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ISSN 0097-8078, Water Resources, 2009, Vol. 36, No. 6, pp. 625–631. © Pleiades Publishing, Ltd., 2009.
625
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Human population continues to grow. The demandplaced on the groundwater resources is ever increasing.As an around 80% of the people of India rely ongroundwater as their source of water supply. The insuf-ficient recharge and unscrupulous withdrawal hasinduced declining trend in the water table of the coun-try. For instance, the water table is reported to havefallen by over 10 meters in some localities in Delhi andin some other places such as Chennai and Chandigarh,it is reported they have fallen over 20 meters [56]. Thesituation is almost same in other parts of the country.The increasing demand has created a need to defineaccurately the spatial distribution of recharge acrosslarge areas. Understanding the recharge component andthen its quantification is a prerequisite for effectivewater budgeting, liquid, solid and nuclear waste dis-posal. It has been suggested that the “dead cell” or“stagnation points” might be appropriate areas in whichto inject waste fluid for permanent disposal [33].
The water moves through the porous media underthe influence of fluid potential [12]. Recharge, can bedefined as the water that crosses the vadose zone to jointhe water table. Before crossing the vadose zone andjoining the water table it depends on a variety of fac-tors. Winter [61] has proposed the three main factors inthe hydrologic landscape that control water flow: cli-mate, topography, and geologic framework. This makesthe recharge component as one of the most complexand uncertain component of hydrologic cycle.
The long term safe yield for the sustainable develop-ment is not related so much to the undisturbed rechargeto the natural aquifer system, but rather to the rechargeof the disturbed system and the proportion of the dis-charge that the ground water extraction centers are ableto capture [4, 31]. The nonlinear relation interactionamong recharge—discharge boundary conditions, and
1
The article is published in the original.
changes in groundwater storage make solution to theseproblems difficult to resolve without careful accountingof the system parameters and their geographical distri-bution [48].
Hubbert’s Model
Water level is an important component in delineat-ing the recharge zones. Many workers [7, 19, 38, 43]have tried to delineate the water table often termed as“free surface”. Hubbert [22] presented the first descrip-tive model of regional steady state groundwater flow inan unconfined aquifer. In this model the relationship ofwater table, hydraulic head and equipotential lines arevery well demonstrated.
Figure 1 shows four piezometers A, B, C, and Dinstalled with bottom end open. The hydraulic head isequal in the piezometers that end at the same equipoten-tial lines, though their depth is different (A and B).However, the hydraulic head in the piezometer C and Dvaries as both ends at different equipotential lines. Thehydraulic head in the piezometer is the level whereequipotential lines cut the water table. At the piezome-ter “A” the hydraulic potential decreases with the depth.This is indicative of downward flow direction. Areaswith this distribution of potential are recharge areas fora water table aquifer. In the deep piezometer D thehydraulic head is higher than of piezometer C. Thisindicates hydraulic potential increases with depth. Thisis typical of discharge area. This model depicts that thecrest of the water table represent the groundwaterrecharge area while the valley bottom of the water tablerepresent the discharge area [12]. Thus, knowing spa-tial distribution of recharge—discharge zones is imper-ative for a scientific approach towards solving the prob-lem of unethical intervention in the natural system.
Groundwater Recharge: A Hydrogeologic Thought
1
A. K. Taqveem
Department of Geology, A.M.U.Aligarh-202002, India
Received November 5, 2007
Abstract
—The ensuing paper imparts vital information on an important component of the hydrologic cycle:recharge. Water flows through the porous media and forms a definite flow pattern that can be depicted in anelaborate manner through the micro level studies at the small watershed level. The estimation of recharge isindispensable for the groundwater budgeting studies. The advantages and disadvantages of some of the tech-niques have been reviewed. In the present paper an attempt is made to develop a fundamental understanding ofthe spatial and temporal distribution of the recharge component and to attract excellent research in the samefield.
DOI:
10.1134/S0097807809060025
WATER RESOURCES AND THE REGIME OF WATER BODIES
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Water Table and the Recharge
In a common reference it is considered that thewater table follows the topography. It was the Toth [59]who offered a regional groundwater flow solution andassumed the position of the water table as the replica ofthe topography. In many settings the water table andsurface topography seem poorly correlated or some-what unrelated [3, 8, 37, 50].
Toth [59] in his conceptual model for local, interme-diate, and regional flow pattern considered both thehorizontal and vertical components in the flow regime.This view of nested flow components is in contrast tothe Dupuit [10] and Forchhmeimer [13] approximation.These two ignored vertical component of flow in theregional scale setting and only considered the horizon-tal flow in their model.
In the modern interpretation there is no room for thenested flow cells as proposed by Toth [59] but verticalflow is allowed with no resistance [26, 55]. Toth [59]developed the conceptual model while studying thehummocky terrain of Alberta, Canada. The region isknown to contain areas of deep aquifers of low-perme-ability shales and sandstone overlain by a relatively thinlayer of higher permeability sands [39]. The model hedeveloped had a great depth and large distance betweendrainage divide and the stream.
In order to the water table to rise to the highest pointin this theoretical watershed, the ratio of recharge andhydraulic conductivity must be greater than 0.2 [36].This recharge—hydraulic conductivity ratio is quitehigh and is only possible when the low permeabilitybasin is overlain by a high permeability vadose zone, asthe case was in Toth’s study. The thick permeable
vadose zone will store more precipitation rather thanallow a high run-off and would give sustained rechargeto the aquifer.
Haitjema [16] has examined two situations (i) wherethe recharge—hydraulic conductivity ratio is relativelylow and, (ii) where the recharge—hydraulic conductiv-ity ratio is relatively high. In the first situation
R
/
k
=0.08 and the head is specified (Figs. 2a, 2b). In Fig. 2athe water table is well below the land surface, therecharge area is more. The discharge is in sink, wherethe head meet the low-lying land surface. In Fig. 2bwhere the
R
/
k
is relatively more i.e. 0.4, the water tablerises to intersect the land surface at two points, whichare the discharging points. The flow pattern is dividedinto two units. A local flow cell has developed on theleft hand side near the bottom of the watershed. On theright hand side the recharge area has shrunk due to therise in the water table. In the Fig. 2b if the water tableis measured it appears that it is the subdued replica ofthe topography. But when it is examined in the situationwhere water table is the replica of land surface (Fig. 3a)different flow system is obtained. Here numerous localflow cells are formed with zones of vertical flow.Numerous recharge and discharge cells are formed.This is the typical example that shows the heterogeneityof the aquifer system.
If the head-specified upper boundary conditions areapplied to a deeper aquifer as shown in Fig. 3b with anincrease in basin depth ratio, there develops the three-flow systems local, intermediate and regional [16]. Thisintermediate flow systems have at least one local flowsystem between the recharge and discharge areas.Regional flow systems have the recharge area in the
Recharge area Discharge area Reccharege area
C DA
B
Equipotential lines
Flow linesWater table
A, B, C & D – Piezometers
Fig. 1.
Water level in piezometers and the flow lines (Modified after Fetter [12]).
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GROUNDWATER RECHARGE: A HYDROGEOLOGIC THOUGHT 627
basin divide and the discharge area at the valley bottom[12]. The model is the same as that of Toth [59]. Thisdepicts that
R
/
k
ratio play a key role in forming the localcell units. More the
R
/
k
ratio, more the heterogeneousflow system is.
Controlling Factors
Hydrogeologist are working intensely on therecharge of groundwater, where unsaturated zone orvadose is quite thick [30, 35, 45, 57, 60]. Rechargedepends on a wide variety of factors (e.g. vegetation,
precipitation, climate, topography and soil type) mak-ing it one of the most complex and uncertain hydrologicparameter to quantify [9].
If the climate and soil condition allows recharge toreach the water table at a rate that is greater than the sat-urated zone can transmit the recharge away, then thepermeability of the geologic framework controls therecharge rate. This situation results in the condition ofshallow water table because storage of water under-ground backup to the point that excess infiltration isdiverted overland [61]. This situation is associated withrelatively low permeable or anisotropic aquifers with
Discharge zone
305 m
7620 m
Land SurfaceWater Table
Discharge zone
7620 m
305 m
(a)
(b)
Fig. 2.
Flow simulation of theoretical aquifer using recharge—specified boundary conditions, (a) recharge = 25.4 mm/year, hydrau-lic conductivity = 0.3 m/d; (b) recharge = 126 mm/year, hydraulic conductivity = 0.3 m/d (after Mitchell–Bruker [36]).
305 m
7620 m
(a)
(b)
305 m
7620 m
Fig. 3.
Flow simulation of theoretical aquifer using head—specified boundary conditions, (a) 1000 ft aquifer depth, (b) 10000 ftaquifer depth (after Mitchell-Bruker [36]).
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high rainfall and flat terrain. Consequently there will berise in the water table and mounds will form. Haitjema[16] offered a dimensionless relationship to estimatethe mound formed due to the excessive recharge.
Where,
Δ
h
[m] is the mounding or rise in water tablebetween streams,
d
[m] is the water level before themounding commenced,
L
[m] is the distance betweenthe streams/diameter in a radial flow,
R
[m/d] is therecharge rate,
m
is 8 or 16 depending on the flow prob-lem being one dimensional or radial respectively,
k
[m/d] is the hydraulic conductivity of the aquifer,
H
[m]is the average thickness of the aquifer,
k
h
is the horizon-tal hydraulic conductivity, and
k
v
is the vertical hydrau-lic conductivity.
In the climate control recharge, the saturated zonetransmits more water than the climate and the vadosezone can provide. In this situation the water table shallbe deep. In regions with relatively arid climate or hightopographic relief, the climate controls the rate ofrecharge, whereas in regions of relatively humid cli-mate or low topographic relief the geologic frameworkcontrols the rate of recharge. Variability of the topogra-phy (Fig. 4) or the geologic framework within the flowsystem causes different controls to operate in differentregions [48].
Haitjema [16] offered a dimensionless criterion toasses water table is topography controlled or rechargecontrolled
If the factor on the left hand side is more than one—the water table is controlled by the topography.
Δh/d 1RL2/mkHd L �kh/kvH≥( ).=
RL2/mkHd 1.>
On the other hand if the water table is recharge con-trolled the following dimensionless condition will holdtrue.
These two criteria are developed for Dupuit andForchheimer flow conditions where distance betweensurface waters is large compared to the aquifer thick-ness i.e. the distance between two surface water bodiesshould be five times the thickness of the aquifer.
Recharge Estimation
Recharge estimation has always fancied the waterscientist. In the estimation of the recharge componentsscale is considered an important factor. The scale ofinvestigation influences the level of parameter detailneeded to characterize the system, and the choice of anappropriate measurement technique is often evaluatedaccording to the size of the study area [49].
The community scale extends upto several Sq. kms.and regional scale should encompass an area of 100 to10000 sq kms. The scale to which recharge is definedhas varied opinions, depending on the methods used forthe purpose of quantification. Like, well hydrographanalysis [24], stream hydrograph separation [32] andgeochemical tracers [49]. The Groundwater ResourceEstimation Methodology [15] has given due consider-ation to the scale factor and suggested that instead ofadministrative boundaries, hydrogeological boundaries(watershed) be considered for the estimation ofrecharge.
Historically, hydrograph analysis techniques havebeen developed for streams and spring discharge data[40]. Relatively few studies [1, 44, 51] have been con-ducted that yield quantitative data on aquifer parame-
RL2/mkHd 1.<
Evapotranspiration
SurfaceWater
Lowland
ValleySide
Direction ofSurface–waterflow
Precipitation
Watertable
Upland
Direction ofgroundwaterflow
Geologic Framework
Fig. 4.
The dominant factors affecting recharge and groundwater flow (after Winter [61]).
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GROUNDWATER RECHARGE: A HYDROGEOLOGIC THOUGHT 629
ters using well hydrographs. One motivation for exam-ining the analysis of hydrographs for estimation of
T
and specific yield was that traditional aquifer testingmethods require pumping large quantities of waterfrom the aquifer [42]. The limitation with thehydrograph analysis method is that it is limited to a sin-gle well observation. For its expansion a strong networkof observation stations and their regular monitoring isrequired. If this is done than the accuracy of the resultwill bear more credence.
Stream hydrograph separation analysis is used toestimate recharge and discharge because dailystream—discharge measurements are the only datarequired [2, 11, 41]. This method can be used to an area,which has water divides as its boundaries. The automa-tion of hydrograph separation has made the varioustechniques easier to implement [25, 34, 46, 47, 52]. Theautomated techniques estimate the recharge rate that issimilar to manual estimates [32, 46, 47]. While an auto-mated technique enforces a more consistent approachto identify groundwater discharge than the manualequivalent, the automated technique is still highly sub-jective and affected by the same underlying assump-tions. If the basic assumptions are not met, automatedhydrograph—separation—techniques become idealtools for the preservation and spreading of hydrologicmisconceptions [17, 27]. The assumptions made in thehydrograph—separation—analysis are
there exist a direct correlation between groundwaterrecharge events and stream discharge peaks;
evapotranspiration from the saturated zone, wet-land, surface water bodies, and streams storage is neg-ligible;
bank storage is negligible;
interaction between shallow aquifer and deep aqui-fer system is negligible; hydraulic characteristics of thecontributing aquifer (recession index) can be estimated;
the period of exclusively groundwater discharge canbe estimated. Stream discharge peaks approximate themagnitude and timing of recharge events. The tech-nique has its limitations too. Some of them are baseflowfrequently is not equivalent to groundwater dischargebecause other hydrologic phenomenon can noticeablyaffect stream discharge; natural and human inducedstresses such as climate and land management do affectthe baseflow [14, 41];
it is assumed that streams have no slope and thatgroundwater discharges uniformly to all reaches,though which is otherwise;
drainage from bank storage, wetlands, surface waterbodies, and soils exceeds groundwater discharge;groundwater discharge during recession periods maybe obscured by discharge from lakes, marshes, snowand ice, and bank storage [21].
Because of the violation of the main assumptionsthe technique is characterized as inconclusive [17, 18].
Investigators wanting to use hydrograph separationtechnique to estimate groundwater discharge orrecharge should also do with caution and with carefulconsideration of the degree of deviation from the modelassumptions [17].
Groundwater models are used in water budgetingstudies. In this, the hydraulic properties and boundaryconditions are used as a major input for the estimationpurposes. Recently, watershed models have been pro-posed as means to estimate groundwater rechargeacross scales ranging from local to regional watershed[6, 54].
Hydraulic conductivity varies with factors such assoils porosity, pore size, and water temperature. Manyresearchers [20, 28, 29, 53, 58] have attempted to clar-ify the relationships of hydraulic conductivity to thesefactors. The hydraulic conductivity shows a direct rela-tion to the temperature and pore size [23].
The reliability of recharge in models depends on theaccuracy of hydraulic conductivity inputs [49]. Thus,the models with uniform hydraulic conductivity or withlimited values of the same give recharge results theaccuracy of which is not known. So, more the hydraulicconductivity inputs better are the results.
Cherkauer [6] has formulated an empirical relationbetween normalized recharge and readily available cli-matic, topographic, hydrogeologic, and land measuresfor small watershed in the glaciated terrain.
A normalized annual recharge
R
/
P
(recharge perunit precipitation in cm/cm) was correlated with themultiple regression analysis. The formula is
Where
K
v
is effective vertical soil conductivity(m/d);
S
is average hill slope in watershed (m/m);
D
w
isaverage depth to the water table (m);
L
f
is the length offlow to the main channel (drainage area/2
×
channellength) (km);
D
is the portion of developed land in thewatershed (as a %).
This formula is best suited for wet land. The equa-tion give best results with the following limits;
K
≤
2.7(m/d); Natural land cover
≤
30% average hill slope
≥
0.03; Depht to the water table
≥
9.1 m and develop-ment
≥
5% [6].
SUMMARY
Water table is an important parameter in delineatingthe recharge and discharge zones. For a pragmaticapproach in the management of the groundwaterresources a micro level study has to be carried out at thesmall watershed level. The study of groundwatershould begin with a small watershed as a unit area ofinvestigation.
The crest of the water table is the area of rechargeand the trough is the area of discharge. The recharge—
R/P 0.0085 Kv /SD0.3( ) 4.18 Dw/L f{ }–=
+ 0.0025 N{ } 0.0022.+
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hydraulic conductivity ratio is a key parameter in deci-phering the heterogeneity of the aquifer system. Thedeep water table indicates the saturated zone transmitmore water than the vadose zone can provide. The shal-low water table depicts that the vadose zone providesmore water than the saturated zone can transmit. Theresult of Recharge estimation has little credence with-out the proper consideration of the spatial and temporaldistribution of the recharge component. Different tech-niques with a comprehensive approach are necessaryfor a credible estimation of the recharge.
REFERENCES
1. Atkinson, T.C., Diffuse Flow and Conduit Flow in Lime-stone Terrain in the Mendip Hills, Somerset (Great Brit-ain),
J. Hydrology
, 1977, vol. 35, pp. 93–110.2. Bevans, H.E., Estimating Stream—Aquifer Interactions
in Coal Areas of Eastern Kansas by Using StreamflowRecords, in
Selected Papers in the Hydrologic Sciences
,Subitzky, S., Ed., USGS Water—Supply Paper, 1986,vol. 2290, pp. 51–64.
3. Blaskova, S., Beven, K., Tachecci, P., and Kulasova, A.,Testing the Distributed Water Table Predictions of TOP-MODEL (Allowing for Uncertainty in Model Calibra-tion): The Death of TOPMODEL?,
Water ResourcesRes.
, 2002, vol. 38, no. 11, pp. 1257–1268.4. Bredehoeft, J.D., Papadopulos, S.S., and Cooper, H.H.,
Jr., Groundwater: the Water—Budget Myth, in
U.S. Nat-ural Research Council Studies in Geophysics: ScientificBasis of Water Resource Management,
Washington DC:National Academy Press, 1982, pp. 51–57.
5. Cherkauer, D.D., Quantifying Ground Water Recharge atMultiple Scales Using PRMS and GIS,
Ground Water
,2004, vol. 42, no. 1, pp. 97–110.
6. Cherkauer, D.S. and Ansari, Sajjad, A., EstimatingGround Water Recharge from Topography, Hydrogeol-ogy, and Land Cover,
Ground Water
, 2005, vol. 43, no. 1,pp. 101–112.
7. Davis, S.N. and De Wiest,
Hydrogeology
, New York:Wiley, 1966.
8. Desbarats, A.J., Logan, G.E., Hinton, M.J., andSharpe, D.R., On the Kriging of Water Table ElevationUsing Collateral Information from a Digital ElevationModel,
J. Hydrogeology
, 2002, vol. 255, no. 1, pp. 25–39.
9. Dripps, W.R., Hunt, R.J., and Anderson, M.P., Estimat-ing Recharge Rates with Analytic Element Models andParameter Estimation,
Ground Water
, 2006, vol. 44,no. 1, pp. 47–55.
10. Dupuit, J., Estudes Theoriques at Practiques Sur leMouvement des Eaux dans les Canaux Decouverts at atravers les Terrains Permeables (2nd ed.), France: Paris,Dumod, 1863.
11. Faye, R.E. and Mayer, G.C., Groundwater Flow andStream-Aquifer Relations in the Northern Coastal Plainof Georgia and Adjacent Part of Alabama and SouthCarolina, WRI, USGS, 1990, pp. 88–4143.
12. Fetter, C.W., Applied Hydrogeology, Ohio: Merrill Pub-lishing Company, 1988.
13. Forchheimer, P., Uber die Ergiebig keit von Brunnen—Anlogen und Siekersehlitzen, Zeitschrift des Architecte-nund Ingenieurs Vereins Zu Hunnover, 1886, vol. 32,pp. 539–564.
14. Gebert, W.A. and Krug, W.R., Streamflwo Trends inWisconsin’s Driftless Area, Water Resources Res., 1996,vol. 32, no. 4, pp. 733–744.
15. Ground Water Resource Estimation Methodology,Ground Water Resource Estimation Committee Report,Govt. of India: Ministry of Water Resources, 1997.
16. Haitjema, H.M. and Mitchell-Bruker, Sherry, Are WaterTables a Subdued Replica of the Topography?, Ground-water, 2005, vol. 43, no. 6, pp. 781–786.
17. Halford, K.J. and Mayer, G.C., Problems Associatedwith Estimating Groundwater Discharge and Rechargefrom Stream Discharge Records, Ground Water, 2000,vol. 38, no. 3, pp. 331–342.
18. Hall, F.R., Base Flow Recession, Arcview, WaterResources Res., 1968, vol. 4, no. 5, pp. 973–983.
19. Harr, M.E., Groundwater and Seepage, New York:McGraw-Hill, 1962.
20. Hazen, A., Some Physical Properties of Sands with Spe-cial Reference to Their Use in Filtration, Ann. Rpt. Mass.State Bd. Health, 1892, p. 541.
21. Horton, R.E., Discussion of Report of Committee inYield of Drainage Areas, J. New England Water WorksAssociation, 1914, pp. 538–542.
22. Hubbort, M.K., The Theory of Groundwater Motion, J.Geology, 1940, vol. 48, no. 8, pp. 785–944.
23. Iwata, S., Tabuchi, T., and Warkentin, B.P., Soil WaterInteractions, Mechanism and Applications, USA, NewYork: Marcel Dekker Inc., 1995, pp. 270–277.
24. Ketchum, J., Donovan, J., and Avery, W., Recharge Char-acteristics of a Phreatic Aquifer as Determined by Stor-age Accumulation, Hydrogeology J., 2000, vol. 8, no. 6,pp. 579–593.
25. Kinsel, W.G., Jr. and Sheridan, J.M., Procedure for Char-acterizing Hydrologic Processes in the Coastal Plain ofthe Southeastern United States, in Proceedings Hydrol-ogy on Large Flat Lands, UNESCO International Pro-gramme on Hydrology, Argentina: Buenos Aires, 1983.
26. Kirkham, D., Explanation of Paradoxes in Dupuit-Forchheimer Seepage Theory, Water Resources Res.,1967, vol. 3, no. 2, pp. 609–622.
27. Klems, V., Dilettantism in Hydrology: Transition or Des-tiny?, Water Resources Res., 1986, vol. 22, no. 9,pp. 177S–188S.
28. Kochi, K. and Suezawa, H., On the Control of Percola-tion of Sandy Soil, J. Agric. Eng. Soc. Jpn., 1937, vol. 9,pp. 381–393.
29. Kozeny, J., Die Durchlassigkeit des Bodens, Kulturtech-niker, 1932, vol. 35, pp. 301–307.
30. Krishnamurthy, N., Sunada D.K., and Longerbaugh,R.A., Mathematical Modeling of Natural Ground WaterRecharge, Water Resources Res., 1977, vol. 13, pp. 720–724.
31. Maddock, T., III and Vionnet, L.B., Groundwater Cap-ture Process under a Seasonal Variation in NaturalRecharge and Discharge, Hydrogeol. J., 1998, vol. 6,pp. 24–32.
WATER RESOURCES Vol. 36 No. 6 2009
GROUNDWATER RECHARGE: A HYDROGEOLOGIC THOUGHT 631
32. Mau, D. and Winter, T., Estimating GroundwaterRecharge from Stream Flow Hydrographs for a SmallMountain Watershed in a Temporal Humid Climate,Groundwater (USA, New Hampshire), 1997, vol. 35, no.2, pp. 291–304.
33. Maxey, G.B., Hydrogeology of Desert Basins, Ground-water, 1968, vol. 6, no. 5, pp. 10–22.
34. Mayer, G.C. and Jones, L.E., SWGW—A Computer Pro-gram for Estimating Groundwater Discharge to StreamsUsing Stream Flow Data, USGS, WRI, 1996, pp. 96–4071.
35. McCord, J.T., Gotway, C.A., and Conard, S.H., Impactof Geologic Heterogeneity on Recharge EstimationUsing Environmental Tracers; Numerical ModelingInvestigation, Water Resources Res., 1997, vol. 33,pp. 1229–1240.
36. Mitchell-Bruker, S., Modeling Steady State Groundwa-ter Flow and Surface Water Interactions, Ph.D. Diss.,USA: Indiana University, School of Public and Environ-mental Affairs, 1993.
37. Moore, R.D. and Thompson, J.C., Are Water Table Vari-ations in a Shallow Forest Soil Consistent with the TOP-MODEL. Concept?, Water Resources Res., 1996,vol. 32, no. 3, pp. 663–669.
38. Muskat, M., The Flow of Homogeneous Fluids throughPorous Media, New York: McGrawHill, 1937.
39. Ophori, D.U. and Toth, J., Characteristics of Groundwa-ter Flow by Field Mapping and Numerical Simulation.Ross Creek Basin, Alberta, Canada, Groundwater, 1989,vol. 27, no. 2, pp. 193–201.
40. Padilla, A., Pulido-Bosch, A., and Mangin, A., RelativeImportance of Baseflow and Quickflow from Hydro-graphs of Karst Spring, Ground Water, 1994, vol. 32,no. 2, pp. 267–277.
41. Potter, K.W., Hydrological Impacts of Changing LandManagement Practices in a Moderate–Sized AgriculturalCatchment, Water Resources Res., 1991, vol. 27, no. 5,pp. 845–855.
42. Powers, G.J. and Shevenell, L., Transmissivity Estimatesfrom Well Hydrographs in Karst and Fractured Aquifers,Ground Water, 2000, vol. 38, no. 3, pp. 361–369.
43. Polubarinova-Kochina, P.Y., Theory of GroundwaterMeasurement, Russia, Moscow: Goste Khizdat, 1952.
44. Rorabaugh, M.I., Use of Water Levels in EstimatingAquifer Constants in Finite Aquifer, Int. Assoc. Sci.Hydrol., 1960, vol. 52, pp. 314–323.
45. Russo, D., Zaidel, J., and Laufer, A., Numerical Analysisof Flow and Transport in a Combined HeterogeneousVadose Zone—Groundwater System, Adv. WaterResources, 2000, vol. 24, pp. 49–62.
46. Rutledge, A.T., Computer Programs for Describing theRecession of Groundwater Discharge and for Estimating
Mean Groundwater Recharge and Discharge fromStream Flow Records, USGS, WRI, 1993, pp. 93–4121.
47. Rutledge, A.T, and Daniel, C.C., III, Testing an Auto-mated Method to Estimate Groundwater Recharge fromStream Flow Records, Groundwater, 1994, vol. 32,no. 2, pp. 180–189.
48. Sanford, W., Recharge and Groundwater Models: Anoverview, 2002, vol. 10, pp. 110–120.
49. Scanlon, B.R., Healy, R., and Healy, P., ChoosingAppropriate Techniques for Quantifying GroundwaterRecharge, Hydrogeology J., 2002, vol. 10, no. 1, pp. 8–39.
50. Shaman, J.M., Stielblitz, V.E., Kestev, R., and Stark, C.,Representation of Subsurface Storm Flow and MoreResponsive Water Table in a TOPMODEL—BasedHydrology Model, Water Resources Res., 2002, vol. 38,no. 8, pp. 1156–1172.
51. Shevenell, L., Analysis of Well Hydrographs in KarstAquifer: Estimates of Specific Yields and ContinuumTransmissivities, J. Hydrol., 1996, vol. 174, pp. 331–355.
52. Shirmohammadi, A., Kinsel, W.G., and Sheridan, J.M.,Regional Application of an Appropriate Stream FlowPartitioning Method, Water Resources Bull., 1987,vol. 23, no. 1, pp. 103–111.
53. Slitcher, C.S., Theoretical Investigation of the Motion ofGround Waters, USGS, 1898, 19th annual report.
54. Steuer, J.J. and Hunt, R.J., Use of Watershed—ModelingApproach to Assess Hydrologic Effects of Urbanization,North Fork Pheasant Branch Basin near Middleton,Reston, Virginia, Wisconsin: USGS, WRI, vol. 01-4113,2001.
55. Strack, O.D.L., Three Dimensional Streamlines inDupuit—Forchheimer Models, Water Resources Res.,1984, vol. 20, no. 7, pp. 812–822.
56. Subramanian, V., Water: Quality—Quantity Perspectivein South Asia, Surrey, U.K.: Kingston International Pub-lishers, 2000.
57. Tabbagh, A.B. and Benderitter, Y., Determination ofRecharge in Unsaturated Soils Using Temperature Mon-itoring, Water Resources Res., 1999, vol. 35, pp. 2439–2446.
58. Tada, A., On the Compaction Curve of the Kante—Loamand Its Permeability, vol. 1, Trans. Agric. Eng. Soc. Jpn.,1965, vol. 14, pp. 36–40.
59. Toth, J., A Theoretical Analysis of Groundwater Flow inSmall Drainage Basins, J. Geophys. Res., 1963, vol. 68,no. 16, pp. 4795–4812.
60. Vauclin., M., Khanji, D., and Vachaud, G., Experimentaland Numerical Study of a Transient, Two DimensionalUnsaturated. Saturated Water Table Recharge Problem,Water Resources Res., 1979, vol. 15, pp. 1089–1101.
61. Winter, T.C., The Concept of Hydrologic Landscapes, J.Am. Water Resource Assoc., 2001, vol. 37, pp. 335–349.
