Research Article ARTIFICIAL GROUND WATER … I/IJAET VOL I...International Journal of Advanced Engineering Technology E-ISSN 0976-3945 IJAET/Vol.I/ Issue II/July-Sept.,2010/150-164

International Journal of Advanced Engineering Technology E-ISSN 0976-3945

IJAET/Vol.I/ Issue II/July-Sept.,2010/150-164

Research Article

ARTIFICIAL GROUND WATER RECHARGE FIELD

STUDY : SITE CHARACTERIZATION AND TEST

RESULTS

1Prof. Pratima Patel,

2Dr. M. D. Desai

Address for correspondence 1Ph.D Research Scholar SVNIT, Surat & Asst. Prof. Civil Engineering Department, Sarvajanik

College of Engineering & Technology, Athwalines, Surat-395001, Gujarat, India,

E-mail [email protected] 2Ex. Prof. & Head, Applied Mechanics Department, S. V. National Institute of Technology,

Surat-395007, Gujarat, India,

ABSTRACT Over-exploitation of local ground-water resources can be prevented by inducing ground-water

mounding through artificial recharge using rain water stored in specially constructed basins. In

order to maintain the regional water balance and to assure optimal use of available water,

knowledge of the water-table fluctuation in response to the proposed recharged scheme is

essential. In this paper suitability of the site criteria for recharge bore well is discussed. Also

focused on collection of surrounding site geotechnical data, topography of the site, geometrical

parameters, evaluation of aquifer, and mathematics of ground water.

Mathematical modelling of ground water flow related to unconfined aquifer with a change in

saturated thickness with variation in Piezometric level, permeability, radius of influences or

distance between two recharge well and presence of recharge by rainfall is discussed here. By

using quadratic mathematical expression some significant relationship can be established.

Drawdown and detention time of water storage can also be determined. The technique is

implemented to an unconfined aquifer with horizontal impervious base receiving vertical

recharge using rain water stored in specially designed basin.

Authors have set up precast octagonal recharge well system at proposed site and suggested design

parameters for roof top rain water recharge system. Recharging capacity of well can be evaluated

by field test and confirmed with analytical solution.

Authors have established correlations between radius of bore well r and depth of pervious strata h

with capacity of borehole Qr which are adopted at site and gives satisfactory results, few are

highlighted.

KEYWORDS: unconfined aquifer, artificial recharges techniques, geometrical parameters,

radius of influence, draw down, Hypothesis of Water.

INTRODUCTION

Human health and welfare, food

security, industrial development and the

ecosystems on which they depend, are

all at risk, unless water and land

resources are managed more effectively

in the present decade and beyond. About

one-fifth of the world’s population lacks

access to safe drinking water and with

the present consumption patterns; two

out of every three persons on the earth

would live in water-stressed conditions



by 2025. With the growing demand of

water, recharging of aquifer is fulfilled

the need of the water crisis for future

generation.

Water is one of the renewable resources.

India with an average rainfall of 1150

mm is the second wettest country in the

world with good water resources. But

the water resources are not evenly

distributed over the country due to

varied Hydro geological conditions and

high variations in precipitation both in

time and space. As large quantities of

rainfall are going to sea as runoff, it is

better to harness this wasteful runoff by

adopting proper scientific conservation

measures and constructing suitable

recharge structures at appropriate

locations and artificially recharge the

depleted aquifers through recharge bore

wells. Added would be the tremendous

pressure to meet water requirements for

other purposes such as for industrial use,

environment and ecological management

etc. emanating from population growth,

the land use policies, degradation of

water resources and depletion of aquifers

in the country. [2]

RESEARCHERS VIEW

The problem of ground-water mound

formation below artificial recharge

basins has been investigated by many

researchers-Baumann (1952) Glover

(1960) Davis S. N. and Dewiest R. J. M.

(1966) highlight the methods of

recharging of various aquifers. Hantush

(1967) Hunt (1971) Bear J. (1979)

Warner et al. (1989), Bouwer H. (1989)

system for artificial recharge of aquifer

Basak (1982) has presented closed-form

analytical solutions of the Boussinesq

equation for mound build-up and

depletion in an island aquifer in response

to constant recharge and evaporation

over the entire aquifer. The water table

at the boundary of the aquifer is assumed

invariant with time. Zomorodi (1991)

has shown solutions For different one-

dimensional and two dimensional flow

models, Rai and Singh (1981, 1995) and

Rai et al. (1994) have also shown that

variations in the rate of recharge have

significant effects on the growth of

ground water mounds. Todd D.K. (2006)

illustrates how the recharging of aquifer

stops the salt water intrusion. I.S 15792

(2008) Artificial Recharge to Ground

Water– Guidelines mention the various

methodology installed at various site.

Design criteria for installing recharge

system are not highlighted. So at present

design procedure, system erection

method & implementation of artificial

recharge system is a today’s prime need.



Table 1: Location of G.W.L

Year Water level

1970 10 m below G. L.

1999 30 m - 60 m below G. L.

2050 80 m - 200 m below G. L. If not recharged now

Table 2: Depth of Sand below Water Table located surrounding Project Site.

Name of Site Depth of Sand

Strata (m)

Depth of Water Table

(m)

New Court Building 30 6

Tapi river - Amroli 30 6

Essar – Hazira 30 5

Weir cum Cause way 24 8

Kribhco – Jetty 35 6

Parle point 30 10

Puna Octroi Naka 20 10

Athwalines 21 16

Adajan 15 10

Ring road, station 32 20

V.N.S.G.U. 60 10

Varachha Bridge 25 13

SVNIT 35 6

Vesu ONGC 20 15

Table 3: Characteristics of Aquifer Materials

Material Porosity

n

Specific

yield % Sy

Permeability

k m/sec

Clay 0.45-0.55 01-10 10-10 to10

-6

Sand 0.35-0.40 10-30 10-5 to 10

-3

Gravel 0.30-0.40 15-30 10-4 to 10

-3

Sandstone 0.10-0.20 05-15 10-11 to 10

-8



POPULATION, WATER NEED AND

WATER AVAILABILITY [8]

The population of India is estimated to

reach a figure between 1.5 billion and

1.8 billion by the year 2050. The UN

agencies have put the figure 1.64 billion.

It is now generally accepted that the

countries with annual per-capita water

availability of less than 1,700 m3 are

water stressed and less than 1000 m3 as

water scarce. India would therefore need

2,788 billion cubic meters (b.c.m.) of

water annually by 2050 to be above

water stress zone and 1650 b.c.m. to

avoid being water scarce country.

The average annual surface water flows

in India has been estimated as 1869

b.c.m. of which 690 b.c.m. only can be

utilized. If appropriate storage

techniques can be created than

maximum water can be store. The

demand of water is increasing day-by-

day resulting in extraction of more and

more groundwater and such extraction is

in far excess of net average recharge

from natural sources and hence it

necessitates artificially recharging the

aquifers to balance the output.

Hypothesis of water available

In year 1970, water was freely available.

In year 1980, 50 paisa/glass. In year

1999 12 Rs./liter. In year 2050, may be

100 Rs./liter. [6] Thus, there is immediate

need to conserve every source of usable

water for the future generation. Planning

and management of 10 years could post

pone water crisis by few more years.

Ground Water Level in Past Tweenty

Years

Data are shown in Table 1

Table 4: Coefficient of Permeability for Various Sands

(USBR Earth manual, I.S. Code 1498)

Type of Sand Particle size Permeability k

(m/sec)

Sandy silt < 75 micron 2 x 10-6

Silty sand < 75 micron 5 x 10-5

Very fine sand 425 micron 2 x 10-4

Fine sand 425 micron –75 micron 5 x 10-4

Fine to medium sand 2 mm – 425 micron 1 x 10-3

Medium to coarse sand < 4.75 mm 2 x 10-3

Coarse sand and gravel 20 mm – 4.75 mm 5 x 10-3



LOCATION OF PROJECT SITE &

SITE CHARACTERIZATION

It reflects a detail of soil stratification 17

m depth of bore log soil classification &

its properties, depth of water table, depth

of pervious strata, and type of soil exist

at bed level. This exercise is required for

identification of soil aquifer.Also shows

Ground water level found at 11m from

G.L below this medium to coarse sand

available which is suitable for

recharging system. (Figure1).

Figure 1: Project Site AMD, SVNIT, SURAT Bore log Soil Stratification with recharge well

Figure 2: Map of Surat City (Project site)



EVALUATION OF SOIL AQUIFER

W.R.T. EXPLORATION DATA

(Figure 2 & Table 2).

Referring to geotechnical exploration

data of SVNIT project site and its

surrounding region following

observations are made:

• Up to 25-30 m depth sand strata

(SW-SM-SC-GM) available

below G.W.L. and below this

depth highly impervious soil

strata (MH-CH-CI) exists.

• A soil stratum below the well

casing is greater or equal to five

times diameter of bore well.

Depth of pervious soil strata ≥≥≥≥ 5 x d or

(10 x r)

• Water table = 11.4 m.

• Sand strata available in general

below G.W.L. up to 25 m

• Pervious Strata available at this

site is 25 – 11 = 14 m.

• 14 m ≥ 5 x 0.15 i.e. 14 m ≥

0.75 m

Above remarks fulfil the criteria of

unconfined aquifer so recharge problem

can be design and analyze under the

UNCONFINED AQUIFER category.

Figure 3:One-dimensional flow in an unconfined aquifer above an impervious base

Figure 4: Artificial Recharge by Fully Penetrating Recharge Wells in an

Unconfined Aquifer above an impervious base



Figure 5: Schematic lay-out of installation of precast octagonal step well

Figure 6: Recharge well with open bottom



GEOMATRICAL PROPERTIES OF

UNCONFINED AQUIFER

For designing any type of recharge

system geometrical properties of an

unconfined aquifer is required. Storage

function of aquifer material is depending

on: porosity, specific yield, retention,

storage coefficient, transmissibility,

permittivity & permeability.

(i) Porosity (n)

It is the ratio of the volume of voids

(pores) in soil mass to its total volume.

Coarse to medium sand : 0.26to 0.42

Fine Sand : 0.3 to 0.4

Sandy Gravel : 0.2 to 0.35

Uniformly graded sand has a higher

porosity than coarse sand.

(ii) Storage Co-Efficient

It is defined as the volume of water

released (or stored) by an aquifer per

unit surface area.

In an unconfined aquifer, it corresponds

to its specific yield.

For unconfined aquifers it range from

0.02 to 0.3

The actual values can be obtained from

the pumping out test.

(iii) Specific Retention (Sr)

It is ratio of the water retained to the

volume of aquifer. It depends on grain

size, shape, distribution of pores and

compaction of the soil formation.

For sand 10 to 30%,

For sandy Gravel 10 to 80%,

n = Sy + Sr (Table 3).

(iv) Specific Yield (Sy)

The volume of water, expressed as a

percentage of the total volume of

saturated aquifer, that can be drained by

gravity is called the specific yield.

Sand = 10% to 30%

Sandy Gravel = 15% to 25%

For unconfined aquifer Sy = 0.01 to 0.3

Specific yield depends upon - grain size,

shape and distribution of pores and

compaction of the formation.

(v) Permeability (k)

It is the ability of a formation to transmit

water through its pores when subjected

to a difference in water head. It has

dimension of velocity (m/sec). It is the

rate of flow per unit cross sectional area

under unit hydraulic gradient. (Table 4)

(vi) Transmissibility (T)

It is the discharge through unit width of

aquifer for the fully saturated depth

under unit hydraulic gradient. T is

directly varies with permeability and

saturated thickness of the aquifer.



T = k ⋅ b (m2/sec)

For unconfined aquifer

T = k ⋅ ba (m2/sec)

ba = average saturated thickness =

(H + h) / 2

H=height of original water table,h=

height of water in well after drawdown.

(vii) PERMITTIVITY (ΨΨΨΨ): The ratio

of permeability of soil (k) to thickness of

soil sample (dx) is known as

permittivity, measured in (sec)-1. It is

preferred measure of water flow capacity

across the soil mass.

Ψ = k/dx

Table 5: Qr = 15 x r x h

h(m)

r(m) 8m 10m 16m 18m 20m

Qr m3/hr

0.05 6 7.5 12 13.5 15

0.075 (SVNIT) 9 11.25 18 20.25 22.5

0.10 (Panas) 12 15 24 27 30

0.125 15 18.75 30 33.75 37.5

0.15 18 22.5 36 40.5 45

0.30 36 45 72 81 90

Table 6: Qr = 65 x d x k

k(m/hr)

d(m)

Fine Sand

(0.36 m/hr)

Coarse Sand

(3.6 m/hr)

More Coarser Sand

(3.96 m/hr)

0.15 (SVNIT) 3.5

m3/hr

35

m3/hr

38.61

m3/hr

0.25 5.85 58.5 64.31

0.30 7.0 70 77.22

0.60 14.0 140 154.4

0.90 21.0 210 231.7



MATHEMATICS OF GROUND

WATER FLOW-- UNCONFINED

AQUIFER

The flow of phreatic water in an

unconfined aquifer above an impervious

base is complicated by two factors: a

change in the saturated thickness

accompanying the variation in

Piezometric level and the presence of

recharge by rainfall. [3]

(Figure 3)

With the notation of Figure. 3 the

equations of flow becomes

Darcy dx

dhkhq −=

Continuity Pdx

dq=

Integrated 1CPxq += ….(i)

Put value of q in Eq.(i)kh dh/dx= Px+ C1

Combined

dxk

CPxhdh 1

+−=

Integrated

2

122Cx

k

2Cx

k

Ph +−−= ….(ii)

In which the integration constants must

be calculated from the boundary

conditions. (Figure 4) For the recharge

scheme of Figure 4 again consisting of

three wells fully penetrating the

saturated thickness of the aquifer, this

boundary condition gives

x = 0

2

2

n

2 Chh ==

It means that height of water table and

water mound is at same level

Put x = 0 in Eq. (i)

10 Cqq =−=

From which follows

Put x = maximum L, and values of C1,

C2, in Eq. (ii) we get

2

n022

0 hLk

2qL

k

Ph ++−= ……….….(1)

By the quadratic form of this equation,

finding a formula for the drawdown

n00 hhs −= …………………….….(2)

The design of an artificial recharge

scheme is mainly governed by: the time,

the water is meant to stay underground

and the amount of water that can be

stored in the aquifer. The design value of

detention time (T) during underground

flow determines the improvement in

water quality.

Tdays = p H L/ q0……………………….…….

(3)

The natural recharge by rainfall can be

calculated by,

q r = P x L…………………………(4)



ERRECTION OF RECHARGE WELL

WITH PRECAST OCTAGONAL STEP

WELL AT PROJECT SITE.

Please refer figure 5

TEST RESULTS

Evaluation of Recharging Capacity of

Design Well

Recharging capacity of Recharge bore

well with step well system installed at

site is evaluated as: 8000 liter water

from the tanker takes 15 minutes to

percolate in the soil strata through 0.15

m diameter & 15 m deep recharge bore

well.

Therefore,

Recharging capacity of design well=

8000lit./15min=533lit./min.=32 m3/ hr.

The overall recharging capacity of

installed recharge well at project site is

32 m3/ hr. It shows that in one hour

32,000 lit. water store in recharge well

without spill off.

Correlation Between r, h and Qr.

� Correlations between radius of bore

well (r) and depth of pervious strata

(h) with capacity of borehole (Qr)

(Figure 6)

Overall capacity of Borehole [1]

Qr = k A i t

Coarse sand permeability10-3m/sec=(3.6

m/hr)

Area of Borehole = 2πrh

Hydraulic gradient i = h/L = 20/30

Time = 1 hr

Qr = 3.6 x (2πrh) x h/L x 1

= 3.6 x (2πrh) x 0.67 x 1

Qr = 15 r h…………………………..(5)

(Table 5)

Estimation of Recharge Capacity

w.r.t. d and k

Flow qr by constant head recharge in

borehole.

qr = 2.75 x d x h x k [3]

Where,

d = diameter of bore (m)

h = depth of strata above the G.W.L (m)

= Maximum up to 25 m

k = co-efficient of permeability (m/sec)

qr = 2.75 x 25 x d x k

qr = 65 x d x k………………………..(6)

(Table 6)

� Constant value of bore diameter,

with decrease in permeability

recharges capacity reduces to 10

times.

� If we required more recharge rate

then provide larger diameter bore

instead of installing two smaller

diameter of bore. If the recharge

systems extend in fine sand (semi

pervious strata) (refer figure 1) then

10% recharge rate is added to the

original system in coarse sand.



Confirmation of Test Results for

SVNIT (SURAT, GUJARAT) Project

Site

Verifying recharge rate of installed

artificial recharge well system at SVNIT

by theoretical, experiment & design

table. [4]

�� qr = 30 m3/hr (Theoretically)

�� qr = 32 m3/hr (In-situ pumping in

recharge trial test)

�� qr = 35 m3/hr (Design table 6)

All three approaches give considerably

same value of recharge rate. So adopted

value of designed recharge rate is

confirmed.

Table 7: Recharged water Quality Analysis

S.

No.

Parameters Before Recharge One Year after

Recharge

Two Year

after Recharge

1. Rise of G.W.L. 10.5 m 9.9 m 8.0 m

2. pH 8.2 6.8 7.5

3. Chloride mg/l 550 90 30

4. Hardness mg/l 399 200 200

Figure 7: Recharge bore well system at Panas, Surat



CASE STUDIES

Recharge of groundwater through storm

run off and roof top. Water collection,

diversion and collection of run off into

dry tanks, play grounds, parks and other

vacant places are to be implemented by a

recharge well. Authors have suggested

(designed) different techniques at

various sites which are listed below.

Panas Recharge Bore Well: S.M.C.,

Surat. (Figure 7)

Adopting 1.5 m depth and 12 m wide

tank storage tank, 100 mm radius of P.

V. C. pipe, 12m - 20m sloughed pipes

and 20 - 22 cm Gravel pack [1] [9]

Recharge rate Qr= 5.5 x r x h x kav

= 5.5 x 0.1 x 18 x 10-3

= 35.6 m3/hr.

This implies that recharging capacity of

well is of 35.6 m3/hr.Cosidering amount

of recharge is 10 to 20 % of this means

35.6 x .2 = 28.48 m3/hr. Which is

confirmed with value of design Table 5

( 27 m3/hr ).

Botanical Garden SMC, SURAT.

Authors have given proposed design of

artificial recharge well of 0.45m

diameter & at 30m depth with bottom

packed with gravel for development of

garden connected with old bore well.

Provide Geo filter at inlet pipe of drain.

At top of tank RCC slab is constructed.

150 mm plain PVC pipe is installed as

recharge well up to 30m depth of

pervious coarse sand. (Figure 8, 9 & 10)

Figure 8Figure 8Figure 8Figure 8:::: Cross Section of Bore Log at Cross Section of Bore Log at Cross Section of Bore Log at Cross Section of Bore Log at

full depfull depfull depfull depth at th at th at th at Botanical Garden SMC Botanical Garden SMC Botanical Garden SMC Botanical Garden SMC

Surat Surat Surat Surat

Figure 9Figure 9Figure 9Figure 9:::: Plan & Section of proposed Plan & Section of proposed Plan & Section of proposed Plan & Section of proposed

GroundGroundGroundGround Water Recharging System Water Recharging System Water Recharging System Water Recharging System

at Botanical Gardenat Botanical Gardenat Botanical Gardenat Botanical Garden



Figure 10: Differential level Ground Water Recharging Scheme at Botanical

Garden SMC, Surat

S.V.R. College of Engg. & Tech,

Surat.

Ground Water Recharge Project:

Technique adopted is Recharge Well &

Bore.(Table 7 )

It show level of Groundwater is

increases and quality of Groundwater is

also improved after installing this

technique.

CONCLUSION

• Equation 5 gives design concept of

recharge well with knowing actual

value of depth of pervious strata for

the proposed site. Table 5 directly

gives relation of Qr with r and h.

• In other way, referring Table 5 if we

required higher rate of recharge than

installing one larger diameter well

instead of two smaller diameter well

which economies the project cost.

• Equation 6 shows recharge rate of

well directly varies with d and k.

Table 6 shows that with small

variation in aquifer permeability, the

recharge rate is drastically changed.

• If permeability of the aquifer is

known than only proper diameter of

well can be select from Table 6.

• From the equation 5 and 6 we can

justify that for installing recharge

bore well system permeability of

soil, diameter of recharge well, depth

of pervious strata are design

governing parameters.

REFERENCES

[1] Alamsingh, 1975, Soil Engineering in

Theory and Practice, Volume I Asia

Publishing House, Bombay, pp.128-129.

[2] Bear J., 1979, Hydraulics of Ground

Water, McGraw-Hill, New York,

pp.233-269.

[3] Huisman L., T. N. Olsthoorn, 1983,

“Artificial Groundwater Recharge”,



Pitman Advanced Publishing Program,

London, pp. 33-79.

[4] I.S.5529 Part I 1985, Indian Standard

Code of Practice for In-situ Permeability

Tests pp.6-12.

[5] James W. Warner, David Molden, 1989,

Mathematical Analysis of Artificial

Recharge from Basins Water Resource,

Bulletin 25, pp. 401-411.

[6] Patel Pratima, Desai M. D., 2008,

Analytical and Computational Aspect of

Artificial Ground Water Recharging into

Unconfined Aquifer, National

Conference on Bitcon Durg, M.P.

(India), pp. 16-19.


Numerical Modelling and Mathematics

of Ground Water Recharging --

Unconfined Aquifer, ACSGE

International Conference BITS Pilani,

Rajasthan. pp. 96–105.


Artificial Recharge of Ground Water by

Storm Water Reuse is Viable and

Sustainable Solution for Better

Tomorrow, 17th

IAHR-APD

International Conference, AUCKLAND

NEW ZEALAND Session: 6, Green

Devices 3, Paper No.5.

[9] USBR EARTH MANUAL PART I & II

1998, 3rd Edition Bureau of

Reclamation. pp.541-546.

Documents

Research Article ARTIFICIAL GROUND WATER … I/IJAET VOL I...International Journal of Advanced Engineering Technology E-ISSN 0976-3945 IJAET/Vol.I/ Issue II/July-Sept.,2010/150-164