin the area. The study of seed output, seedweight, weathering grains, germination rate,etc. (Tables 1-3) revealed some interestingmechanisms which are of immenseecological significance in the life cycle ofthese successful weeds.

The average seed weight of E. colona(0.004gm) is much less than the weight ofE. crus-galli (0.01gm). This may be thereason for its wide spread through wind andwater in the field. Differences in weight arecorrelated to the buoyancy of fresh seeds ofthe two taxa. About 75% seed of E. colona

remained afloat up to 4-5 days and spreadall over the field. In the same period, 90%of the seeds of E. crus-galli drowned inwater. According to Yamasue et al. (1977)and Thompson and Grima (1979), thecharacteristic of small seeds of species isthat they persistent and dormant in seedbank, i.e. the soil. In E. colona, the seedsshatter at regular intervals as the seedsmature from the inflorescence. Hence, theseeds may be deposited in various depthsof the soil. In case of E. crus-galli, due tothe presence of awns, even though theseeds mature at various times they clutchtogether and do not last out frominflorescence as in the case of E. colona.

The reproductive capacity of a species isthe potential of species to reproduce itself.Seed output in a plant species dependsupon a number of environmental factors,viz. light, moisture, physiological stress(abiotic), disease, predation (biotic), etc.Besides, the seed production of a speciesbears a general relation to its ability toinvade. It is the product of the average seedoutput and the fraction represented by theaverage percentage of germination. Thisparameter is specific features of ecologicalimportance of a species (Pandeya & Bhan, 1966).

The seed out put in E. colona is 82,920 andthe reproductive capacity is 58,044. Theseed out put and reproductive capacity ofE. colona is higher than other grasses andsedges of rice fields. Conversely, it explainsits presence in rice fields in high density.The fresh seeds of E. colona and E. crus-galli collected from rice fields in Rabi seasonalmost failed to germinate in Petri dish (thegermination rate was only 4%) betweenApril-July. In the same months of thefollowing year, the germination rate was52% and 44% in E. colona and E. crus-galli,respectively in pots with soil underlaboratory conditions. It shows theimportance of edaphic factors. There maybe microbial or enzymatic actions on theseed. Pasic (1988) also reported influenceof microbial flora on seed germination andit was corroborated by Ramakrishna andKhosala (1971).

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Dormancy

In the present study, it was observed thatKharif and Rabi weed seeds do not exhibitany dormancy. Hence, the spread ispossible throughout the year in all cropfields. The maximum percentage of seedgermination for E. colona and E. crus-galliwas observed after 3½ months on seedmaturity. These seeds were colleted at theend of Rabi season (during June).Likewise, the mature seeds were collectedat the end of Kharif season (i.e. October)and the germination rate was observed.The maximum germination observed was72% in E. colona and 94% in E. crus-galli.In both the seasons, much fluctuation ingermination was noticed. The averagegermination rate in Rabi and Kharif seasonswas respectively 62.1% and 33% forE. colona and it was 65.5% and 54% forE. crus-galli. The germination of the seedscollected from cattle dung was foundreduced to 13.4%, against the control (60%).The objective of this observation was toknow the mechanical and chemicaldamages that occur to these weed seed inthe digestive track of the cattle. Thegermination of these seeds has obviouslylowered.

The FYM can be an important source ofdissemination of weed seeds because ofthe presence of viable weed seeds in dungas well as due to direct addition of matureseeds to compost pits as farm waste. Theseeds in FYM undergo further composting.The germination percentage of theseseeds was also observed. It was foundthat optimum temperature and acidityconditions prevail in compost pits. Theseeds retain viability to the extent of 9% inthe first month and up to 0% after twomonths. Even though a few seeds werefound and low percentage of germinationwas noticed for Echinochloa, they areadequate to continue the progeny in thefollowing year.

Since the farmers use FYM as organicfertilizer in June-July, there is only possibility

of Rabi weed seed germination. The Kharifweed seeds are embedded in the bottomof the compost pits for 8-9 months and loseviability. Harmon and Kein (1934) found 4%germination of Convolvulus arvensis seedsin FYM in first month and the seeds getdevitalized after four months. So, we mayconclude that seed germination rate inEchinochloa species is a complexphenomenon depending on various factorslike agroclimate, soil and biotic conditions.Infestation of Echinochloa is only possiblethrough its fruit cum seed, i.e. caryopsis.The seeds enter into f ields throughshattering from mother plant, FYM and byother means. By the time of harvest, mostof the weed seeds are shed from the motherplant at various intervals. Some seeds aresafely deposited in various depths of thesoil though many of them spread on thesurface. When examined, the surface soilafter harvest consists of 750-1950 viableseeds per square meter. It is also possibleto predict the weed problem by screeningthe surface of the soil, and can takemeasurements even before transplantation.Where there was no water logging, it wasvery interesting to note that Echinochloaseedlings appeared at an average of 158per 0.1sq-1m and 295 per 0.1 sq-1m area,respectively when counted on the fourth andtenth day of transplantation.

It was observed that many Echinochloaseeds float on the water and spreadthroughout the fields. Echinochloa colonaseedlings enter into the crop fieldssimultaneously with rice seedlings at thetime of transplantation. At the early stage,the labour/farmer could not recognize theweed plants due to the fact that the weed isa crop mimic. The experienced labour alsowill have no time and mood to separatethem. The farmers expressed that the weedis useful for their cattle which give more milkwhen fed on this grass while the calvesbecome fat. The dissemination of weedseedlings along with the transplanted riceseedlings in fields was noticed. Rao andMoody (1988) reported the presence of 271-683 weed plants per bundle, most of theseare sedges and broad-leaved weeds. In

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Jammikunta, on average, 4-6 plants ofEchinochloa were found out of 300 riceseedlings (0.1sq-1 m).

ACKNOWLEDGEMENTS

Thanks are due to the Head, Department ofBotany, Kakatiya University, Warangal forfacilities and the scientific staff (Dr Cheraluand others) of Acharya Ranga AgricuturalUniversity, Mulug Road, Warangal, forallowing the agricultural fields to be usedfor the Echinochloa weed experimentation.

REFERENCES

Harmon, G.B. and Kein, F.D., 1934. Thepercentage viabili ty of weed seedsrecovered with the faeces of farm animals.J. Amer. Soc. Agron. 29: 762-767.

Neve, P., Vila-Aiub, M. and Roux, F., 2009.Evolutionary-thinking in agricultural weedmanagement. New Phytologist 184: 783-793.

Oerke, E.C., 2006. Crop losses to pests.J. Agric. Sci.144: 31–43.

Pasic, M., 1988. Influence of seed microfloraon seed germination. Sumarstvo-I Prerada-drvesta (Yugoslavia) 4: 27-31.

Pandeya, H.K. and Bhan, V.M., 1966. Effectof row spacing and level of fertilization ongrowth yield and nutrient uptake of uplandpaddy and on associated weeds. Riso 15: 47-67.

Ramakrishna, P.S. and Khosala, A.K., 1971.Seed dormancy in Digitaria adcendenes(H.B.K.) Henr. and Echniochloa colonum(L.) Link. with particular reference to coveringstructures. Trop. Ecol. 12: 112-122.

Ramana, Y.V., 2008. Echinochloa WeedProblem in Rice Fields of NorthernTelangana, Andhra Pradesh. Ph.D. thesis,Kakatiya University, Warangal, India.

Rao, A.N. and Moody, K., 1988. Weed controlin rice seedling nurseries. Crop Protection7: 202-206.

Rao, V.S., 1983. Principles of Weed Science.Oxford and IBH Publishing Co., New Delhi.

Thompson, K. and Grima, J.P., 1979.Seasonal variation in the seed banks ofherbaceous species in the contrastinghabitats. J. Ecol. 67: 893-921.

Yamasue, Y., Sudo, K. and Ueki, K., 1977.Physiological studies on seed dormancy ofbarnyard grass (Echinochloa crus-galliBeauv. var. oryzicola Ohwi.). Proc. 6th Asian-Pacific Weed Sci. Soc. Conf. Indonesia 1: 42-51.

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SOIL EROSION AND RUNOFF MODEL FOR A WELL DEFINED SOIL SERIESOF TAMILNADU

Kurien, E. K.1 and Senthilvel, S.2

1 Kerala Agricultural University, Mannuthy, Kerala.2 Tamilnadu Agricultural University, Coimbatore, Tamil Nadu.

ABSTRACT

The present work was undertaken to study the soil erosion in terms of sediment delivery and runoff for Palathurai (Pth) soils, a well defined soil series of Coimbatore district of Tamil Nadu. Erosionstudies were conducted on micro soil loss plots of 3, 9 and 15 per cent slopes. The soil loss wasfound to increase with surface slope and surface flow rates. The runoff and consequently the soilloss were found to decrease with the duration of surface flow. Sediment delivery modelsincorporating the independent variables surface slope (S), inflow rate (F), and the time period (T)to the sediment delivery (Y) were developed by multiple regression analysis.Key words: Soil erosion, Runoff, Sediment delivery, Erosion model, Palathurai

INTRODUCTION

Soil and water are the essentialrequirements for sustaining life on earth.Unfortunately these resources arebecoming limited and crucial due to theexponential growth of population andurbanization. The soil and water resourcesare finite and need to be conserved for thefuture generations. Environmentaldegradation is becoming painfully evidentand steps are to be taken to reduce thecurrent degradation. In India, it is estimatedthat 175 million hectares of land is subjectto serious erosion hazards. In the State ofTamil Nadu, out of the total land area of130.058 lakh hectares, 58 lakh hectares areaffected by soil erosion problem. Erosionrates in India varied from less than 5 Mg ha-1yr-1 for dense forest to more than 80 Mg ha-1yr-1 in the Shiwalik hills (Gurmel et al.(1992). Soil erosion is a two-phase processconsisting of the detachment of individualparticles from soil mass and their transportby erosive agents such as running water

and wind. When sufficient energy is nolonger available to transport the particles, athird phase of deposition occurs. Key factorsinfluencing soil erosion are erosivity of thecausing agent and the erodibility of the soil(Morgan, 1986). The problems associatedwith soil erosion include the reduction ofsoil nutrients and thus a decreasedagricultural productivity and increasedturbidity of runoff water which in turn affectsthe quality of surface water andsedimentation of reservoirs (Owoputi andStolte, 1995). Richardson et al. (1983)developed a mathematical expressionrelating the daily rainfall amount (P) and theerosivity index (EI). Rai and Singh (1986)studied the runoff and soil loss on steephill slope varying from 0 to 100 per cent inMeghalaya. The runoff and soil loss wasfound to increase up to 21 per cent slopeand beyond this the soil loss and runoffdecreased steadily with increase insteepness of the slope. Sajeena et al.(2008) studied the erodibility of three welldefined soil series of Kerala under

ECO-CHRONICLE, Vol.4., No. 3.September 2009, pp: 141 - 146

ISSN: 0973-4155

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simulated rainfall conditions. Present studywas undertaken to study the runoff and soilloss characteristics and to develop a soilerosion model for a well defined soil seriesof Coimbatore district of Tamilnadu State,India.

MATERIALSAND METHODS

Micro soil loss plots were established tostudy the erosion process. Three micro soilloss plots of slopes 3, 9 and 15 per centand each with a size of 3x1.5 m wereprepared. The soil in the study area belongsto the series Palathurai (Pth). The soil isreddish brown and belonged to the texturalclass sandy clay loam (Sand 70%, Silt 10%and Clay 20%). The experimental set upconsisted of three units viz., runoff generator,the runoff plot and the runoff-sedimentcollection unit. The runoff generatordesigned and fabricated could apply thedesired rate of flow over the runoff plot. Thefield was brought to saturation by sprinklingwater uniformly over the area on theprevious night of the experiment day andwas kept covered by polythene sheet duringnight. The designed inflow rate of water wasapplied over the field using the runoffgenerator. The runoff samples werecollected from the runoff collection unit atspecif ic t ime intervals. The sedimentconcentration was determined byevaporating the water collected.

RESULTSAND DISCUSSION

Runoff studiesEffect of inflow rates on time distributionrunoff

The time distribution of runoff was drawnfor inflow rates of 0.2, 0.6 and 1.0 m3 h-1 at of3, 9 and 15 per cent surface slopes. Thetime lapse between the starting of the inflowand the production of runoff at the outlet wastaken as the init ial abstraction. Thedifference between the inflow and theoutflow is taken as the infiltration loss. Fig.1(a) shows the effect of inflow rates on runoffwith three per cent surface slopes. It wasobserved that at five minutes after the inflow

was allowed, the infiltration losses were 80,40 and 39 per cent respectively for inflowrates of 0.2, 0.6 and 1.0 m3 h-1. The finalinfiltration rates observed after 180 minuteswere 40, 23.3 and 35 per cent respectively.For the small inflow rate of 0.2 m3 h-1 thefinal infiltration rate decreased to 40 percent from the initial infiltration rate of 80 percent. The variation in the pattern of thechange in infiltration rates was due to thevarying pattern of ril l development atdifferent inflow rates and consequent flowconcentration through the rills. Constant rateof runoff was obtained after 165 minutes for0.2 and 0.6 m3 h-1 inflows and after 180minutes for 1.0 m3 h-1

From Fig. 1(b) it is evident that at 9 per centsurface slopes the infiltration loss was 80,35 and 32 per cent respectively for inflowrates of 0.2, 0.6 and 1.0 m3 h-1. The finalconstant rates of infiltration were 40, 21.67and 27 per cent respectively. The constantrates of runoff observed for the inflow ratesof 0.2, 0.6 and 1.0 m3 h-1 were 0.12, 0.47and 0.73 m3 h-1. Constant value of runoff wasobtained after 120 minutes for inflow of 0.2m3 h-1, after 150 minutes for inflow of 0.6 m3

h-1 and after 90 minutes for 1m3 h-1 inflow.According to Fig.1.(C), at 15 per cent surfaceslope, the initial abstraction was 70 per centfor inflow of 0.2 m3 h-1 and 32 per cent forinflow of 0.6 and 1.0 m3 h-1. The final constantrunoff values of 0.13, 0.55 and 0.87 m3 h-1

for inflow values of 0.2, 0.6 and 1.0 m3 h-1

were attained after 150,180 and 165minutes respectively.

Effect of surface slopes on timedistribution of runoff

Fig.2 shows the effect of surface slopes onrunoff at different inflow rates. For the inflowrate of 0.2 m3 h-1, the runoff recorded wasfound to increase with respect to increasein the surface slope. After a period of 120minutes from the beginning of the run, therunoff values at 9 and 15 per cent surfaceslopes remained constant. At 0.6 m3 h-1

inflow rate, the runoff pattern at 9 per centslope fol lowed a definite straight-linepattern. A sharp increase in the runoff was

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Regression coefficient Partial r2Name of thevariable

Additivemodel

Multiplicativemodel

Additivemodel

Multiplicativemodel

Surface slope (S) 0.2823 0.004 0.0310 0.00001Inflow rate (F) 5.1098 0.1565 0.0446 0.6470Duration (T) -0.2250 -1.0429 0.7361 0.0155Constant 28.99 532.6 - -Multiple R 0.86 0.81 - -

Table 1. Regression coefficients and partial correlation coefficients for the sedimentdelivery models

a. 3% slope

0

0.2

0.4

0.6

0.8

1

1.2

0 50 100 150 200Time elapsed, min

Run

off.m

3 h-1Inf low ,1m3h-1

1 m3h-1

Inflow ,0.6m3h-1

0.6 m3h-1

Inflow ,0.2m3h-1

0.2 m3h-1

b.9%slope

0

0.2

0.4

0.6

0.8

1

1.2

0 50 100 150 200

Time elapsed, min

Run

off,

m3 h

-1

c.15% slope

0

0.2

0.4

0.6

0.8

1

1.2

0 50 100 150 200

Elapsed time, min

Run

off,

m3 h-1

Figure 1. Effect of inflow on the time distribution ofrunoff

observed after 75 minutes for 15per cent surface slope and after120 minutes for 3 per cent slope.The rills were found to form muchearlier in the case of 15 per centslope. However the runoff for 9 percent surface slope remainedconstant without much variation asthe ri l ls developed at almostuniform rates only. For the inflowrate of 1 m3 h-1 the runoff curveswere distinct for all the surfaceslopes. The runoff valuesremained without much variationin the later stages. The findingswere similar to that of Rai andSingh (1986) who found that therunoff increased with slope up to21 percent and thereafter runoffdecreased with increase inslopes.

Soil loss studiesEffect of inflow rates on sedimentdelivery

The time distribution of sedimentdelivery was drawn for inflow rateof 0.2, 0.6 and 1.0 m3 h-1 for surfaceslope of 3, 9 and 15 per cent. Fig.3 shows the time distribution ofsediment at 3 per cent slope. Arapid increase in the sedimentconcentration was observed for thefirst 30 minutes for all the threeinflow rates of 0.2, 0.6, and 1.0 m3 h-1.

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a. 0.2 m3h-1

0

0.05

0.1

0.15

0.2

0.25

0 50 100 150 200

Elapsed time, min

Run

off,

m3 h-1

Inflow 3 % 9% 15%

b. 0.6 m3h-1

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0 50 100 150 200

Elapsed time, min

Run

off,

m3 h-1

c. 1.0 m3h-1

0

0.2

0.4

0.6

0.8

1

1.2

0 50 100 150 200

Elapsed time, min

Run

off,

m3 h-1

Fig.2. Effect of surface slope on time distribution ofrunoff

The maximum sediment concentrationswere 28, 32.5 and 36 kg m-3 for inflow of 0.2,0.6 and 1.0 m3 h-1respectively. The sedimentdelivery was found to increase up to theduration of 60 minutes and after that, itshowed a decreasing trend. After 135minutes, the sediment deliverycorresponding to the inflow of 0.2 m3 h-1 was3.5 kg m-3, whereas it was only 1.06 and 1.2kg m-3 for inflows of 0.6 and 1.0 m3 h-1. Thehigh rate of sediment delivery was observeddue to the pronounced rill developmentnoted during the experimentation time.Sediment concentrations in the outflow

reached minimum constantvalues after 165 minutes for all thethree inflow rates studied.

At 9 per cent surface slope peaksediment delivery of 40.36 and43.4 kg m-3 were reached after 45minutes for inflow rates of 0.6 and1.0 m3 h-1 (Fig.3b) respectively. Inthe case of 0.2 m3h-1 inflow rate,peak sediment delivery wasreached after 30 minutes. Asobserved in the case of 3 per centslope, in this case also there wasa rapid decrease in the sedimentdelivery for 60 minutes after thepeak rate was reached. Thereafterthe sediment delivery decreasedat slow rates. The constant ratesattained were 0.82, 1.01 and 1.2kg m-3 for the flow rates of 0.2, 0.6and 1.0 m3h-1 respectively. Thesediment delivery recorded wasfound to decrease with decreasein the inflow rate.

From Fig. 3.c. it can be seen thatat 15 per cent surface slope, peakrate of sediment f low wasrecorded after 45 minutes forinflow rates of 0.2 and 0.6 m3h-1.For the maximum flow rate of 1.0m3 h-1 the peak sediment deliveryof 52.86 kg m-3 was reached after30 minutes. The sediment deliverydecreased rapidly after the peakfor a period of 30 minutes and

thereafter decreased at slow rates. Itreached constant values of 0.78, 1.2 and1.31 kg m -3 after a time period of 165minutes for inflows of 0.2, 0.6, and 1.0 m3h-1

respectively.

Effect of surface slopes on sedimentdelivery

Time distribution of sediment delivery fromsurfaces of different slopes was studied.Fig. 4. (a, b, c) shows the effect of surfaceslopes on sediment delivery. The peak rateof sediment concentration in the runoff

145ECO-CHRONICLE

a. 3% slope

0

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increased with respect to surface slope forall the inflow rates studied. For an inflowrate of 0.2 m3 h-1, the peak sediment deliverywas 26.2, 38.2 and 38.26 kg m-3 at surfaceslopes of 3, 9 and 15 per cent respectively.At an inflow rate of 0.6 m3 h-1, the peak valuesof sediment delivery at slopes of 3, 9 and15 per cent were 32.5, 42.3 and 49 kg m-

3 respectively. The inflow of 1.0 m3 h -1

produced maximum sediment delivery forall the slopes. The peak rates of sedimentdelivery were 36, 48.2 and 52.86 kg m -3

for surface slopes of 3, 9 and 15 percent.

Sediment delivery model

A sediment delivery modelincorporating the independentvariables surface slope (S),inflow rate (F), and the timeperiod (T) to the sediment delivery(Y) was developed by multipleregression analysis using MSTATpackage. Table 1 presents theresults of the multiple regressionanalysis.

The multiple regressionequation yielded as,Y = 0.2823S + 5.1098 F – 0.225 T+ 28.99 (R = 0.86)where,Y = Sediment delivery, kg m-3

S = Surface slope, %F = Inflow rate, m3h-1

T = Duration of inflow, min

Positive correlation was found toexist between the sedimentdelivery and the independentvariables surface slope and theinflow rate.

A multiplicative sediment deliverymodel was also developed. Theresulted model could not give ahigher R2 value than the additivemodel. The model yielded is as:

1565.0

0429.1

004.06.532

T

FSY (R = 0.81)

It can be seen that the linear modelperformed better in the studied data range(S = 3-15 per cent, F = 0.2-1.0 m3h-1 and T= 0-180 min) but it fails to predict thesediment delivery when duration of inflowexceeded the study period of 180 min.Though multiplicative model has yieldedrelatively lower R value, it was capable ofpredicting the sediment delivery for thewider ranges of input parameters.

SUMMARY

The sediment delivery and runoff potentialof Palathurai (Pth) soils, a well defined soil

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Fig. 4. Effect of surface slope on time distributionsediment delivery

series of Coimbatore district of Tamilnaduwas studied. The soil erosion was found tobe directly related to the surface slope andamount of inflow over the land and wasinversely proportional to the time period ofsurface flow. Soil erosion modelsincorporating surface slope, inflow rate andtime period was attempted. An additive

model and a multiplicative modelwhich could predict the soil losswere developed. The R value forthe multiplicative model wasrelatively lower than that for theadditive model. The multiplicativemodel was capable of predictingsediment delivery for wider rangesof slope, inflow rates and timeperiod.

REFERENCES

Gurmel, S., Ram, B., Pratap, N.,Bhushan, L.S. and Abrol, I.P., 1992.Soil erosion rates in India. Journalof Soil and water Conservation, 47(1): 97-99.

Morgan, R.P.C., 1986. Soil erosionand conservation. LongmanScientific and Technical, England.pp. 12-15.

Owoputi, L.O. and Stolte, W. J.,1995. Soil detachment in thephysically based soil erosionprocess- a review. Transactions ofthe ASAE, 38 (4): 1099-1110.

Rai, R.N. and Singh, A., 1986.Effect of hill slope on runoff soilloss, nutrient loss and rice yield.Indian Journal of Soilconservation, 14 (2): 1-5.

Richardson, C.W., Foster, G.R. andWrite, D.A., 1983. Estimation of

erosion index from daily rainfall amount.Transactions of the ASAE, 26(1): 153-156.

Sajeena S., Abdul Hakkim and Kurien, E.K., 2008. Erodibility of three well definedseries of laterite soils in Kerala undersimulated rainfall conditions. Indian Journalof Soil conservation, 36 (2): 74-77.

a. 0.2 m3h-1

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147ECO-CHRONICLE

ECO-CHRONICLE, Vol.4., No. 3.September 2009, pp: 147 - 154

ISSN: 0973-4155

GROUNDWATER STATUS AND MANAGEMENT STRATEGIES IN RUPNAGARDISTRICT PUNJAB, INDIA.

Parul Virk1, Singh, K. P.2, Brar, K. K.3, Devender Dhanda1 and Nibedita ghosh1

1Department of Environment Science and Vocational Studies, Panjab University,Chandigarh.

2Department of Geology, Panjab University, Chandigarh.3Department of Geography, Panjab University, Chandigarh.

ABSTRACT

Growth in industrial, agricultural, and municipal sectors has resulted in increasing utilization ofwater, which has caused considerable pressure on the development and sustenance of waterresources, especially groundwater resources. In general, groundwater problems are due tocontamination, over exploitation or a combination of two. This article deals with the groundwaterstatus of Rupnagar district.

Rupnagar district covers an area of 1382 sq km and consists of five blocks and has shown atremendous change in industrial, urbanization and agricultural sector in the last four decades. In1960 agricultural sector covered only 43 per cent of the total geographical area of the district,which increased to 54 percent by the year 2005. The present land utilization pattern shows that netarea sown is 780 sq km while area under forest cover and land put to non-agricultural uses are 370and 140 sq km respectively. Irrigation in the district is mainly by tubewells and canals. The total areairrigated by canals is only 9% of the total irrigated area and rest 91% is irrigated by groundwater.Overexploitation of groundwater for irrigation in Rupnagar district has led to decline of water levelin two blocks namely Chamkaur Sahib and Morinda block as the water table in these areas has gonedown to 25.4 m and 24.9 m respectively. If the present declining trend is continued, water table inthese two blocks of the district would decline beyond the critical depth. The present study focusseson formulating strategies for effcetive water management of the area.Key words- groundwater management, Rupnagar district.

INTRODUCTION

Water, the most precious gift of nature andindispensable/vital for sustenance of lifenext to air, influence economical, agriculturaland industrial growth of a country. It is themost commonly used commodity and mostwidely distributed resource of the earth. Ithas been evident that the ancientcivilizations had mainly flourished alongperennial surface water resources i.e. riversand streams. These civilizations had beenwiped out mainly due to improper

management of water resources.

Improper management of water resourceshas resulted in water logging and soilsalinity in canal irrigated areas. Overexploitation of groundwater has created adangerous situation of declining waterlevels, causing failure of tubewells ordeepening of abstraction structures leadingto higher cost of pumping. If water table fellby one metre, a tubewell consumesadditional 0.4 KW of energy to draw sameamount of water as it drew before the levelfell (CGWB 1996).

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Punjab, having a land area of 5.03 mha, isheading towards groundwater crisis. As perPAU, Ludhiana (1999), in 432 mha area,groundwater was falling at the rate of 25 to30 cm every year. About 85 percent statearea had a falling water level trend. The areawith depth of water from 3 to 10m belowground surface has increased from threepercent in 1973 to 45 percent in 1994. It isfeared that tubewells will stop functioningwhen depth to water exceeds 15 mbgl andif the present rate of exploitation ofgroundwater continues, the existingpumping system wil l become nonfunctional.

Causes of groundwater Depletion andContamination.

Groundwater is an integral part of theenvironment, and hence cannot be lookedupon in isolation. There has been a lack ofadequate attention to water conservation,efficiency in water use, water reuse, groundwater recharge and ecosystemsustainability. The causes of low wateravailability in many regions are also directlylinked to the reducing forest cover and soildegradation.

Study Area

District Rupnagar in Punjab is a part of theKandi belt of the Himalayas and the alluvialplain of the river Sutlej covering an area of1382 sq. km. It is situated in north easternpart of Punjab state. Physiographically, thereare four main units: Siwalik hills, valleys,piedmont plains and alluvial/flood plains.Siwalik hills have general slope, rangingfrom 25 to 60 percent and most of the hillarea is under forests. The piedmont plaincovers large area with slope 1 to 6 percent,which is partly cultivated and partly underforests and wastelands. The alluvial/ floodplain is marked with the confluence of Sutlej

and Sirsa rivers, with 1 to 3 percent sloperespectively. Most of the area is undercultivation and is used for growing commonagricultural crops. The study area fallsunder semi arid (sub moist) and less hotzone of Punjab. It experiences two hot wetperiods (mid December to mid February andmid June to mid September). The meanannual rainfall in the district is about 862mm and major portion of it is receivedduring the monsoon season, with fewshowers during winter. The peak of thetemperature (39.6 °C) is observed duringthe months of June and January is thecoldest month with mean monthly.

In this area, out of five blocks, two blocksnamely Morinda and Chamkaur Sahib Blockis facing severe groundwater deletionproblems, due to overexploitation ofgroundwater for irrigation purposes.Location of the study area is shown in Fig Iaand Ib.

Data Base

The study is based on visual and digitalanalysis of satellite imagery of IRS/ID LISSIII, dated March 2005. Data on groundwaterlevel have been collected from waterResources Directorate, Punjab.

METHODOLOGY

Base Map for 1960 was prepared usingsurvey of India Toposheets. Land use landcover maps of the area have been prepared(1960 to 2005) on a scale of 1:50,000 bydigital analysis of IR/ID LISS III data usingArc GIS 9.1 software. Supervisedclassification was adopted for delineatingland use land cover classes. Five land useland cover classes viz. forest cover,agricultural land, waste land, water bodiesand builtup land were delineated. The dataare analyzed through appropriatecartographic and statistical techniques.

149ECO-CHRONICLEFig. 1a. Showing location of the study area on

map of Punjab StateFig. 1b. Showing block boundary of the study

area

Fig 2. Land use land cover of the year 1960 Fig 3. Land use land cover of the year 2005

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RESULTSAND DISCUSSION

Table 1 shows the Land use Land Covercategories of the district from 1960 to 2005.Results indicated that builtup category in1960 accounted only 2.25% of the totalgeographical area of the district, which gotincreased to 8.74% by the year 2005. Thisvast increase can be attributed to the risingpopulation growth, urbanization andindustrialization. Total area occupied by thewater bodies in 1960 was 17.58% of thetotal geographical area of the district, whichgot decreased to 9.28% by the year 2005because of drying up and diversion of riverbodies. Forest land in 1960 occupied

1960 2005Lulc CategoriesArea (ha) Area (%) Area (ha) Area (%)

Built up 3119.69 2.25 12083 8.74

Water Body 24295.9 17.58 12836.5 9.28

Forest 29482.5 21.33 26436.2 19.12

Wasteland 21653.1 15.66 12835 9.28

Cropland 59648.7 43.16 740089 53.55

Total 138200 100 138200 100

Block June 1975 Oct 1975 June 2005 Oct 2005

Ropar 6.75 6.11 17.65 16.66Nurpur Bedi 4.90 2.66 7.60 7.75Chamkaur Sahib 11.25 9.30 23.80 23.00Anandpur Sahib 4.31 4.02 14.05 13.66Morinda 5.73 5.33 18.47 18.45

Block June 1975 to June 2005 Oct 1975 to Oct 2005

Ropar -10.9 -10.55Nurpur Bedi -2.7 -5.09Chamkaur Sahib -12.55 -13.7Anandpur Sahib -9.69 -9.64Morinda -12.74 -13.12

Table 1. Land use Land cover categories of year 1960 and 2005

Table 2. Average water table level in Ropar District

Table 3.Water Table Fluctuation

21.33% of the total area, which gotdecreased to 19.12% by the year 2005because of conversion of this category intoagricultural, industrial purposes etc.Wasteland in the year 1960 holds 15.66%of the total land area of the district, whichgot decreased to 9.28% by the year 2005due to the conversion of this category intoother land use. Cropland in the year 1960occupied 43.16% of the total geographicalarea of the district, which got increased to53.55% by the year 2005 because ofbringing more land under agriculturalactivities. Fig 2 and 3 shows Land use landcover map of Rupnagar district in 1960 and2005.

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Groundwater Resources of the Study Area

The groundwater in the area occurs both inconfined and unconfined conditions. Thewater level varies from place to place and ingeneral follow the topography of the area.Water levels are deeper in the submountainous kandi tract and occur 26 to 20mbgl. In the rest part of the area, the depthto water varies from 2 to 25 mgbl. Thehydraulic gradient is steeper near the hillsand is gentle near the plains.

The water table of the study area has shownonly declining trends from 1975 to 2005 andgreatest decline is noticed in two blocks,Chamkaur Sahib and Morinda Block, wherewater table has gone 23.80 mbgl and 18.47mbgl from 1975 to 2005. This declining ratehas brought these two blocks under darkcategory, where further exploitation ofgroundwater resources is not possible.Major reasons being fast depleting waterbodies in the district and land use land coverchange which has put groundwaterresources under threat.

From 1965 to 2005, only decrease of watertable is noticed in the district as seen fromtable 2 and 3, due to over exploitation ofgroundwater resources for agricultural andindustrial purposes.

Management Strategies

Strategies for effective water managementcan be grouped into: (i) those that reducewater withdrawal, and (ii) those that increaserecharging of groundwater in different zones.

Reducing Water Withdrawal

Water withdrawal can be reduced by partlydiversifying to low water-requiring crops,and employing water saving productiontechnologies at a field or farm scale.

Crop Diversification

Large-scale adoption of rice-wheat systemhas been a major factor in over-exploitationof groundwater due to high ET requirements(60 cm for June 10 transplanted rice, and40 cm for wheat). Therefore, there is a needto replace this cropping system with lowwater requiring crops. In kharif, rice may bereplaced with cotton (55 cm), maize (46 cm),basmati rice (50 cm), pulses (40 cm), andoilseeds (45 cm); whereas wheat may bereplaced with raya (32 cm) and gram (30cm).

Water-Saving Production Technologies

These technologies include soil andagronomic management that save waterwithout a loss in crop yields, leading tohigher productivity per unit use of water(water use efficiency), viz., planting time,irrigation scheduling, irrigation methods,tillage and mulching. In addition, technologyof conjunctive use of saline groundwaterwith surface canal water will increasewater use eff iciency in water- loggedareas.

Irrigation Scheduling

Water economizing irrigation scheduleshave been developed that economizeswater use without any yield reduction (Priharand Sandhu, 1987). In rice, it has beendemonstrated that higher yields can bemaintained by irrigating the crop at 2-daydrainage interval after soaking-in of previousirrigation (after 2 weeks of continuousponding following transplanting). This helpsin saving of 8 irrigations to rice. The lastirrigation to rice should be given two weeksbefore harvest. Similarly, irrigating wheatusing a simple weather-based approachsaves 2 irrigations compared to 5-6

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irrigations at fixed growth stages.

Irrigation Methods

Water use efficiency in crops can beincreased by using water-saving irrigationmethods. For example, irrigationapplications in furrow in wide-row crops likesugarcane, cotton, sunflower and maizesave water without any yield reduction.Recent innovations of sprinkler and dripirrigation methods apply water without muchloss, and can irrigate 1.5 to 3.0 times areacompared to flooding for same amount ofwater. However, due to heavy init ialinvestment, their use is more profitable inhigh-value vegetable and horticultural crops.

Straw Mulching

Use of surplus crop residues as a mulchingmaterial in crops during summer monthsconserves water, reduces soil temperatureand controls weeds. Several studies havedemonstrated that mulching increasedyields of sugarcane, maize, sorghum fodderand potato. Mulching also saved 7-40 cmirrigation water for comparable crop yields.

Increasing Groundwater Recharge

In areas which face the problem of decliningwater tables, groundwater recharging canbe increased with surplus run-off wateravailable during rainy months throughfollowing measures.

Construction of Check Structures inDrains

A network of available surface drains canbe utilized for artificial groundwater rechargeusing surplus run-off water during rainyseason through canal networks(Khepar,2003). The recharging through

drains can be enhanced by constructingcheck structures across the drains atsuitable intervals to create pools for storageof water and digging bores in the drains upto the upper aquifer. Preliminary feasibilitystudies have already been conducted onthese aspects in Punjab. Cavity wells canalso be used for recharging duringmonsoon by taking appropriate precautionsnot to allow pollutants to go along with it.

Groundwater Recharging in Kandi Area

In Kandi area (annual rainfall of 1100 mm),a substantial fraction of rainfall (40 percent)becomes run-off during rainy season.Reduction in run-off to 20 percent byadopting different soil and waterconservation practices can provideadditional 0.1 million ha.m water annuallyfrom the monsoon rains that may increasewater table in central Punjab (Bhamrah,1998). These conservation measuresinclude construction of water-harvestingstructures, slope management throughterracing, land levell ing and contour-bunding, and soil management throughcontour and conservation tillage, mulchfarming.

Water Harvesting in the Shivalik Foothills

In the Shivalik foothill, most of the run-offwater of monsoon rains is transportedthrough seasonal streams. One way ofentrapping and utilizing this run-off water isto construct a series of small water-harvesting structures (WHS) in the form ofearthern embankments at appropriateplaces across these seasonal streams.

These structures not only store run-off waterfor providing supplemental/ life-savingirrigation, but also help in recharging ofgroundwater. There are about 120 small

153ECO-CHRONICLE

WHS in the Shivalik foothills under differentwatershed programs. Performanceevaluation of WHS constructed at Karoranin 1984 revealed that a substantial part ofstored water percolated to groundwater, andsupplemental irrigation during rabi seasondoubled crop yields (Sur, 2003).

Recharging of Groundwater by ExcavatingVillage Ponds

The village ponds, which once were usedfor storing run-off water have now becomea source of environmental pollution. Beforemonsoon, village ponds usually dries upand farmers took the excavation ofsediments for putting in their fields due toits high nutritive values. These excavationsincreased the infiltration of water fromponds to ground. But now because ofcontinuous ponding and no digging resultsin less infiltration and less recharging.

CONCLUSION

It can be summarized from this discussionthat the assessment of status of waterresources points towards a substantialwater deficit (demand-supply) in the state.

In order to maintain the agriculturalproductivity on a long-term basis, there isurgent need to reduce groundwaterwithdrawal, partly through cropdiversification and improving water useefficiency at a f ield scale as well asaugmenting recharging of groundwater withsurplus water. It is felt that the adoption ofavailable technologies for increasing wateruse efficiency at a field-scale will becomemore meaningful only when the farmers aremade aware of the harms of the wastefulexpenditure of irrigation water which is morecommon due to easy access ofgroundwater.

ACKNOWLEDGEMENTS

Authors would like to extend thanks toDepartment of Environment science anddepartment of Geology, Panjab University,Chandiagrh and Punjab Remote SensingCentre, Ludhiana for providing Laboratoryand library facilities to us.

REFERENCES

Central Groundwater Board, Ministry ofWater Resources, National PerspectivePlan for Recharge to Groundwater by utilizingSurplus Monsoon Runs off. CGWB.Faridabad Publication.1996.

Bhamrah, P.J.S., 1998.Conjunctive Use ofSurface and groundwater Resources forsustained Productivity in Irrigated areas-Problems, case studies and futureperspectives. National Seminar on watermanagement for Sustainable AgricultureProblems and perspectives for the 21st

Century. IARI, ICAR and IWRS. WaterTechnology Centre, IARI, New Delhi, April15-17.

Khepar, S.D. 2003. Integrated approach forcombating water table decline in rice-wheatsystem. In Water Management forSustainable rice-wheat production systemin Indo- Gangetic plains (Hira, G.S., Haer,H.S. and Chawla, A., eds.) Tech Bull. No. 1/2003 Department of Soils, PunjabAgricultural University, Ludhiana.

Prihar, S.S., and Sandhu, B.S. 1987.Irrigation of Field Crops- Principals andIndian Council of Agricultural Research, NewDelhi.

Sur, H.S. 2003. Water harvesting andwatershed development technologies in the

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Shiwalik foothills of northern India. In Watermanagement for sustainable rice-wheatproduction system in Indo-Gangetic plains

(Hira, G.S., Haer, H.S. and Chawla, A., Eds.).Tech Bull.No. 1/2003, Dept of Soils, PunjabAgricultural University, Ludhiana.

155ECO-CHRONICLE

ECO-CHRONICLE, Vol.4., No. 3.September 2009, pp: 155 - 160

ISSN: 0973-4155

TIME SERIES ANALYSIS OF RAINFALL AND HYDROGRAPH OFPIEZOMETERS IN RESPONSE TO CONTROLLING HYDROGEOLOGY IN A

SUB-BASIN, SOUTH INDIA.

Abdul Ashraf, K. M.1,2, Mohammed-Aslam M. A.3,4, and Santhosh, N.1,2

1 Groundwater Department, Kakkanad, Ernakulam, Kerala.2 Post Graduate and Research Dept of Geology, Government College, Kasaragod,

Kerala.3 Department of Civil Engineering, Government Engineering College, Thrissur, Kerala.

4International Academy for Graduate Studies, P.O. Box 3047, Ras Al Khaimah, UAE.

Corresponding author: ashrafkma@yahoo.co.in

ABSTRACT

Groundwater response to rainfall intensity has been investigated, in Perumba sub-basin, Kannur,Kerala, India. Multi-day rainfall induced flood events have also been analysed. The piezometric leveland recharge through rainfall showed their relationship for one entire monsoon period, whichoccurred over a few days in October 2002. Water level fluctuations in the piezometers of Perumbasub-basin provided an opportunity to understand the causative underlying mechanisms andcontrolling hydrogeological characteristics. The groundwater hydrograph with respect to precipitationrevealed that quick response of piezo surface indicates good connectivity with phreatic zone. Thecontrolling hydrogeologic set-up is reflected in the water-level pattern of peizometers in the hard-rock aquifers of sub-basin. The nature and extend of fractures and joints in the rock are generallycontrolling the occurrence and movement of groundwater and its level.Key words: Peizometer, Hydrograph, Rainfall, Aquifer

INTRODUCTION

Correlation of water-level and rainfallmeasurements yield good and reliableresults to model different catchmentslocated under varying climatic andgeological terrains. Hard rock terrain facesmany challenges in studying their hydrologyand water resources to better understandthe natural phenomena to form the basisfor effective management of theseresources. Significant advances haverecently been made about the hydrographstudies and functioning of hard rockaquifers, recharge mechanisms andaquifer models in watersheds. Thehydrodynamic properties of these aquifersappear to be mainly related to rechargerates, weathering processes and structures

present (Dawdy, 1972; Cluckie, and Owens,1987; Srinivas et. al., 1999; Gavrilenko et.al., 2000; Kumar and Ahmed, 2003; Chadhaet.al., 2005; Rolland et. al., 2005; Sun andCornish, 2005; Dewandel et.al., 2006).Hard rocks (igneous and metamorphicrocks) occupy large areas in many placesof south India. Their groundwaterresources are modest in terms of availabledischarge per well compared to those inother types of aquifers.

Geologically, the area of study comprise ofgneisses, charnockites, alluvium withlimited laterite. The general hydrogeologicalconditions are quite congenial for thestorage of ground water in tertiary formationsand weathered, fractured zones of crystallinerocks. Groundwater occurs under semi-

ECO-CHRONICLE156

confined or confined conditions in fracturezones in the crystalline rocks. Bore wellshaving yield ranging from 5000 to 12000lph are present along these zones. Wateryielding zones occur between 25 to 75mdepths. The area has humid climate withan oppressive hot season from March tothe end of May. This is followed by the south-

Fig.1 Location of study area

Study Area

Figure 2. Annual rainfall at Kankol rain guage station

west monsoon which continues till the endof September. October and November formthe post-monsoon or retreating monsoonseason. The north-east monsoon whichfollows extends up to the end of February,although the rain generally ceases afterDecember. During the months of April andMay, the mean daily maximum temperature

is about 350 Celsius.Temperature is low inDecember andJanuary, which isabout 200 Celsius. Oncertain days the nighttemperature may godown to 160 Celsius.

Water level f luctu-ations in thepiezometers of thePerumba sub-basin inKannur district, Keralastate, India inresponse to rainfalland the control l ingh y d r o g e o l o g i c a lenvironment has beenattempted in this study(Figure 1). Detailedobservations weredone at piezometers ofKNR-Pz224 (N12° 08'40" and E75° 18' 21"),KNR-Pz227 (N12° 13'27" and E75° 18' 58"),KNR-Pz229 (N12° 05'00" and E75° 15' 21")and KNR-Pz231(N12° 12' 00" andE75° 23' 13")respectively. Thispaper gives a detailedanalysis of theconfiguration ofhydrological system,dealing particularlywith the relationshipsbetween rainfal lpattern and water levelbehaviour.

157ECO-CHRONICLE

HYDROGRAPH ANALYSIS ANDDISCUSSIONS

The annual average rainfall in the study areais about 3745 mm with more than 80% of itoccurs during the period of south-westmonsoon. The rainfall during July is veryheavy and the district receives 68 per centof the annual rainfall during this season.The area of study receives one of the highestrainfalls in the state. The annual rainfalldata from 1990 to 2002 at Kankol is shownas Figure 2.

Monitoring has been done during themonsoon period of 2002 for thehydrogeological characterization. In the year2002, a 3773 mm of rainfall was recordedat Kankol rain guage station in Perumba(Pervemba) sub-basin. The ground waterhydrograph - rainfall relationship of thePeruvemba sub-basin was analysed withthe help of water level data recorded byAutomatic Water Level Recorders (AWLR)instal led in the dedicated borewells(piezometers) in five monitoring stationsestablished in this sub-basin. The loggeror pressure transdu- cers are installed atpurpose built borewells (monitoringstations) to acquire high frequency waterlevel data so as to monitor short termgroundwater regime changes. Thegroundwater level readings are recorded atevery six hours interval (4data/day). Waterlevel fluctuation with rainfall data for an entiremonsoon period in all monitoring stationsin the sub-basin, as multiple hydrograph ispresented in Figure 3.

Two types of hydrograph patterns areobserved in the Perumba sub-basin.Among all the data, three of the peizometers,namely KNR-Pz224, KNR-Pz227 and KNR-Pz229 behaved in a similar pattern and theyform the first group. Secondly, thepeizometer KNR-Pz231 showed a differenttrend in its hydrograph. Hence, as arepresentative sample for the first group,the hydrograph of KNR-Pz224 in responseto the precipitation is presented separately

in Figure 4. The hydrograph of KNR-Pz231is shown as Figure 5. The south-westmonsoon started in the first week of Juneand ended in first week of September andafter a short spell of non- rainy period thenorth-east monsoon started in the first weekof October and ended in first week ofNovember in 2002. 68% of the annualrainfal l receives during south-westmonsoon. The piezometric surface(groundwater level in the borewell) startedrising in June due to the recharge throughthe rainfall received during monsoon andreached the peak by August. The water levelremained more or less stable at its peakup to September. This was followed by aslight recession period. But in the middle ofOctober, the recession was abruptly brokenwhen an unprecedented heavy rainfalloccurred over a period of 24 hours. Theheavy rainfall during the subsequent dayshas resulted a flash flood in the low lyingareas of coastal plain in the district,especially at Kannur town and adjoiningareas. The record rainfall and subsequentflash flood had reflected in all groundwatermonitoring stations in the sub-basin. Theunprecedented rafinfal l lead to ful lsaturation of phreatic aquifer andsubsequently the water level in thepiezometers rose to 1.50 m below groundsurface. The groundwater level dropped tothe post-monsoon level of 6 to 10m bglwithin three to four days.

The quick response of piezo surface in allgroundwater monitoring stations,particularly the first group at Vellora (KNR-Pz224) indicates a good connectivity withphreatic zone. Hydrogeologically, theaquifers comprise of the first category mayhave intersected shallow fracturesimmediately below the weathered zones.The second category of groundwatermonitoring well at Thimiri (KNR-Pz231) wasan exception to this phenomena of quickresponse to rainfall. It showed a differentdegree of response to the precipitation. Thehydrograph at Thimiri monitoring stationshowed no response or little response to

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Figure 3. Multiple hydrograph of piezometers in Peruvemba sub-basin (2002)

Figure 4. Hydrograph with rainfall at Vellore (KNR-Pz224)

Figure 5. Hydrograph with rainfall at Thimiri (KNR-Pz231)

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the recharge through flood (Figure 5). Theexceptional behavior at KNR-Pz231 is dueto massive hard rock with high degree ofconfinement of water-yielding zoneintercepted by this well. The crystalline rocksmainly biotite gneiss in this area are lessweathered and lacking secondary porosity.

CONCLUSION

The groundwater hydrograph with respectto precipitation revealed that quickresponse of piezo surface indicates goodconnectivity with phreatic zone. Thecontrolling hydrogeologic set-up is reflectedin the water-level pattern of peizometers inthe hard-rock aquifers of Perumba sub-basin. The nature and extend of fracturesand joints in the rock are generallycontrolling the occurrence and movementof groundwater. The massive crystallinerocks mainly biotite gneiss at places in thearea are less weathered and lackingsecondary porosity. Hence bore wellslocated in gneissic terrain are usually lessfeasible or less productive. This is mainlydue to high degree of confinement of water-yielding zone intercepted by this well. Thenature of peak curve also indicates therecession of f lood water level. Thegroundwater level during post-monsoondeclined to the level of 6 to 10m bgl withinthree to four days. This indicates that theaquifer is fully recharged to saturated leveland the excess floodwater drained by sub-surface runoff.

ACKNOWLEDGEMENT

The authors are thankful to the PostGraduate and Research Department ofGeology, Government College, Kasaragod,and Groundwater Department, Kerala, Indiafor providing facilities. The first authoracknowledges special thanks to Sri. J.Pradeep Kukillaya, then Director, StateGround Water Department,Thiruvananthapuram, Kerala for hisencouragement and permission to publishthis paper.

REFERENCES

Chadha, R. K.,Srivastava, K., and Kuempel,H. J., 2005. Earthquake related changes inwell water level and their relation to a staticdeformation model for the seismically activeKoyna-Warna region, India, (ed. Rummel,F.), Rock Mechanics with emphasis onstress, Oxford &IBH Publishing Co, NewDelhi, pp:135–150.

Cluckie, I. D. & Owens, M. D., 1987. Real-time rainfall-runoff models and use ofweather radar information. In: WeatherRadar and Flood Forecasting (ed. V. K.Collinge & C. Kirby). John Wiley.

Dawdy, D. R., Lichty, R. W. & Bergmann, J.M., 1972. A rainfall-runoff simulation modelfor estimation of flood peaks for smalldrainage basins, US Geol. Surv. Paper no.506.

Dewandel B, Lachassagne P., MaréchalJ.C., Wyns R and Krishnamurthy N.S., 2006.A generalized 3-D geological andhydrogeological conceptual model ofgranite aquifer controlled by single ormultiphase weathering, Jl. of Hydrology,330(1-2), pp: 260-284.

Gavrilenko, P., Melikadz´e, G., Ch´elidz´e, T.,Gibert, D., and Kumsiashvili, G., 2000.Permanent water level drop associated withthe Spitak Earthquake: observations at LisiBorehole (Republic of Georgia) andmodelling, Geophys. J. Int., 143, pp: 83–98.

Kumar D., and Ahmed S., 2003. Seasonalbehaviour of spatial variabil i ty ofgroundwater levels in a granitic aquifer inmonsoon climate, Cur. Science, 84(2),pp:188-196.

Rolland Andrade, D., Muralidharan and R.Rangarajan, 2005. Pulse responses of anunconfined granite aquifer to precipitation–A recharge evaluation through transientwater-level fluctuation, Cur. Sci., 89(4),pp:67 -681.

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Srinivas A., Venkateswara Rao B.,Gurunadha Rao V. V. S., 1999. Rechargeprocess and aquifer models of a smallwatershed. Hydrological Sciences—Journal—des Sciences Hydrologiques,44(5), pp:681-692.

Sun H. and P. S. Cornish, 2005. Estimatingshallow groundwater recharge in theheadwaters of the Liverpool Plains usingSWAT, Hydrol. Process. 19, pp:795–807.

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HYDROGEOMORPHOLOGICAL MAPPING IN PARAVANAR RIVER SUB-BASIN, CUDDALORE DISTRICT, TAMIL NADU, INDIA.

Shankar, K., Aravindan, S. and Rajendran, S.

Department of Earth Sciences, Annamalai University, Annamalai Nagar,Chidambaram, Tamil Nadu.

Corresponding author: geoshankar1984@gmail.com

ABSTRACT

Hydrogeomorphology of the Paravanar river sub-basin, Cuddalore District, Tamil Nadu is mappedusing the remotely sensed satellite data of IRS P6 LISS-III based on image interpretation keys namelytone, texture, size, shape and associated features. The major hydrogeomorphological landformsare categorized as Tertiary upland, Flood plain, Alluvial plain, Coastal plain, Beach ridges, Sand-dunes and Swale. Among these, the Tertiary upland and flood plain are interpreted as goodgroundwater prospective zones. The hydrogeomorphology map prepared using satellite data showsthe distribution and extent of the ground water prospective zones. The interpretation of geology ofthe study area using satellite data reveals that the major rock types of the study area are ArgillaceousSandstones, Pebble bearing Sand Stones, Grits, Sand and Clays with Pebbles. Geologically alluviumand highly fractured sandstone are found to be good for ground water prospects. In Cuddaloresandstone, groundwater occurs under unconfined to semi-confined conditions and in alluvialformation, it occurs under unconfined condition. Tertiary Cuddalore formation and the recent alluviumare found to be groundwater prospective zones.Key words: Cuddalore Sandstone, Tertiary, Unconfined, Alluvium, Aquifer, Remote sensing.

INTRODUCTION

Water is an essential component of life andits availability has become finite as it needsto be replenishible by natural means. Theinterpretation of satellite data in conjunctionwith sufficient ground truth informationmakes it possible to identify various groundfeatures such as geological formations,structures and geomorphic features (Daset al. 1997) which may serve as direct orindirect indicators of the presence of groundwater (Ravindran and Jeyaram, 1997). Adetailed hydrogeomorphological mappingof an area can give a clear picture of thegroundwater resources and the associatedproblems of the area (Vaidyanathan, 1964;

Bhattacharya et al., 1979; Prithvi Raju, 1980;Milliongton et al, 1986; Sinha et al, 1990;Steven, 1991; Aravindan et al.,1996;Aravindan and Manivel, 2003). Severalstudies using satellite data have proved itsefficacy on coastal aquifers and landformassociated processes (Cracknell et al.,1982; Nayak and Sahai, 1983; Anonymous,1988; Gupta et al., 1989;Thamrongnavaswat, 1990; Nasir et al.,1990; Wagner, et al., 1991; Johannessenet al., 1993; Michalek et al., 1993; Hill et al.,1994; Ahmad and Neil, 1994;Rajamanickam and Loveson, 1998;Anbarasu and Rajamanickam, 1998;Ramalingam and Ranganathan, 1998).Anbarasu et al., (1999) have demonstrated

ECO-CHRONICLE, Vol.4., No. 3.September 2009, pp: 161 - 170

ISSN: 0973-4155

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in detail about the application of remotesensing data to demarcate the groundwaterprospective zones by means of identifyinghydrogemorphological features. Thepresent study is an attempt to evaluategroundwater potentiality of Paravanar sub-basin, Cuddalore district, India based ongeology and hydrogeomorphology usinghigh resolution IRS-P6 LISS IV remotesensing data.

Location of the study area

The Paravanar River Sub-basin lies in theCuddalore District of Tamil nadu statebetween longitude 11º18’ to11º45’ andlatitude 79º15’ to 79º45’ (Figure.1) of theSOI toposheets 58M/6, 58M/7, 58M/10 and11. The total area of Paravanar sub-basinis 880 sq km. It is bounded by Gadilam riverbasin on the north, Vellar basin in the southand Bay of Bengal on the east. Most part ofthe study area is a flat plain and sloppingvery gentle towards sea on east. The Redhills (Capper plateau) run parallel to the seawith an elevation of around 20 meters aboveMSL. The area has a tropical climate withthe highest and lowest temperaturesrecorded in June (43.30C) and January(10.40C), respectively. At the mine site, theaverage annual precipitation is 1369 mmwith 55% and 45% rainfall from the NE andSW monsoons, respectively (Khan et al.,2005). The precipitation of this study areamainly depends upon northeast monsoon,which is cyclonic in nature and attributed tothe development of low pressure in the Bayof Bengal. Area receives an annual rainfallof 1,162 mm (IMD, PWD, 2007). The studyarea includes three opencast lignite mines(Mines I, IA and II), associated with threethermal power plants that are operated byNeyveli Lignite Corporation Ltd. (NLC) andSTCM – LFPP STCMS – Lignite Firing PowerPlant at Uttangal, Neyveli-5.

Geology of the Study area

Paravanar river sub basin is mainly coveredby sedimentary formation and about 70%

of the basin area is occupied by Cuddaloresandstone of Tertiary age, consisting oflaterite, sandstone, clay, silt, sand, etc. Theremaining 30% of the basin area is coveredby river alluvium and coastal alluvium. TheParanavar river sub-basin is mainlyrestricted to the Tertiary and Quaternaryformations (Figure.2). The river Paravanaroriginates from the Cuddalore sandstoneof Tertiary age. This formation is completelycomposed of mottled argil laceoussandstone (Balasundar, 1968). TheCuddalore sandstone occurs at capperplateau, south of cuddalore town and ismade up of sandstone, clay and silt. Thelower Cuddalore sandstone isunconsolidated at few places. Thesandstones are found intercalated with claylenses and covered by lateritic formation(Selvaraj and Ramasamy, 1998). Thelateritic exposures are noticed in theNeyveli, Vadalur, North of Kurinjipadi, andNorth of Kullanchavadi regions. Thethickness of the Cuddalore sandstoneranges from 30m east of Vridhachalamtown to more than 500 m near to the coast.Alluvium overlies the Cuddalore sandstoneand comprises of sand, si l t and clay(Subramanian and Selvan, 2001). Itsthickness varies from 20 to 25 m near to thecoast. The Cuddalore sandstones covermostly the northern and western parts ofstudy area, while the alluvium covers mostlyon the eastern and southeastern parts ofParavanar sub-basin. The Tertiary andMesozoic sequence form E-SSW belt alongthe east coast of Tamil Nadu,unconformably rest over the Archaean rocksin the west. Few outliers of the sedimentaryrocks over the Archaean basement havebeen noticed. The borehole data(Subramaniam, 1970) indicate a thicksequence of sandstones, sands, clays andgravel down to a depth of 300 m in andaround the mine cut. Clay occurs asinterbeded impermeable formation inbetween overlying lignite and underlyinggrandular sandy formation. Where ever clayformation is absent, underlying sandyformation are subjected to direct recharge

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Figure.1 Location Map of the study area

Figure.2 shows the geology of study area

Figure 1.Location map ofthe study area

Figure 2.Geolohy of thestudy area

Figure 3.Geomorphologyof the studyarea

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from the overlying catchment area. Themajor soil types found in this basin areInceptisol, Entisol, Alfisol and Vertisol.

METHODOLOGY

Methodology adopted here is visualinterpretation of remotely sensed IRS P6LISS-III data to demarcate variousgeomorphic units on the basis of imageinterpretation elements such as size,shape, texture etc.

RESULTSAND DISCUSSIONHydrogeomorphology

Geomorphology is the science of landformsand it is an inter relative description of relieffeatures of the earth. Landforms developthrough the combined influence ofexogenous and endogenous process.Climate has a pronounced effect on thedevelopment of landforms. Space imagery

provides the best means of identifyinglandforms and process.

The geomorphology of the Paravanar Riversub-basin is interpreted using IRS-P6satellite data (Figure 3).Geomorphology ofstudy area shows gentle slope towardssoutheast and east, and is not drained byany major river except the ephemeralParavanar river flowing from west to east.This carries mine water and industrialeffluents with occasional natural water, anddischarge into the Walaja and Perumal lakeeast of the lignite mines. The hydrogeologyof the Neyveli Groundwater basin isextremely complex, consisting of a seriesof productive, confined aquifers below thelignite seam in both Mine I and II areas, whilea semi-confined aquifer lies above theseam and occurs only in the Mine II area.The geological study of the area reveals thatthe major rock types are Argillaceoussandstones, pebble bearing sand stones,

SlNo

Geomorphicunits

Lithology Description Groundwaterprospects.

1 Tertiaryuplands

Mainly laterites cappingover Digeneticsediments,

Occupying elevated land, mediumto coarse texture with lessdrainage density.Infiltration and permeability aregood. Prone to erosion.

Good.

2. Floodplain

Primarily comprises ofunconsolidatedmaterials like gravels,sand and silt.

A flat surface adjacent to streamcomposed of unconsolidatedfluvial sediments. Permeability isgood.

Moderate togood.

3. Buriedchannel

Comprises ofunconsolidated materiallike gravels, sand andsilt.

A linear low lying surface parallelor in connection with the existingriver or streams. Intensivecultivation practices are seen.

Very good.

4. BeachUn consolidated sand /silt deposited by tidalwaves.

Narrow stretch of unconsolidatedsand / silt deposited by tidal wavesalong the shore line.

Moderate.Quality isvariable

5. BeachRidge

Unconsolidated sand /silt.

A linear ridge of unconsolidatedsand / silt parallel to the shore line.Infiltration and permeability aregood in this landforms

Good.Infiltration andpermeabilityare good.

6. SandDunes

Sands of differentshapes and sizes

Heaps of sand of different shapesand sizes formed by wind action.

Good.Quality maybe varying.

Table 1. Characteristics of each geomorphic unit, lithology and groundwaterprospects of the units.

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Grits, Sands and Clays with pebbles.Pebble bearing sand stones and sandyformations in the study area are found to begood ground water bearing formations. Inthe Cuddalore sandstone, groundwateroccurs in unconfined, semi-confined, andconfined conditions; in the alluvium, itoccurs in unconfined condition. In the studyarea, both Tertiary Cuddalore Formation andthe recent alluvium form a potential aquifersystem (Jayaprakash et al., 2007). Themajor hydrogeomorphic features along thiscoastal tract comprises of upland plains,flood plains and coastal plains, are thegroundwater prospective zones. Thecoastal plain has a width of 6km. The rivercourse is almost gentle plain from apex ofthe basin to Bay of Bengal. The majorgeomorphological units interpreted andcategorised in the high lands of Tertiaryupland are i) Denudation Landforms:Tertiary Upland; ii) Fluvial Geomorphology:Alluvial plains, Flood plain; iii) CoastalGeomorphology: Coastal Plain, Beach,Beach ridges, Sand dunes and Swales.

i) Denudation LandformsTertiary Upland

In the west and northern side of the basin,upland of Tertiary age is occupied. Itoccupies nearly 70% of the basin. Tertiaryupland is the older sedimentarygeomorphic unit of this basin, having verygentle slope towards east, composed ofsands, ferruginous sand stone, gravels, clayand clay stones, popularly known asCuddalore sand stones, which is the mostpotential aquifer system of this basin. Thisgeomorphic unit can be observed in andaround Neyveli, Vadalur, Kurinjippadi,Kattugudalur areas. The eastern side of theunit boundary is bounded by Perumal Eri inthe east.

Here, the groundwater occurs in shallowphreatic aquifer, deep water table aquiferand perched water table aquifer. Presentday potential confined aquifers occur belowthe lignite bed which were once under

artesian condition around Neyveli. First twoconfined aquifers occur immediately belowthe lignite seams within the depth range of122mbgl and the third aquifer occursbetween 122m and 305 mbgl. This area ischaracterized by cashew plantation andprone to erosion.

ii) Fluvial GeomorphologyAlluvial plains

When the river attains old stage it loses allits energy to carry the bed load and depositsall the materials on either side of the riverand forms the alluvial plains. These areassociated with major streams/ rivers whichare identified by sparse surface drainage. Itis a level tract bordering a river on whichalluvium is deposited. Here thegroundwater occurs under phreatic andsemi confined aquifers in the alluvial areaof Pravanar river under Quaternaryformations.

Flood plain

When the river floods, it spills over on eitherbanks of the river and dumps lot ofsediments. Such flood plains expressremarkable tone in the images owing to themoisture influx and also due to thickvegetation. However certain rivers showdevelopment of such flood plains only onone side of the banks which indicate thepreferential shifting of the river in onedirection. Sometimes, rivers once have awide spread floodplain, subsequently eitherdue to depletion of incoming water or dueto latter rejuvenation, develops a narrow andrestricted flood plain i.e. younger flood plain.The younger flood plains are preferable forgroundwater prospects. Floodplains areconspicuous in this basin.

iii) Coastal GeomorphologyCoastal Plain

Coastal zone or coastal plain is a delicatetransitional zone situated in between landand sea. The coastal process develops the

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coastal geomorphic features as poly zonalin character. In the coastal plain, the majorgeomorphic agents are waves, currents andtides working in the back ground, definedby the structure of rock, climatic conditions,vegetation cover and man. Sea leveloscillations too have to be looked into forexplaining the coastal landform. Theshoreline of the study area is more or lesssmooth and curvilinear. The dominance ofnortheast monsoon is resulting in strongwave action in the direction of transverse /oblique to the shore. It has almost entirelyeliminated the protuberance and given walllike straightness to the shore (Ahmed, 1972).The presence of Oxbow lake andmeandering in the course of Uppanar andParanavar represents the low relief natureof the coastal plain. Some of the coastalgeomorphic units developed in this basinare exposed in the area of small hamletslike Pundiankuppam, Sangilikuppam andKudikkadu in the eastern side of the basin.

Beach

Beach and sand bars are the dominantdepositional landforms along the coast.Beaches develop in the gently sloping areasand they are the accumulation of atemporary deposit of sand, which aresubjected to erosion depending upon wave,tides and currents. Gravels and pebbles onthe shore are found between the low tidelevel and the coastline. Beachs grow in sizeduring the periods of less active wave attackbut may get destroyed by waves duringstorm. In this basin, beach is long, narrowand developed under active deposition.Silver beach, from little north of study area(Dhevanampattinum) to Cuddalore port (oldtown) is the second largest beach in TamilNadu, next to Marina, which stretch to a totallength of 4Kms.

Beach ridges

This land form is found to be very near tocoast in low tidal shorelines composed of

beach. Marine process with theintercalations of river deposits formedseries of beach ridges parallel to the coast,which is predominant. This indicates theemergence of coastal plain. A long narrowbeach ridge traversing from NE –SWdirection, passing through Mettupalayam,Mettur, Anaiyampettai, east of Karaikkaduand in Palvattunnam and Manikollai is observed.

High rate of sedimentation and landformsin the coastal plain suggests that thecoastal plain would have been under adeltaic plain of Paravanar. Marinedepositional landforms like beach ridgesand the sand dunes causes Uppanar rivercourse as the inter - dunal depression.Beach and the coastal plain of this riverbasin are now under severe alteration dueto its high ground water potentiality andproximity to the east coast and to thecuddalore port.

Sand dune

Along the beach ridges there are a numberof migrating and stabilized sand dunescomposed of sand parallel to the coast.Along the seashore, sand is brought fromthe shore face and backshore region bywave action. The sand located above sealevel is exposed to wind activity and sand isreworked into dunes (Renieck Singh, 1980).After the emergence of coastal plain, theaeolian action is intensified and sand dunesare formed. Some of the sand dunes arestill under migration while the others arestabilized due to vegetal cover. These typesof sand dunes are observed south ofThiruchopuram and east of Pettankuppam.

Swale

This is the land form in between the beachridges or the sand dunes. Such landform isobserved in west of Tachchanchavadi andeast of Karaikkadu.

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The characteristics of each geomorphicunit, lithology and groundwater prospectsof the units are described in the table 1.

CONCLUSION

The visual interpretation of IRS P6 LISS-IIIdata has provided information pertaining tohydrogeomorphology of Paravanar river subbasin, which is very useful in understandingthe nature and groundwater potentiality ofdifferent landforms. The integrated study ofgeological information is found to beimportant in preparing hydrogeomorphicmap. Various landform units like Upland,Alluvial plain, Coastal plain discussed aredue to the result of different geomorphicprocesses. The study has revealed thecapability of remote sensing technology forpreparing the hydrogeomorphological mapand evaluating the potential of study area.The study has shown the interrelationshipof hydrogeomorphic units, othertopographical features and their importancein demarcating the groundwater prospectivezones from Tertiary Cuddalore Formationto recent alluvium.

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analysis, ESCAPI/UNDP regional remotesensing programme (RAS 1 861 141),Beijing, China, pp.23-32.

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HYDROCHEMICAL STUDIES IN KAVARATTI LAGOON WATERS,LAKSHADWEEP ARCHIPELAGO

Udayakumar, P., Ajimon, V. J., Jean Jose, J. and Narendra Babu, K.

Chemical Sciences Division, Centre for Earth Science Studies,Thiruvananthapuram, Kerala.

Corresponding author: udayannair@yahoo.com

ABSTRACT

Studies were initiated to evaluate the water quality characteristics in the lagoon of Kavaratti atollwith special emphasis on semi diurnal variation in nearshore region. Water temperature and dissolvedoxygen were found higher in nearshore region of lagoon compared to the reef slope. It wasinferred that the lagoon water sustain a diverse and rich submerged flora represented inmajority by macrophytes by the increased utilization of nutrients. This floral enhancement isactively engaging in the nutrient cycle within the lagoon system. There is a growing evidence ofinflow of nutrients from outside sources, that is directly resulting in a detectable change in the lagoonecosystem, having low coral cover and high algal abundance.

Key words: Water quality, Semi diurnal, Nutrients, Lagoon, Kavaratti

INTRODUCTION

Coral reefs are one of the most productiveand diverse ecosystems in the sea (Birkeland1997).Shallow tropical coral ecosystemsacross the world are experiencing a numberof stresses that tends to threaten theirsurvival (Pandolfi et al. 2003, Lapointe et al.2004). The stresses associated with coralreef decline includes poor water quality(Boyer and Jones 2002), overfishingchanges in water temperature above andbelow coral local threshold(Dustan,1999).The above factorsexacerbate frequency of coral diseases,bleaching and algal overgrowth (Pattersonet al. 2002, Koop et al. 2001, Houghguldber1999) . The Lakshadweep islands inArabian Sea of India are typical atolls,formed by constant deposition of corals.These coral reef habitats are of greatecological and socio-economic importance

to the Lakshadweep islands in terms of itsrich biodiversity, productivity, anduniqueness, besides protecting it from theravages of the sea (Bakus et al.1993).According to recent study by researcherson coral reefs in the Lakshadweep group ofislands, it was observed that there was adecline in percentage of live corals andestimated that about 1.2 million litres of wasteper day is generated at Kavaratti alone whichfinally ends up in sea. Therefore it is vital tounderstand the water chemistry in lagoonwaters which will endow with valuablesuggestions for environmental stewardsinvolved in the conservation of coralecosystems in the Kavaratti Island. Further,recently published reports on the waterquality of Kavaratti lagoon waters are scanty.The objective of the present study is toevaluate the hydro chemical characteristicsof lagoon waters in Kavaratti atoll.

ECO-CHRONICLE, Vol.4., No. 3.September 2009, pp: 171 - 178

ISSN: 0973-4155

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MATERIALSAND METHODS

Study Area

Kavaratti, a perfect atoll (Gardiner, 1906) isan island of the Lakshadweep archipelago,located along lati tude 10 o 33 / N andlongitude 72o36/ E.The lagoon of the atoll isoriented in a north south direction, with theisland on the east and coral reef on the west(Fig.1).It is approximately 4,500m long,1,200m wide with an average depth of2m.The transport of water from sea tolagoon is always maintained by the actionof surf which breaks across the reef.

Studies on the hydrographical conditionswere made. Samples were collected fromnear shore of Lagoon (0.6m depth), whichincluded a semi diurnal study in whichsampling started from 06:00 hrs to 18:00hrswith a time interval of three hours. Two moresampling points were also covered insidethe lagoon which included lagoon centre(0.5km from the shore, 1.1m depth) andlagoon reef (1.1km from the shore, 1.8mdepth). The surface water samples werecollected using clean plastic bucket. Thefiltered samples (through 0.45µm Milliporefilter paper) were stored in polythene bottles,under refregeration for subsequent nutrientanalysis. Hydrographical parameters likesalinity, pH, and water temperature weremeasured in situ using standard probe.Dissolved oxygen was chemicallyestimated by Winkler method. Nitrite-N,Nitrate-N, Ammonia-N, ReactivePhosphates, Inorganic Sil icate, TotalNitrogen, Total Phosphorus were analyzedas per standard procedure (Grasshoff,1999). Absorbance was measured using adouble-beam spectrophotometer(Shimadzu, UV-150). The statisticalpackage SPSS 11.0 was employed tocompute Simple Correlation Matrix todetermine the similarity between waterquality variables.

RESULTSAND DISCUSSION

The variation in physico-chemicalproperties of the lagoon near shore, centre,

reef waters of Kavaratti atoll are presentedin Figure 2. For meaningful conclusions acorrelation matrix is produced to investigatethe relationship among the water qualityvariables and is presented in Table 1.Kavaratti lagoon is characterized by itsshallowness with an average depth ofabout 2m. Surface water temperaturesrecorded during the semidiurnal studyvaried from a minimum of 27.6oC at 06:00hrsto a maximum of 30.8oC at 15:00hrs. Watertemperature was found to increase with acorresponding increase in atmospherictemperature. Water Temperature and pHshowed highly signif icant posit ivecorrelation (P<0.01). This might be due tothe respiratory processes by benthic florain the lagoon, influencing thebiogeochemical processes of these waters(Sankaranarayanan, 1973). The decreasein temperature is limiting the uptake ofnitrate-N by photosynthetic community as itwas found to be inversely correlated withnitrate-N (P<0.05). It signifies that light isplaying a significant role in photosynthesis.The large-scale bleaching phenomenonand natural death of the corals all over thetropics have been related to rise in sea watertemperature by1-20 C due to global warming(Huppert and Stone, 1998). The surfacewater temperatures of the lagoon centre andreef was slightly higher compared to thesame in nearshore which may be attributeddue to high shallowness. Salinity valueswere found to be only slightly varied rangingfrom a minimum of 34.5 psu at 06:00hrs toa maximum of 35.6psu at 18:00hrs. Thisslight increase in salinity can be due to theevaporation of sea water with increase inambient temperature or due the transport ofwater from sea to the lagoon by waves whichbreak across the reef .Salinity values did notvary much in the lagoon as well as towardsthe reef.

Dissolved Oxygen concentrations variedfrom a minimum value of 3.63 mg l -1 at09:00hrs to a maximum of 8.46 mgl-1 at15:00hrs and in the reef it was recorded alow value of 2.86 mgl-1. In the present studyDO value was relatively high, especially after12:00 hrs, which is associated with high

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Figure 1. Map showing sampling location ofKavaratti lagoon

photosynthetic activity. The lagoon watersof Lakshadweep have been reported earlierfor lower densit ies of phytoplankton(Bhattathiri and Devassy, 1979). Theproductivity was confirmed by thesubmerged flora of seaweeds and seagrasses in the nearshore, while towardsthe reef slope this flora was totally absent.The enrichment of dissolved oxygen due tothis submerged flora, inspite of lowphytoplankton count, was well documentedfor Lakshadweep waters (Kaladharan et al.,1998). This also signifies that the rate ofgrazing was comparatively lower than thebiomass production of the dominantspecies in the lagoon area. Low DOconcentration observed in the reef slope canbe attributed due to hot period, lesssubmerged flora of macrophytes and higherrespiration rate. BOD values in lagoon werefound to be less than 3mgl-1 which indicates

that the region is not receiving anysignif icant organic pollutiondischarges. The BOD value of2.48mg/l observed at 06:00hrsare indicative of organicdischarges.

In the case of nutrients, Nitrite-Nconcentration varied from aminimum value of 0.13µmol/l at18:00hrs to a maximum value of0.35 µmol/l at 06:00hrs.Therewas a visible decrease in theconcentration of nitri te from06:00hrs onwards. According toSaantschi et al (1990), Chandranand Ramamurthy (1984), nitriteis often released into the wateras an extracellular product ofplanktonic organisms. Nitrite-N isfound to be inversely correlatedwith salinity (P<0.01) andpositively with BOD (P<0.01).Maximum concentration of nitriteobserved at 06:00hrs can be dueto the discharge of sewage in tothe water and the conversion ofNitrate-N to Nitrite-N can beanother factor for the increase.Due to the extremely porouslimestone structure of the island,

wastewater from onsite systems can bedetected in lagoon waters. Nitrate-Nconcentration varied from a minimum valueof 0.38µmol/l at 15:00hrs to a maximumvalue of 9.88 µmol/l at 06:00hrs. At 18:00hrsits concentration showed a slight increase.Nitrate-N was found to be negativelycorrelated (P<0.01) with salinity, this specifythat the additional source of nitrate isreaching inside the lagoon probably fromoutside the lagoon. The presence of floatingripened leaves carried by the wind from landcan be considered as one the major sourceof nutrients in lagoon. Nitrate-N was alsofound to be positively correlated (P<0.01)with Nitrite-N. Nitrite is the intermediateoxidation state between ammonia andnitrate, and as such it can appear astransient species by the reduction oroxidation of nitrate. The high concentrationof Nitrate-N observed at 06:00hrs infers

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Figure 2 a. Variation in Physico – Chemical properties of the lagoon waters ofKavaratti Atoll.

sewage water discharge as one of thesource. The concentration of ammonia wasmaximum at 06:00hrs and minimum valueof 0.04 µmol/l was observed at 12:00hrs.During the semidiurnal study, i tsconcentration pattern was irregular inlagoon waters. Ammonia is the chiefexcretory product of the marineinvertebrates, also is a nutrient which ispreferred over nitrate by the phytoplanktoncommunity in certain environmentalconditions. The above two factors affect theconcentration of ammonia in water (Olson,1980; Gilbert et al., 1982). Ammonium isalso known to be excreted by corals, whichis competitively removed by autotrophs andnitrifiers, then consecutively returned to

corals via photosynthate translocation oras ni tra te for assimi lat ion byzooxanthellae,without the N being lostfrom coral-algal symbiosis (Wafar et al.,1990). Total Nitrogen concentration variedfrom a maximum value of 11.97µmol/l at06:00hrs to a minimum value of 6.92 µmol/l at 15:00hrs, afterwards its concentrationstarted to increase. The decrease in TNconcentration coincided with decrease inthe inorganic nitrogen concentration duringthe same time period. This can be due tothe increased utilization of nitrogen by thephotosynthetic community. Inorganicphosphorus concentration varied from aminimum value of 0.048µmol/l at 06:00hrsto a maximum value of 0.24µmol/l at

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Figure 2 b. Variation in Physico – Chemical properties of the lagoon waters ofKavaratti Atoll.

18:00hrs. Further during the semidiurnalstudy, the concentration of inorganicphosphorus showed an i rregulardistribution. Total phosphorus showedminimum value of 0.51 µmol/l observedat 06:00hrs and a maximum concentrationof 1.73 µmol/l at 09:00hrs .The variationin concentration of Total phosphorusdidnn’t showed a similar trend as that ofinorganic phosphorus. The presence ofhigh concentration of Total phosphorus at09:00hrs shows the presence of domesticdischarges. Phosphate constitutes themost important inorganic nutrient that can

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Tabl

e 1.

Res

ults

of C

orre

latio

n an

alys

is o

n da

ta g

ener

ated

dur

ing

the

stud

y.

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l imit the phytoplankton production intropical coastal marine ecosystems (Coleand Salford, 1989). Phosphate is also animportant mineral deposit other thancalc ium carbonate in lakshadweepislands. Concentration of silicate didn’tshow marked variation, but it was foundto be negatively correlated with salinity(P<0.01) and positively correlated withnitrite (P<0.05) indicating that its sourceis from the land as sewage input. Towardsthe reef the concentration of nutrients was low.The abrupt decrease of nutrient concentration,particularly in the presence of light can beattributed to their utilization by macrophytes,particularly seagrasses and seaweeds, andlow retention by loose and unstablesediments (Sankaranarayanan, 1973).Further, nutrients are rapidly incorporated intoreef and plankton biomass (Laws andRedalje, 1979) which generally decreased tolow concentrations within 0.5 km from theshore. Seaweeds and sea grass detritusprovide natural sources of nutrients to coastalreefs and are indicative of productiveecosystem. Koop et al (2001) found thatincreased nutrients caused increasedmortality and reduced reproduction in corals.The increased nutrient flux to reef waters alsodrives algal blooms and shifts in communitycomposition (Lapointe 1999).

CONCLUSION

The surface layer of kavaratti lagoon ischaracterized by high dissolved oxygen,low nutrient contents and increased watertemperature. The clarity of water, highillumination owning to shallowness hasresulted in the thick growth of macrophytesparticularly seagrasses and seaweedsmaking the coral l ine ecosystemproductive. These macrophytes haveadorned the role of providing naturalsources of nutrients as well preventing theerosion of beaches. Towards the reef the waterwas less oxygenated and the standing levelsof nutrient were low. It is possible that a coral-dominated reef community exists. Thestatistical analysis applied to our datasetal lowed us to infer that there is aninfluence of land based sewage input in

the lagoon waters, finding its way throughthe extremely porous limestone structure aswell as from point sources (e.g., septicdischarges) which is being recycled within thelagoon system as there is no immediateflushing process by means of tides. If thisnutrient flux increases, there is chance forstresses, which can decrease coral coverand open substrate for algae to colonize.

ACKNOWLEGEMENTS

The authors wish to acknowledge Dr. M. Baba,Director, Centre for Earth Science Studies,Thiruvananthapuram and the Ministry of EarthSciences, Govt. of India for their help andfinancial support in this work. We also takethis privilege to express our grateful thanks toS&T, Kavaratti for their timely assistance andsincere thanks are also due to Dr. Baiju R.S,Sreejith M.I, CSD, CESS, Thiruvanantha-puram.

REFERENCES

Birkeland, C., In Life and Death of Coral Reefs(ed. Birkeland, C.), Chapman & Hall, NewYork.1997. pp: 536.

Boyer, J.N. and Jones, R, D., 2002. In theEverglades, Florida Bay and coral reefs of theFlorida Keys: An ecosystem sourcebook (eds.Porter, J.W. and Porter K.G.) CRC Press, BocaRaton, pp: 609-628.

Chandran, R. and Ramamoorthi, K., 1984.Hydrobiological studies in the gradient zone ofthe Vellar estuary, Mahasagar, 17(3), pp: 133-140.

Cole, C. V. and Sanford, R, L., 1989. Biologicalaspects of the phosphorus cycle, Proceedingsof symposium on phosphorus requirementsfor sustainable agriculture in Asia andOceania, March, Scope, UNEP, pp 6-10.

Dustan, P., 1999. Coral reef under stress:sources of mortality in the Florida Keys,Natural Resources Forum, 23, pp: 147-155.

Gardiner, J.S., 1906. In The fauna andGeography of the Maldives and Laccadive

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Archipelagoes (ed. Gardiner, J.S.).Cambridge Univ. Press, 2, pp: 1-1097.Gilbert, P, M., Goldmann, J, C. and Carpenter, E.J., 1982. Seasonal variation in the utilization ofammonium and nitrate by phytoplankton. InVineyard Sound, Marine Biology, 70, pp 237- 249.

Grasshoff, K., 1999. In Methods of SeawaterAnalysis (eds. Grasshoff, K., Kremling, K.and Ehrhardt, M.) ,Wiley VCH Verlag,Germany, p. 600.

Hoegh-Guldberg, O., 1999. Climate change,coral bleaching and the future of the world’scoral reefs, Marine and Freshwater Research,50 pp: 839-866.

Huppert, A. and Stone, L., 1998. Chaos in thePacific’s Coral reef bleaching cycle, AmericanNaturalist, 152 (3), pp: 447-459.

Kaladhran, P., Navas, K.A. and Kandan, S.,1998. Seagrass production in Minicoy atollof Lakshadweep Archipelago, Indian. J.Fish., 45 (1), pp: 79-83.

Koop, K., Booth, D., Broadbent, A., Brodie, J.,Bucher, D., Capone, D., Coll, J., Dennison, W.,Erdmann, M., Harrison, P,L., Hoegh-Guldberg,O., Hutchings, P., Jones, G,B., Larkum, A.W. D.,O’Neil, J., Steven A., Tentori, E., Ward, S.,Williamson, J., Yellowlees, D., 2001. ENCORE:The effect of nutrient enrichment on coral reefs.Synthesis of results and conclusions, MarinePollution Bulletin, 42 pp: 91-120.

Lapointe, B,E., 1997. Nutrient thresholds foreutrophication and macroalgal blooms on coralreefs in Jamaica and southeast Florida,Limnology and Oceanography, 42, pp:1119-1131.

Lapointe, B.E., Barile, P.J., Matzie, W.R., 2004.Anthropogenic nutrient enrichment ofseagrass and coral reef communities in theLower Florida Keys: discrimination of localversus regional nitrogen sources, Journal ofExperimental Marine Biology and Ecology,308, pp: 23-58.

Laws, E. A., Redalje, D. J., 1979. Effect ofsewage enrichment on the phytoplanktonpopulation of a tropical estuary, PacificScience, 33, pp: 129-144.

Olson, R. R., 1980. Sun - Shade adaptationsof a colonial Ascidians with a prokaryoticsymbiont, Am. Zool., 20, pp: 778.

Pandolfi, J. M.., Bradbury, R. H., Sala, E.,Hughes, T. P., Bjorndal, K. A., Cooke, R.G..,McArdle, D., McClenachan, L., Newman, M. J.,Paredes, G.., Warner, R.R., Jackson, J. B.,2003. Global trajectories of the long-termdecline of coral reef ecosystems. Science,301, pp: 955-958.

Patterson, K.L., Porte, J. W., Ritchie, K. B.,Polson, S. W., Mueller, E., Peters, E.C., Santavy,D.L., Smith, G. W., 2002. The etiology of whitepox, a lethal disease of the Caribbean elkhorncoral, Acropora palmata. Proceedings,National Acadademy of Sciences, USA, 99,pp: 8725-8730.

Sankaranarayanan, V. N., 1973. Chemicalcharacteristics of water around KavarattiAtoll.

Wafar, M., Wafer, S. and David, J.J., 1990.Nitrification in reef corals. Limnology andOceanography, 35, pp: 725-730.

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ECO-CHRONICLE, Vol.4., No. 3.September 2009, pp: 179 - 184

ISSN: 0973-4155

APPLICATION OF LIDAR REMOTE SENSING IN LAND DEGRADATIONMANAGEMENT

Balasubramani, K1., Parthasarthy, G.R1. and Alaguraja, P2 .

1 Departmemt of Geography, Madurai Kamaraj University, Madurai, Tamil Nadu2 Departmemt of Geology, Bharathidasan University, Trichy, Tamil Nadu.

Corresponding author: geobalas@gmail.com

ABSTRACT

Light detection and ranging (LiDAR) provides accurate information of the terrain and topography,even beneath the tree canopy and is extremely important to natural resource managers particularlyfor the management of land degradation. Scientifically, the main attributor to land degradation is soilerosion and vegetation cover changes. To analyze the soil erosion and vegetation cover changes,both Digital Terrain Model (DTM) and biomass computation are essential. In other remote sensingtechniques, due to presence of vegetation cover over an Earth’s surface, the accurate DTMderivation may be a difficult process. Similarly estimation of biomass will also be not very accurate.Airborne laser technology, unlike radar or satellite imaging, can simultaneously map the groundbeneath and tree canopy as well as the tree heights by multiple returns. Post-processing of thedata allows the individual laser returns to be analyzed and classified as vegetation or groundreturns, allowing for both ground DTM and tree canopy model such as; tree heights, crown coverand biomass. This is highly helpful in comparatively more accurate estimation of biomass.

Key words: Remote sensing, LiDAR, DTM, Bio-mass model, Degradation, Soil erosion andSustainable management.

INTRODUCTION

A LiDAR (Light Detection And Ranging)system combines a single narrow-beamlaser with a receiver system in a remoteplatform. LiDAR is typically defined as theintegration of three technologies into asingle system, capable of acquiring data.These technologies are; Lasers, the GlobalPositioning System (GPS) and InertialNavigation Systems (INS). The laserproduces an optical pulse which operatesin the infrared region of the spectrum withwavelengths from around 1064nm up to1540 nm. This is transmitted, reflected offan object, and returned to the receiver. Thereceiver accurately measures the travel timeof the pulse from its start to its return. With

the pulse traveling at the speed of light, thereceiver senses the return pulse before thenext pulse is sent out. Since the speed oflight is known, the travel time can beconverted to a range measurement.Combining the laser range, laser scansangle, laser position from GPS, highaccuracy differential GPS and laserorientation from INS, accurate x, y, z groundcoordinates can be calculated for each laserpulse. Each pulse covers a finite areadetermined by the instantaneous field of view(IFOV) of the scanner. The returned pulse istherefore a combination of the elevationswithin the field of view. LiDAR systems mayalso record “multiple returns” from the same

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pulse. The laser beam may hit leaves at thetop of tree canopy, while part of the beamtravels further and may hit more leaves orbranches and then likely to hit the groundand be reflected back, ending up with a setof recorded “multiple returns” each havingan x, y, z position. This feature can beadvantageous when the application callsfor elevations for not only the ground, but fortree or building heights. This system maybe broadly divided as Airborne LiDAR andTerrestrial LiDAR. Both techniques candeliver high resolution digital terrain models(DTM) or digital surface models (DSM) buton different scales.

Whereas resolution and accuracy forAirborne LiDAR are currently in the sub-metre range, respective values for terrestrialLiDAR are at centimetre scale.

OBJECTIVES

This paper aims at providing the relativeadvantages of LiDAR applications overconventional remote sensing methods withrespect to land degradation managementand discusses the prospects of thistechnology.

MATERIALS AND METHODS

Worldwide, LiDAR is a maturing remotesensing system, but in India it is still in theincipient stage (Behera and Roy, 2002).LiDAR data for specif ic areas is notavailable in India. Due to this lack of LiDARdata availability, a case study of applicationcould not be made in this paper. Tounderstand the parameters and postprocessing products of LiDAR system, asample data has been utilized. The maingoal of this paper is a comparison ofresearch methodology, adopted for twosets of data processing techniques. BothLiDAR data and Tele Atlas-Ortho data arecaptured for the same area at the sameperiod (Aug, 2008) and they are comparedin terms of their relative advantages forSustainable Land Management (SLM) – ori ts converse, land degradat ionmanagement.

LAND DEGRADATION

Land degradation refers to a decline in theoverall quality of soil, water or vegetationcondition commonly caused by humanactivities. The Vegetation Management Act1999 states that the phrase includes soilerosion, rising water tables, expression ofsalinity, mass movement by gravity of soilor rock, stream bank instability and aprocess that results in declining waterquality. Degradation is also considered toinclude a change in the ground cover to lesspalatable species, or a change frompredominantly perennial grasses topredominantly annual grasses (RIOConvention). It is estimated that up to 40%of the world’s agricultural land is seriouslydegraded (W ikipedia). The latestdeforestation rates are estimated around13 million hectares per year: a net loss ofabout 7.3 million hectares per year for 2000-2005 (FAO, 2005). The situation varies fromcountry to country with the type of physicalenvironment and the type of usage. Thereare sufficient studies and reviews thatclearly demonstrate the fact that landdegradation affects all facets of life. Landdegradation adversely affects agriculturalproductivity, the health of humans as wellas of livestock, and economic activities.Degradation and the associated loss ofvegetation, causes biodiversity loss andcontributes to climate change throughreducing carbon sequestration.

Figure 1A: DTM data derived from LiDAR systemsand 1B shows the same area with ortho photos in 3Dperspective view

Figure 2A: DTM data derived from LiDAR systemswith 1m interval and 2B shows DTM data with 10minterval which derived from photometric technique(Denise et al., 2006)

Figure 3: depicts the LiDAR data whereas greenpulses indicate the vegetation, red pulses forbuilding, orange pulses for ground and whitepulses represent unclassified classes

Figure 4: depicts the measuring of individual treeheights and tree cover area by using automatedvector data from LiDAR data

Figure 5A depicts Digital Surface Model and 5B DigitalTerrain Model

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Figure 3

Figure 2A Figure 2B

Figure 4

Figure 1A Figure 1B

Figure 5B

Figure 5A

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Land Degradation Management

Global assessment of land degradation isnot an easy task, and a wide range ofmethods is used. Land degradationmanagement involved three steps ofprocess addressing the problems:assessment, monitoring, and applicationof mitigating technologies. Designingappropriate strategies and approaches tomitigate the causes and impacts of landdegradation is essential. However, suitabletechnology to analyze the factors and theirinteractive effects are more important. Itshould be noted that most of the availabledata on land in conventional remote sensingshow only two dimensional parameters ofx and y and an additional z dimension helpsbetter planning.LiDAR is one suchtechnology which has the unique advantageof providing three-dimensional data withunprecedented accuracy for assessing andmonitoring land degradation. Thistechnique could be utilized to addressvarious aspects of land degradationmanagement, not possible earlier with thedata available from aerial photographs,optical and radar satellites or even byground measurements.

RESULTS AND DISCUSSION

Scientifically, the main attributor to landdegradation is soil erosion and vegetationcover changes. To analyze the soil erosionand vegetation cover changes, respectivelyaccurate Digital Terrain Model (DTM) andBio mass models are needed. LiDARprovides a comprehensive solution for boththe models in any area regardless of theenvironment or terrain. It is offering anumber of irrefutable advantages overconventional methodologies such asground survey and aerial photogrammetryincluding:

o Superior data accuracy: Collection ofthousands of pulse points per second,equating to a measurement every15cms, virtually el iminatesinterpolation and preserves surfaceintegrity.

o Penetration of tree canopy and densevegetation: Airborne Lasers penetratetree canopy even in heavily woodedenvironments. This generates anextremely accurate data set.

o Flexibility: LiDAR data can be collectedday or night and year round providingvaluable flexibility.

o Rapid turn around: Approximately 75%of LiDAR processing is automated. SoProcessed data will be delivered withinshort period from the day of acquisition.

o Verification advantage: Unlike otherremote sensing techniques, need forground control points for rectification isnot necessary in LiDAR because eachpulse has x, y and z coordinates.

o Advanced product: Many products canbe derived from LiDAR data including3D models and visualizations,Measures power l ines above thevegetation and Dynamic InteractiveVideos.

o Savings: LiDAR offers a cost effectivealternative, which saves significantamounts of time and money.

DTM Modeling

One of the primary uses of DTM is to analyzethe interaction between topographicsurface characteristics like soil erosion,relief, morphology, slope, and orientation.DTM data presents a promising way foridentification, mapping and interpretation ofsoil erosion. By comparing the temporalDTM data, it’s enough to evaluate the soilerosion and their intensity as well as spatialpattern. Remote sensing technology offerwide variety of DTM data set, both spatialand temporal manner. Although to create aperfect soil erosion model, accurate DTMdata is necessary. The high resolution DTMprovides a sound basis for land degradationmonitoring, mapping, process modellingand subsequently for hazardassessments.The accuracy of DTM data,which derived from remote sensingtechnology mainly determined by vegetationcover over an area because vegetation coverhindrance the bare earth capturing. Airbornelaser technology, unlike radar or satellite

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imaging, can simultaneously map theground beneath the tree canopy as well asthe tree heights. Post-process­ing of thedata allows the individual laser returns tobe analyzed and classified as vegetation orground returns, allows working over highresolution DTM (Figure 1A) and offers apotential alternative to field surveying,photogrammetric and other conventionalremote sensing techniques for thecollection of elevation data. Conventionaltechnologies may provide a comparativelylower accuracy of DTM due to impedimentof vegetation cover over an area. Figures 3and 4 represent the DTMs derived fromLiDAR system and photogrammetricmethod respectively. Here the accuracy maydiffer from one to the other. LiDAR providesan accuracy of one meter in DTM intervaland reflects even first order streams withclear cut slope. In contrast the conventionalmethods generally provide ten metresinterval of DTM and show only thegeneralized slope.

Tree height and bio-mass modeling

In most cases, while field and photo-grammetric methods fail to determine treeand other plant heights (Figure 1B), theycould be accurately detected by using LiDARsystem, where the ground is not visible(Figure 1A). Typical remote sensing imagesallow analyzing of various attributes offorests, but are limited in their ability torepresent spatial patterns in threedimensional space. The advantage of usingLiDAR remote sensing for forestryapplications is that it provides data on threedimensional (3D) forest structurescharacterizing vegetation heights, verticaldistribution of canopy materials, crownvolume, sub canopy topography, biomass,vertical foliage diversity & multiple layers,height to live crown, large tree density, leafarea index, physiographic or life formdiversity etc. (Behera and Roy, 2006) (Figure3 and 4).

The prediction of forest parameters is eitherdirect or indirect. For direct measurements,a characteristic such as height is estimated

by first minus last return of the raw dataalone or by applying a linear transformationto the raw data (Figure 5A and B). Indirectestimates are most often based on firstestimating a fundamental parameter suchas height which is then fed into a predictivemodel for biomass and volume.

It is amply clear that LiDAR technique hasbecome a very prominent tool to collectaccurate high-resolution three-dimensionaldata provides unprecedented accuracy forassess and monitor land degradation.

CONCLUSION

A wide variety of technologies are used forassessing the status of land degradationand its management. Though there hasbeen an increased incidence of the use ofremote sensing technology, for this LiDARseems to be a better choice due to it costeffectiveness. The technology could beutilized to address various aspects of landdegradation management, not possiblepreviously with the data available from aerialphotographs, optical and radar satellites oreven by ground measurements. One of theinherent features of LiDAR data is that it isacquired, processed, and delivered in adigital format. This makes it very easy towork with LiDAR.

The ability of LiDAR to penetrate densevegetation allows collection of data overlarge surface areas that would be difficult tosurvey in any other way and this offersdetailed elevation information acquired overlarge areas and at a higher resolution thanconventional DTMs with cost reductionmanner. The interpreted data layers areeasy to integrate with other data sources ina GIS and also efficiently incorporate innatural environments to create methodsand models for Land degradationmanagement. This technology has thepotential of conserving the precious naturalresources and providing betterunderstanding of management, which aredifficult to comprehend otherwise, due tothe limitations imposed by conventionaland other data collection techniques. In

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spite of its advantages, LiDAR does requirespecialized skilled persons and softwarefor processing and analyzing the LiDARdata sets. Another shortcoming of thetechnology is that the LiDAR data does notbring into being easy visualization like orthophotos or satellite images. Under suchcircumstances the combination of LiDARdata and satellite remote sensing data couldalso be very useful for describing andmonitoring changes in land use andbiodiversity. In addition, the typicalcharacteristics of LiDAR data have openedup the possibility of using them for manyother applications, which were not thoughtof earlier.

ACKNOWLEDGEMENTS

The authors are thankful to the UGC – UPEproject scheme, School of Earth andAtmospheric Sciences, Madurai KamarajUniversity, for providing the lab support todo this present piece of research work.

REFERENCES

Baltsavias, E.P., 1999. Airborne laserscanning: Existing systems and firmsand other resources: ISPRS Journalo f P h o t o g r a m m e t r y a n d R e m o t eSens ing.

Behera, M. D. and Roy, P.S., 2002. Lidarremote sensing for forestry applications:The Indian context. Cur. Sci., Vol. 83 (1).

Denise Laes, 2006. Lidar Applications forForestry and Geosciences. Forest ServiceRemote Sensing Applications CenterSaltLake City, UT.

Guenther, G.C., 2007. Digital ElevationModel Technologies and Applications: TheDEM Users Manual, 2nd Edition, D. Maune,ed., American Society for Photogrammetry

and Remote Sensing, Chapter 8: Airbornelidar bathymetry, 253-320.

Jensen, J., 2000. Remote Sensing of theEnvironment: An Earth ResourcePerspective. Prentice Hall: Saddle River, N.J.

Joint Liaison Group of the Rio Conventionsarticle, 2008. Forests: Climate change,Biodiversity and Land degradation.

Lillesand, T. and Kiefer, R., 2000. RemoteSensing and Image Interpretation. 4thEdition. John Wiley & Sons,

Othman Sharakas, Article: LandDegradation Risk assessment in thePalestinian central mountains utilizingRemote Sensing and GIS techniques.Department of Geography, Birzeit University.

Ambercore Website: http://www.ambercore.com

Environsciences Website : http://www.environsciences.com/ARTICLES/Lidar

USDA Website: http://soils.usda.gov/use/wor ldso i ls /papers/ land-degradat ion-overview.html

Lambda photometrics Website: http://www.lambdaphoto.co.uk/applicat ions/100.210

Optech WebSite: www.optech.on.ca

JALBTCX Website: http://shoals.sam.usace.army.mil/Publications.aspx

Terra scan and Terra model User manual:h t tp : / /www.terrasol id . f i /en/produc ts /terrascan

Wikipedia Website: http://en.wikipedia.org/wiki/LIDAR.

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STUDIES ON THE VEGETATION OF THE DELTAS OF CHANDRAGIRI RIVER,KASARAGOD DISTRICT OF KERALA

Subrahmanya Prasad, K. and Raveendran, K.

Department of Post Graduate Studies & Research in BotanySir Syed College, Taliparamba, Kannur, Kerala.

Corresponding author:prasadks.1090@rediffmail.com

ABSTRACT

A brief inventory on the vegetation of the deltas (braids) of Chandragiri river has been worked out.The vegetation is of moist mixed deciduous type. The floristic composition of the deltas vary fromthe rest of Kasaragod as they harbour a number of plants which are unique to Western Ghats. Acheck list of the identified plants were worked out. This comprises of 307 species of plantsbelonging to 242 genera and 89 families. There are 29 plants which are endemic to Western Ghatsand 3 are critically endangered.Key Words: Deltas, Chandragiri river, Western Ghats, Endemics, Critically endangered.

INTRODUCTION

Kasaragod is the northern-most district ofKerala, located between 11 0181 and120481N latitudes and 740521 and 750261 Elongitudes. Topographically it consists of acoastal belt, an undulating midland and amountainous high range. River Chandragiriis the longest among the 12 rivers ofKasaragod. The river, 105 km long,originates from Pattimala in Coorg andembraces the sea at Thalangara. The riverassumes its name Chandragiri from theplace of its source Chandragupta vasti,where the great Maurya EmperorChandragupta is believed to have spent hislast days. Characteristic feature of this riveris the presence of six deltas or braids,formed by deposition. Of these, 5 deltashave a history of several hundred years,while the sixth one is still in the formationstage, with a history of only 25 years. Theflora of these deltas vary from the flora ofrest of the Kasaragod as these have anumber of rare and endangered plants,

which are sown there by the flood water fromthe ghats. Out of these 6 deltas one iscolonized by about 110 families while inanother one, the Municipality has donemassive planting of Acacia auriculiformis(L.) Willd. saplings. Due to anthropogenicactivities the natural flora of these two deltasare almost lost and now dominated bycultivated plants. The fate of other deltasalso would be the same and hence thepresent study has been undertaken toinvestigate the floristic composition of thesedeltas, before they get vanished.

STUDY AREA

The area of present study, called ‘thurths’are with an elevation of 3-5 meters aboveMSL. Topographically the entire area is moreor less plain. During monsoon, this areahardly remains over the water, which makesit a herbal treasure with some rare plantssown by the flood water. The soil is highlyfertile Alluvium. The climate is warm humid

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* Endemic, + Critically endangered

tropical type with very little variation intemperature. The District receives anaverage rainfall of 358 cm, annually.Relative humidity varies from 70 - 90%.

METHODOLOGY

Periodic visit to the deltas were madebetween January 2008 to August 2009. Theplant specimens were collected, identifiedand classified following the regional floras(Hooker, 1892 – 1897; Gamble & Fischer,1915-1936; Manilal and Sivarajan, 1982;Ramachandran and Nair, 1988;Gopalakrishna Bhat, 2003; Anilkumar, et.al.,2005). The herbarium sheets wereprepared and deposited in the Herbariumof the Botany Department, Sir Syed College,Taliparamba.

VEGETATION

The vegetation is of moist mixed deciduoustype. The trees constituting the top storeyare Vateria indica L., Bombax ceiba L.,Pterygota alata (Roxb.)R.Br., Alianthustriphysa (Dennst.) Alston, Grewia tiliifolia

Vahl., Holigarnaarnottiana Hook.f.,Mangifera indica L.,Albizia odoratissima(L.f.) Benth.,L a g e r s t r o e m i aspeciosa (L.) Pers.,Macaranga peltata(Roxb.) Muell. Arg.,Trewia polycarpaBenth., Artocarpusgomezianus Wall exTrec., A. hirsutus Lam.etc.

The l ianas andclimbers include Uvarianarum (Dunal) Wall.,Anamirta cocculus (L.)W ight and Arn.,Diploclisia glaucescens(Bl.) Diels., Tinosporasinensis (Willd) Hook.f.and Thomas., Grewiaumbelli fera Bedd.,

Acroceras munroanum (Balansa) Henr.Alloteropsis cimicina (L.) Stapf.Apluda mutica L.*Arundinella metzii Hochst ex. Miq.Axonopus compressus (Swartz) P.Beauv.Bambusa arundinacea (Retz.) Roxb.Bambusa vulgaris Schrad.Brachiaria miliiformis (Presl.) A.ChaseCentotheca lappacea (L). DesvauxCynodon dactylon (L.) Pers.Cyrtococcum oxyphyllum (Steud.) Stapf.Cyrtococcum patens (L.) A. Camus.Dendrocalamus strictus L.Digitaria bicornis (Lamk.) Roem. & Schult.Digitaria setigera Roth. ex Roem. & Schult.Eleusine indica (L.) Gaertn.Ischaemum indicum (Hoult.) MerrillLeersia hexandra Sw.Oplismenus compositus (L.) P.Beauv.Ottochloa nodosa (Kunth.) DandyPaspalum conjugatum Berg.Pennisetum polystachyon (L.) Schult.Setaria mutica P.Beauv.

Poaceae

Stenotaphrum dimidiatum (L.) Brongn.

Ampelocissus latifolia (Roxb.) Planch.,Salacia fruticosa L., Derris trifoliata Lour.,Spatholobus parvif lorus Roxb.ex.Dc.,Entada rheedei Spreng., Calycopterisf lor ibunda Lam. , Tr ichosan thestricuspidata Lam., Zanonia indica L.,Wat takaka vo lub i l i s (L . f . ) Stapf . ,Ipomoea aculeata Blume., I.macranthaRoem. and Schult., Merremia vit ifol ia(Burm.f.) Hall.f.

Fern, fern allies and Gymnosperms are lessin the study area. The fern and fern alliesinclude Selaginella delicatala (Desv.exPoir.) Alston., Lygodium flexuosum (L.) Sw.,Pteris pellucida Presl., Adiantum lanulatumBurm.f. and Drynaria quercifolia (L.) J.sm.while Gymnosperms are represented onlyby Gnetum ula Brongn.

ENUMERATION

In the enumeration, Angiospermic familiesare arranged as in the Flora of Presidencyof Madras (Gamble and Fischer, 1915 –1936) and within families, genera andspecies are arranged alphabetically.

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RESULTS AND DISCUSSION

During this study, a total of 307 plantspecies belonging to 242 genera and 89famil ies were documented. Theangiosperms dominated with 301members, of which 243 are dicots and 58monocots. Poaceae, Euphorbiaceae andAcanthaceae are the dominant families with24, 19 and 15 species respectively. 229plants are found wild in nature while 78 arecultivated. The characteristic feature ofthese deltas is the presence of 29 plants,which are endemic to Western ghats andneighbouring areas. Garcinia indica(Dupetit-Thouars) Choisy., Ochreinaucleamissionis (W ight & Arn.) Ridsd.andArtocarpus hirsutus Lam. are the criticallyendangered species documented from thestudy area.

From detailed analysis, it is clear that thesedeltas harbour plants like Vateria indica L.,Pterygota alata (Roxb.) R. Br., Salaciafruticosa Heyne ex Lawson, Ixora brachiataRoxb., Strobilanthes membranacea Neesin Wall., Cinnamomum malabatrum(Burm.f.) Blume, Pandanus unipapillatusDennst. species which are usually found indeep forests of Western Ghats. These aretreasure house of large number ofeconomically important plants, such asCalophyllum inophyllum L., Vateria indicaL., Salacia chinensis L., Mucuna pruriens(L.) DC., Morinda citrifolia L., Plumbagozeylanica L., Gmelina arborea L.,

Aristolochia indica L., Santalum album L.,Artocarpus hirsutus Lam. and Curcumacaesia Roxb. These flora are conservedhere due to shallow water barrier andrestricted entry.

ACKNOWLEDGEMENTS

The authors are grateful to the principal andmanagement, Sir Syed College,Taliparamba for providing the facilities. Oneof the author, SPK is thankful to KSCSTE forfinancial support.

REFERENCES

Anil Kumar, N., Sivadasan, M., & Ravi, N.,2005. Flora of Pathanamthitta, DayaPublishing House, Delhi.

Gamble, J.S. and Fischer, C.E.C., 1915 -1936. Flora of the Presidency of Madras,Adlard and Sons Ltd., London.

Gopalakrishna Bhat, K., 2003. Flora ofUdupi, Indian Naturalist (R), Udupi.

Hooker, J.D., 1892 - 1897. The Flora ofBritish India, Reeve and Co., London.

Manilal, K. S. and Sivarajan, V.V., 1982. Floraof Calicut, Bishen Singh Mahendra PalSingh, Dehra Dun.

Ramachandran, V. S., and Nair, V .J., 1988.Flora of Cannanore, BSI Calcutta.

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ASSUMPTIONS ON SURVIVAL STRATEGIES OF MARINE FUNGI IN OCEANS

Venkateswara Sarma, V.

Department of Biotechnology, Pondicherry Central University, Pondicherry

Corresponding author: sarmavv@yahoo.com

ABSTRACT

In marine environments, availability of woody substrata is scarce, on which marine fungi grow andthrive. Under stress conditions it is surmised and hypothesized that the marine fungi could resort tomicrocycle conidiation, which has been reported for terrestrial fungi belonging to the anamorphicstates of a few ascomycetes. Probable methods of detection of microcycle conidiation have alsobeen discussed.

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INTRODUCTION

There are more than 440 species of typicalmarine fungi that have been reportedrecently (Hyde et al., 2000). Although severalworkers have proposed different definitionsfor marine fungi, the most widely accepteddefinition has been that of Kohlmeyer andKohlmeyer (1979), namely, “obligate marinefungi are those that grow and sporulateexclusively in a marine or estuarine habitat;facultative marine fungi are those from afreshwater or terrestrial mileu, able to growand possibly also sporulate in the marineenvironment.” Marine fungi occur ondifferent substrata including driftwood,mangrove wood, roots, pneumatophores,prop roots, seedlings, on algae, calcareousshells, salt marshes, dead corals, sandgrains, etc. Their presence has been moreprominent in the coastal ecosystems andalmost negligible in pelagic waters(Raghukumar, 1988).

The propagules of filamentous marine fungiviz. spores/conidia attach to wooden crafts,ships, drift wood or any other plant/animalsubstrata, form mycelia and expand through

vegetative growth and under unfavourableconditions, once again form reproductivestructures i.e. spores/conidia in the marineenvironments (Kohlmeyer and Kohlmeyer,1979). Since the avai labi l i ty of thesubstratum not only acts as a nutrientsource but also as an anchoringsubstance, i t is generally fel t thatfilamentous marine fungi play a minor rolein pelagic waters of open seas indegradation processes, leaving bacteria,thraustochytrids and yeasts to play a majorrole in detritus cycle (Raghukumar, 1988).It is understandable that filamentous fungiwhich require a larger substratum to formmycelium cannot grow and multiply insmaller substrata, which are available inthe pelagic waters. On the contrary it hasbeen proved that fungi play more importantroles than bacteria in nutrient recycling anddegradat ion processes in coastalecosystems including mangroves,estuaries (Fell and Master, 1980). This isbecause large amounts of woody substrataare available in the coastal ecosystems,unlike the open seas.

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SURVIVAL OF MARINE FUNGI

The reproductive propagules of fungi suchas spores/conidia like any other groups oforganisms are survival propagules and cantide over many unfavourable conditions untila chance occurrence of a substratum whichmight trigger the germination of theseregular reproductive propagules. If such achance occurrence of a substratum is bigenough then fungal colonization will takeplace and until such time any stress iscaused the fungus wil l remain in thevegetative stage. On the other hand if thesubstratum is very small and if the marinefungal spores/conidia adhere to such verytiny substrata then a question arises as towhether these regular fungal propagulesgerminate at all? Even if they germinatewould the nutrients available and the girth/surface/length/width/ of the tiny substratumbe conducive for fungal hyphal growth andin turn mycelium formation? Under suchcircumstances would the marine fungi,instead of again producing the regularpropagules, switch over to a mode entirelydifferent, which would suit the size andvolume of nutrients available in thesubstratum? That means such fungi wouldnot be able to form their usual fungalpropagules and instead have to adoptdifferent strategies. There are certainunusual strategies adopted by fungiincluding microcycle conidiation (asexual)and spermatia formation (sexual) which arewidely reported in the literature (Ahearn etal., 2007; Bacon and Hinton, 1991; Grangeand Turian, 2004; Antipova et al., 2005;Khurana et al., 1993; Maheswari, 1991;1999; and Saxena et al., 1992).

MICROCYCLE CONIDIATION ANDASSUMPTIONS ON SURVIVAL STRATEGIESOF MARINE FUNGI

Microcycle conidiation i.e. directconidiogenesis from a conidium or sporewith minimal intervening hyphaldevelopment, for several decades has beenconsidered a survival mechanism duringstress for a variety of moulds (Ahearn et al.,

2007). In microcyclic conidiation, immediateconidiation occurs, fol lowing conidialgermination without an intervening phaseof prolonged vegetative mycelium.Microconidiation is reported to occur undernutrient-limiting conditions (Saxena et al.,1992) and might help the fungi to completetheir l i fe cycles in a shorter t ime(Raghukumar and Raghukumar, 1998).Though these unusual structures of fungiare well known phenomena in terrestrialenvironments, the frequency of fungi shiftingto such a mode in nature could be rare.Unfortunately we don’t have muchinformation on this aspect in nature. In thecontext of open seas, in the planktonic regionwhere only tiny susbstrata that have loweramounts of nutrients (in the organismbiomass) are available, would filamentousfungi (marine or otherwise?) resort to theproduction of microcycle conidiation orspermatia formation, not only as one of thesurvival strategies but also as a routinemethod of multiplication, to degrade thesubstrata available in the open seas suchas dead and decaying planktonic members(microplankton, mesoplankton andmacroplankton)? Whenever favourableconditions come they could switch over tothe regular reproductive structures(propagules) of filamentous fungi. It issurmised and hypothesized here thatfilamentous marine fungi would routinelyresort to the mode of microcycle conidiationand spermatia formation as a routinemethod of survival and multiplication inpelagic waters. Further discussion in thispaper is based on the above assumption.

The existing knowledge would actuallycounter the above assumption in that mostof the marine filamentous fungi are knownto be lignicolous and hence require largerwoody substrata for growth andmultiplication (Kohlmeyer and Kohlmeyer,1979). And most probably they are adaptedfor such a mode where they can colonizemostly the woody substrata. More than halfof the typical marine fungi are found only ondriftwood and such fungi do not occur onother substrata of the coastal ecosystems

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e.g. dead and decomposing mangrovewood, shoreline plants, salt marshes, etc.But again the question comes how doesmarine fungi survive in the marineenvironments that too when the substratumavailability is a chance occurrence? Howmany drift wood pieces are found in the vastoceans at any given point of time for longterm survival of marine fungi? We know thatthe spores/conidia are survival propagulesand there are cases in terrestrialenvironments where such spores canremain viable even for more than 100 yearsuntil favourable conditions come. If thatwere the case then all the marine fungalpropagules could also remain in dormantform, drifting in the sea waters, for severalmonths or even years until the day when adriftwood comes in contact. If the latter istrue then the role of marine fungi in openseas, in terms of degradation processesor any other involvement is completelynegligible as speculated by Raghukumar(1988). But instead of completelydismissing the role of fungi in open seas,could we think of any other strategies thatare adapted by the filamentous fungi?Hence there is a necessity to study from adifferent angle and see whetherfilamentous marine fungi have any otherstrategies of survival and special mode oflife before attaining their usual structures ofpropagules when favourable conditionsoccur. It is against these questions theassumption that there could be a possibilitythat the filamentous marine fungi formmicroconidia or spermatia as survival andmultiplication strategies has arisen. It wouldremain as a far fetching idea if thehypothesis is not proved experimentally. Toprove the above assumption the followingmethods and approaches are suggested:

(i) Culture marine fungi and routinely checkfor the presence of microcycle conidiationand/or spermatia formation in the artificialculture media. Studies could also beconducted to check whether providingdifferent types of stress could inducemicrocycle conidiation. In the case ofterrestrial fungi it has been proved that

microcycle conidiation could be induced byproviding a stress either through change inthe nutrient formulation or other abioticstress (Antipova et al., 2005; Khurana et al.,1993; Maheswari, 1991; Saxena et al.,1992).

(ii) Around 80% of marine fungi belong toascomycetes, having small fruit bodiesoccurring on decomposing natural plantsubstrata (Hyde et al., 2000; Sarma andVittal., 2000). Hence whenever we observethe natural substrata for marine fungi weshould also look for microconidia orspermatia (in tiny fruit bodies) that mightoccur along with the regular propagules.

(iii) Make attempts to observe the micro,meso and macroplanktonic members,preferably the dead ones, for the presenceof unusual structures such as microcycliccondia/spermatia as well as regular fungalpropagules. This needs collection of opensea (pelagic) water samples (10 – 30 L)which need to be centrifuged or filtered toconcentrate the organisms and thenobserve under microscope. Here again theepiflourescence microscopy (EPM) wouldbe the best technique to check for thepresence of fungal hyphae and manystudies have fol lowed this technique(Raghukumar and Raghukumar, 1998;Mueller and Sengbusch, 1983;Raghukumar and Schaumann, 1993;Damere and Raghukumar, 2007; Damereet al,. 2006). EPM is also helpful inimplicating the functional roles offilamentous fungi in ecological processes.

(iv) Last but not the least moleculartechniques might throw some light on theactive roles of marine fungi. After filtering orcentrifuging enough open sea watersamples the DNA could be extracted to runPCR with universal fungal primers foramplifying 18sRNA segments and thensequencing the amplicons would show thepresence or absence of filamentous fungi.In this process there might be severalterrestrial fungi that would have shownsignatures in the molecular analysis. This

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could be due to the presence of spores ofterrestrial fungi, which would have come toopen seas as runoff, and hence aretransients but not native marine mycoflora.The best way is to collect the planktonicbiomass and process for filamentous fungi.Even in this case also, there are chances ofterrestrial fungi propping up in the DNAextractions. Nevertheless the marine fungiwould also show off if their numbers werelarge enough. If we find marine fungalsignatures from open seawater samples,then the question arises as to whether thesemarine fungi have propped up from theirroutine propagules or from any unusualpropagule structures discussed above.

Recent studies have shown the presenceof hyphae of filamentous fungi under deepsea conditions (Raghukumar andRaghukumar, 1998; Damere andRaghukumar, 2007; Damere et al., 2006).We have information on deep-sea fungirecorded and growing at higher pressures(Raghukumar and Raghukumar, 1998).Unusual conidial structures of filamentousfungi when grown in artificial media undersimulated high pressure (deep-sea)conditions were reported by Raghukumarand Raghukumar (1998). The authors havesuspected that such unusual conidialstructures could be akin to microcycleconidiation (Raghukumar andRaghukumar, 1998). Except the abovereference, where only a passing remark ismade, there is no report available, As far asauthor’s knowledge goes, in support of themain argument of the presentcommunication that is suggestive ofmicrocycle conidiation as one of the survivalstrategies of marine fungi.

Normally spermatia and microconidia havedon’t offer much structural diversity orcomplexity and mostly they look alike. Thisproblem would compound if any of themhave to be identified microscopically. Henceto identify the species exactly the only wayseems to resort to 18sRNA sequencing.

The structures of thraustochytrids andyeasts, by virtue of their simplicity, are moresuited for their life in pelagic waters todegrade even smallest food particles in thedetritus cycle. The typical marine fungi(filamentous fungi) turning into microcycleconidiation would be duplication of thestructures of thraustochytrids and yeasts fora competitive role. However what is puzzlingis how the filamentous marine fungi survivein such a large oceanic system if notresorting to other modes of reproductionand multiplication?

As a parallel to the above hypothesis i.e.f i lamentous marine fungi routinelyproducing microconidia and/or spermatiain oceanic waters, we can also discuss thephenomena of microcyclic conidiationadopted by species of Aspergillus andPenici l l ium in terrestrial soils. In theterrestrial environments we find lot of litterfalling on the floor and getting degraded atvarying pace. While the intact fallen deadleaves or twigs are degraded by typical litterfungi, their diversity is not seen once thelitter reaches the friable stage andpowdered by the action of fungi and bacteria,burrowing animals, solar radiation orphysical abrasions. In the soil, once the litteris completely powdered it becomes a partof humus or organic content of the soils.While the init ial saprophytic fungalcolonizers are almost always thedematiaceous hyphomycetes towards theend of the degradation and that too in thesoi, probably, the moniliaceous fungi suchas aspergilli/pennicilli degrade the finalstage of the litter. We all know that wheneverwe collect the soil samples and plate them,after serial dilutions, we invariably end upin getting aspergilli/penicilli. Interestinglyeven in those soils that have feeble organiccontent also we get similar results. Wouldaspergil l i/penici l l i occupy the climaxcommunities degrading whatever t inypieces of litter that is left over on the floorafter degradation by typical litter degradingfungi and other actions as mentionedabove? If that is the case then do these fungi

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have enough areas to germinate, colonize,expand and establish mycelia? If not, interrestrial soils, would it be the case thatthe tiny pieces of organic content are furtherdegraded by aspergilli/penicilli resorting tothe mode of microcyclic conidiation? Thenwhenever we plate soil samples weinvariably get colonies dominated by thespecies of Aspergillus and Penicillum. Havethey come from regular conidia or frommicrocyclic conidia? Do we have anyinformation on this? When we analyzethrough molecular techniques we would getthe sequences showing similarity to aparticular species but we may not knowwhether the fungus is in the microcyclicconidial stage or the regular (usual) conidialstage. We need to direct our future studieson this aspect to properly understand thestrategies adopted by filamentous fungiunder space and nutrient limiting conditionsin natural conditions also.

REFERENCES

Ahearn, D.G., Price, D., Simmons, R.B.,Mayo, A., Zhang, S.T. and Crow, S.A. 2007.Microcycle conidiation and medusa headconidiophores of aspergil li on indoorconstruction materials and air filters fromhospitals, Mycologia 99: 1-6.

Antipova, T.V., Zhalifonova, V.P., Kockina,G.A. and Kozrovski, A.G. 2005. Growth andbiosynthesis of Rugulovasins in Penicilliumvariable Sopp 1912. Microbiology 77: 446-450.

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