Gec pest

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A.V.S.S.AnandScientist

Central ground Water BoardVisakhapatnam

([email protected])

GROUND WATER RESOURCE ASSESSMENT

PARAMETER ESTIMATION

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The Accuracy of Resources Estimation Depends on

The Methodology

The Data For That Particular Area

The Parameters/Norms Used In The Estimation.



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METHODOLOGYGEC-1997 Modifications by GEC-2004 Recommendations by R&D Advisory committee

The methodology theoretically is up to a certain level using which a realistic picture of the ground water scenario of any area

can be estimated .



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THE FIELD DATA

It is being collected and updated by

the user agencies.

The database at the user agencies

is also strong enough to implement

the methodology and come out with

realistic estimates.



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PARAMETERS USED IN THE ESTIMATIONThese are the crucial factors in deciding the accuracy of the estimation. Parameters used in the estimation are suggested based on the Ground Water Balance Projects and the studies carried out by Central and State Ground Water Organizations and Research and Academic institutions in India, There is no proper documentation specific to these norms is available today.



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Type Of Parameter

Parameter Unit

Storage Norm Specific Yield Percent

Infiltration Norms Rainfall Infiltration Factor Percent

Canal Seepage Ham/day/106m2 of wetted area.

Return Flow Factor For Irrigation Percent

Infiltration Factor For Tanks & Ponds

mm/day

Seepage Factor For Water Conservation Structures

Percent

Requirement Norms

Percapita Requirement For Domestic and Industrial Needs

lpcd

Abstraction Norm Unit Draft ham

Various Types Of Parameters Used In The Ground Water Resource Estimation Using GEC-1997.

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Specific Yield

Pumping Test Analysis

Slug Test Analysis

Volume Dewatering Method

Ramsahoye-Lang Analytical Method

Dry Season Ground Water Balance Method

Flow Net Analysis

Laboratory Methods

Simple Field Techniques

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Determination Of Specific Yield By Volume Dewatering Method

(After H.P.Jayaprakash et al)

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Determination Of Specific Yield By Volume Dewatering Method

(After H.P.Jayaprakash et al)

Volume of the Cone defined by the radius of influence

r=radius of influence 36.0mh=height of the cone 6.73mVolume Of The Cone Of Depression (V1)

Volume of Material Outside actual cone of depression (V2)

Average area outside cone of depression X Circumference of the circle with the radius equal to radius of influence

= Actual Volume of the Aquifer Dewatered V3=(V1-V2)

9137.417 –5674.608 = 3462.809

Volume of Water Pumped Out (measured using flow meter)( V4)

198.27

Specific Yield

hr2

3

1π

m32 417.913773.63614.33

1 =×××

m3608.56743614.322

2.50 =×××

m3

%72.5809.3462

100270.198100

3

4 =×=×V

V

m3

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Ramsahoye-Lang Analytical Method

This method which takes care of calculating the aquifer material dewatered.

The value computed by this method is more realistic than the conventional methods of analysis.

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Ramsahoye-Lang Analytical MethodDischarge =259.518 m3/day ; ∆S=0.5mT is calculated Using the Recovery Data

Computation Of Aquifer Material Dewatered

Where

T =Transmissivity =95m2/day , t=2000mts

R = distance from the pumping well to observation well = 10m

s = Average drawdown in all the observation wells at 10m = 1.08m

daymS

QT /95

5.014.34

518.25930.2

4

30.2 2=××

×=∆

=π

Q

Ts

TrQLogVLog

45.5

4

2

+

=

mV

LogVLog

3896.9749

989.31546.28344.1518.259

08.19545.5

380

1010518.259

=

=+=××+

××=

%7.3896.9749

100389.1518.259 =××=×=V

tQSY

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Specific Yield

S

QT

∆=

π4

30.2

Q

Ts

TrQLogVLog

45.5

4

2

+

=

V

tQSY

×=

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Dry Season Ground Water Balance Method1.

This approach is suitable in hard rock areas where data regarding base flow in the dry season is available or practically zero. The period from January to May or from March to May may be used for this exercise. The change in ground water storage in the dry season is given by the following equation.

h x Sy x A = DG - Rgw + B

where h = decrease in ground water level DG = gross ground water draft

Rgw = recharge due to ground water irrigation

B = base flow from the area Hence specific yield can be estimated based on the following

equation. y

G gwS

D R B

h xA=

− +

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Specific Yield

∑==∑=

××==××==

∑++

=

)*(

arg

3

2

1

321

AreahdDeasturateAquiferVolumeTotalVOutflowQ

nConsumptiocapitaPerDaysPopulationDraftDomesticQeDischUnithrswellsofNoDraftIrrigationQ

WhereV

QQQSY

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Specific Yield

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Construction of flow net

With the pre pumping level records, a water level elevation contour map is to be prepared.Distance Vs Drawdown graph of all wells to a desired time of 1000 or 10000mts or at equilibrium should be prepared. Equal drawdown contour map is prepared from this graph as a separate overlay. Pre pumping water level map is to be superimposed on equal drawdown contour map and the points of intersection of equal drawdown and water level contour are to be marked and the elevation of the intersection points are obtained. These intersection points are called potential points and equipotential contours are drawn by connecting the points of equal value. Flow lines are drawn perpendicular to the equipotential contours while adjusting the space between them so that the intersections will result in curvilinear square and the flow lines converge towards the pumping well.

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Calculating Transmissivity:

According to Darcy’s law the flow through a unit width of aquifer normal to the plane of figure through a single flow channel between the adjacent flow lines =∆Q=KIm.

Where K= Hydraulic Conductivity, I= Hydraulic Gradient and m = Spacing between flow lines. As the spacing between equipotential lines is l and the drop in head is ∆h the flow is

In the system of squares the ratio m/l=1. As the potential drop is

constant across each square ∆Q between adjacent flow lines is equal. If there are nf flow channels, then the total flow Q through a unit thickness of

the aquifer can be calculated using the following formula.

∆=∆l

mhKQ

daymnh

QKD

nhDKQ

aquiferofthicknessfullFor

l

masnhKQ

nl

mhKQ

QnQ

f

f

f

f

f

212.475.011

4.863

1

=×

×=∆

=∴

×∆××=

=

×∆=

×

∆=

∆×=

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Calculating Transmissivity:

The amount of water pumped during an aquifer test is derived (i) from the leakage within the zone of influence (QL) and (ii) From the

intercepted natural flow (QN) through the aquifer as long as unsteady

state continues.QP=QN+QL in the zone of influence.

The intercepted natural flow can be estimated using the following formula

Where KD=TransmissivityW= Width of zone of influence across the natural ground water flow in mI = Hydraulic gradient.QL = QP-QN=3.00-0.44=2.565lps

lpsKDWIQN 44.01004.239012.47 3 =×××== −

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Calculating Specific Yield

%310010620.0

1046144.0100

10620.0106)15.005.0(

10615.045.310613.03

1

3

1

10605.010613.01440

40000015.0

61441440

400004.8656.2

45.3)(10613.0

3

2

=×××=×=

×=×+=

×=×××=××=

×=×××=

××=

=××=

=×=

DewateredVolume

LeakageofVolumeYieldSpecific

DewateredVolumeTotal

hAreaPumpingToDueDewateredVolume

InfluenceOfAreaPumpingOfDaysofNoDayPerDeclineSeasonalDeclineNaturalToDueDewateredVolume

mLeakageTotal

mhDrawdownmLeakageOfArea

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5. Laboratory Methods:There are many types of Laboratory Techniques which basically

depend on the saturating the sample and draining to measure the drained water or the by weighing the samples. The most popular methods are 1. Simple Saturation and Drainage Method, 2. Centrifuge Moisture Equivalent Method, 3. Correlation With Particle Size Method. These methods basically give the specific yield of the sample at the laboratory and may not be accurate specific yield of the aquifer in the field.

6. Simple Field Techniques:

Some of the simple techniques used in field to measure the specific yield are Field Saturation Method, Sampling After Lowering of Water Table and Drainage Method, Recharge Method and etc. These also may not give accurate results in the field because of many assumptions and constraints.

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Rainfall Infiltration Factor

Water Level Response Analysis Method

Water Balance Method

Soil Moisture Balance Method

Base Flow Method

Well Hydrograph Analysis Method

Nuclear Methods

Infiltration Test Method

CRD Method

Empirical Methods

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Rainfall Infiltration Factor


Water Balance Method

Soil Moisture Balance Method

Base Flow Method


Nuclear Methods

Infiltration Test Method

CRD Method

Empirical Methods

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(Vedavati River Basin Project (1988) )From the Hydrograph the increment in the ground water body and the corresponding rainfall events with a reasonable time lag may be considered and the summed up recharge is to be correlated with the rainfall.

The change in ground water body is nothing but the change in water level multiplied by the specific yield of the aquifer.

Best-fit line is to be plotted and the equation indicates the relation between rainfall and the recharge.

Name Of The Site Rainfall(m) Recharge(m)

Chikkanikanhalli 0.388 0.095

0.011 0.009

0.137 0.019

0.215 0.042

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)23(26.0Re

)023.0(26.0Re

)26.0

006.0(26.0Re

006.026.0Re

−=

−=−=

−=

rfchmminor

rfch

rfch

rfch

( )( )

RainfallTotal

RechargeTotalFactoronInfiltrati

23mmrainfallstormwherever

2326.0RechTotal1

=

>

−×= ∑=

n

i

srf

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)23(26.0Re

)023.0(26.0Re

)26.0

006.0(26.0Re

006.026.0Re

−=

−=−=

−=

rfchmminor

rfch

rfch

rfch

( )( )

RainfallTotal

RechargeTotalFactoronInfiltrati

23mmrainfallstormwherever

2326.0RechTotal1

=

>

−×= ∑=

n

i

srf

Name Of The Site Rainfall(m)Recharge(m)

RFIF

Chikkanikanhalli0.751 0.17446 0.23

Jayasuvarnapura0.359 0.06344 0.18

Sira0.493 0.11024 0.22

Sanavasapuram0.213 0.02704 0.13

Hardgere0.234 0.0286 0.12

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Water Balance Method(UNDP, Ghaggar River Basin Project ,1985 )

P

GFactoronInfiltrati

LSGGQQETEPG

LGSGGQQETEP

ioio

ioio

=

−−−−−−+−=+++−+−++=

)()()(

)()()(

WhereP=PrecipitationGi=Ground Water Inflow

Go=Ground Water Outflow

E=EvaporationET=EvapotranspirationQi=Inflow Of River Water

Qo=Outflow of River Water

S= Change in Soil Moisture StorageG=Change in Ground Water StorageL=Change in Lake storage

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Water Balance Method(Vedavati River Basin Project ,1988 )

Total rainfall received in the catchment (MCM) 22127

Increment To Ground Water Storage (MCM) 1420

Ground Water Draft (MCM) 500

Natural ground Water Discharge (MCM) 206

Interflow (taken as 7% of the Total runoff) (MCM) 76

Ground water increment due to seepage from tanks and canals etc (MCM)

397

Evapotranspiration Losses suffered by Ground water body (taken as 1.5% of the total rainfall)(MCM)

332

Gross Recharge (MCM) 1420+500+206+76-397+332=2137

Infiltration factor %1010.022127

2137 ==

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Soil Moisture Balance Method(Thornthwaite’s book keeping method )

SRIAEP m∆+++=

Sm∆

Where P=RainfallAE=Actual Evapotranspiration =Change in Soil Moisture Storage

I=InfiltrationR=Surface Runoff

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Soil Moisture Balance Method The rainfall, runoff and PET data are prerequisite for this exercise. if the RF < PET then actual EVT losses will be equal to the RF if the RF >= PET then actual EVT losses will be restricted to PET. The balance of rainfall raises the soil moisture level to the field capacity. After meeting the soil moisture deficit, the excess rainfall over PET

becomes the moisture surplus. The saturated soil makes the moisture available for the EVT if rainfall is

below PET. The soil moisture is continuously depleted till it reaches the wilting point if

there is no further rainfall. If there is any soil moisture left at the end of the calendar year, it is carried

over to the next year. The surplus moisture results in surface runoff and ground water recharge. The actual recharge can be assessed only when the run off is gauged.

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Base Flow Method

Meyboom (1961) suggested a method of determining ground water recharge, which involves analysis of a part of the runoff hydrograph, represents ground water recession by applying Butler’s equation

cycle. log a toscorrespond increment or time0.1k Q when timek

t at time Qk

.given timeany at Discharge

10

2

01

/

1

2

====

=

Q

Where

kkQt

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Base Flow Method(After K.R.Karanth)

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−−

−== ∫ 10

3.2

10

3.2

2122

2

1

2121

ktkt

t

t

kkkkdQQ tv

The Volume of discharge Qv corresponding to a given recession is

given by the following equation

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−−

∞−−=

10

3.2

10

3.222 0

2121

kkk

kkkQtp

The total volume Qtp of baseflow that would be discharged during an

entire uninterrupted period of ground water recession can be computed

by integrating this from time t0 to infinity.

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−=

−−=

3.2

.10

10

3.2

21

0

0

21

2

2

kkQHence

unityequalskwhichin

kkkQ

tp

tp

in which the first term becomes extremely small at t2 →∞

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The difference between the total potential ground water

discharge at the beginning of the recession period and the amount of

actual ground water discharge gives the remaining potential ground

water discharge. The difference between the remaining potential

ground water discharge at the end of any base flow recession and the

total potential ground water discharge at the beginning of the next

recession is the measure of the recharge takes place between these

recessions (Meyboom, 1961).

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ehhhh tmm

α−×−=− )()( 0

The physical process of releasing water from the aquifer as base flow is described by Boussinesq equation. For the water table recession this equation can be rewritten as follows:

Whereh= water level at any time th0=water level at the start of recession

hm=Water level where rate of recession is zero

α=Recession coefficient

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Well Hydrograph Analysis Method(After K.R.Karanth)

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ehh tα−×= 0

( )( ) ( )( )

100Pr

(%)

`11

2

1

1

1

0

×=

×=

+×−+×= ∑ ∑

=

−

=

−+

necipitatio

onInfiltratiRateonInfiltrati

ShonInfiltrati

ehehh

c

n

i

n

i

tnt

nc

αα

If the values of h and h0 are taken with respect to

hm this equation becomes

The cumulative rise in water level (hc) due to

recharge and drainage is given by Degallier’s equation, which is given below.

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Nuclear Methods

Artificial Tritium Injection Technique developed by Zimmermann et al (1967) and Munnich (1968) can be used for the recharge measurement.

Tritium, a radioactive isotope of hydrogen is commonly used as a tracer in hydrogeological studies.

Tritiated water molecule (HTO) does not behave differently from the other water molecules in the hydrological cycle.

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Nuclear Methods

Tritium tagging method is based on the piston flow model for the movement of the moisture in the unsaturated zone of the soil.

The piston flow model assumes that the soil moisture moves down wards in discrete layers.

Any fresh layer of water added near the surface due to precipitation or irrigation would percolate by pushing on equal amount of water beneath it further down and so on

such that the moisture in the last layer in the unsaturated zone is added to the ground water regime.

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Nuclear Methods

Rangarajan et.al, NGRI has applied this technique in Aurepalli Watershed, Mehaboobnagar District, Andhra Pradesh.

Tritium was injected at a depth of 80cm during first week of June 1984 at 15 sites

Soil cores were recovered during last week of November and First week of December, 1984.

The rainfall in the intervening period was 541mm.

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Nuclear Methods

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Nuclear Methods The Depth Vs Tritium Activity Plot for one of the sites indicates that

the difference between the depth of injection and peak activity was 39.0mm.

The rainfall in the intervening period was 541mm. This indicates the recharge during this period due to the rainfall of

541mm is 39.0mm.Hence

%7100541

39 =×=RFIF

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Infiltration Test method Infiltration tests are conducted with double ring

infiltrometer or single ring infiltrometer. Double ring infiltrometer will give more accurate results

as it provides a water curtain to stop the horizontal dispersion of water.

Horton (1933) established an exponential relation between the rate of infiltration and time.

It starts with a maximum rate of infiltration f0 and falls

to a constant rate fc. The infiltration capacity curve

satisfies the equation.

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Infiltration Test method

.tan

00

0

vegetationandsoilondependingtConsk

rateonInfiltratiFinal

ttimeatrateonInfiltratiInitial

ttimeatrateonInfiltrati

where

fff

effff

c

t

kt

cct

=

=

=

=

×

−+=

−

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Infiltration Test method

is plotted against t and a straight line is fitted and used for computing the infiltration at any time.

But this infiltration factor is not the infiltration factor what is being used in calculating the recharge.

Hence there is a need to have a method to establish the rainfall factor what is being used in the assessment.

To achieve this one should measure the height of water refilled at the time of stabilization as I and the original height of water column in the inner ring is T then the infiltration factor will be .

− ff

ctlog

100×T

I

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Cumulative Rainfall Departure Method It is shown that the natural ground water level

Fluctuation is related to the departure of rainfall from the mean rainfall of the preceding time.

If the departure is positive there will be a rise in the water level

If it is negative there will be decline. Brendenkamp et al. (1995) defined CRD as follows

allraAverageR

RkRCRD

av

av

i

n

i

nni

avinf

11

1

=

−= ∑∑==

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Cumulative Rainfall Departure Method Y.Xu et al (2001) proposed a new formula, which

computes the CRD as given below.

conditionsboundaryaquiferindicatingallrathreszholdR

RRiR

RCRD

t

i

nt

i

nn

av

i

nni

inf

12

111

=

−−= ∑∑∑

===

( ) ( ) ( )

AreaAOutflowNaturalQ

eDischOutPumpingQYieldSpecificS

factoriltrationallrarwhere

ASQQCRDSrh

outi

pi

outipii

t

i

==

===

−−

=∆

arg

infinf

1

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Cumulative Rainfall Departure Method

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Empirical Methods

Chaturvedi Formula(1973)

Where W=Ground Water Recharge in mm P=Annual Rainfall in mm.

( )38193.134.0

−= PW

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Empirical Methods

Amritsar Formula(1973):

( )4.4066.125.0

−= PW

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Empirical Methods

Krishna Rao Formula(1970)

2000)600(35.01000600)400(25.0600400)400(20.0

>−×=<<−×=<<−×=

PWherePWPWherePWPWherePW

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Canal Seepage Factor

Pondinig Method

Inflow-Outflow Method

Water Level Fluctuation Analysis Method

Decomposition Of Stream Hydrograph Method

Ground Water Hydrograph Analysis Method

Radio Tracer Methods

Analytical Solutions

Empirical Methods

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Ponding Method

The water level observations are started when the water level reaches just above the full supply level of the channel.

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Ponding Method

The gauge readings are observed at the intervals of 15 to 30 mts Observations of time rate for the drop of water surface are continued till the water level falls far below FSL to determine the recession rate.

Two important factors in making the ponding loss measurements are

(i) the channel should remain wet for sufficient time before measurements are made to ensure that the seepage rate is not more than the normal rate.

(ii) Selection of the proper experimental reach, which is representative of the entire canal system.

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Ponding Method

20.64602

02.112.1 =×+

10656.06187.64

1062460552.1 ×=×

×××

56104

10656.0 =×

5601000106

10456 =××

Average Wetted perimeter at FSL(m) 1.12

Average Wetted perimeter at Drop Level (m) 1.02

Mean Wetted Area Of the Reach (m2)

Area of The Upstream Bund (m2) 0.30

Area of The Downstream Bund (m2) 0.37

Total Wetted Area(m2) 64.87

Amount Of Water Added to Bring back the Dropped Pond Water level to FSL on Stabilization of Losses (m3)

1.552

Time interval for the above losses (mts) 61

Losses in m3 /Million Square Meters Of Wetted Area/day

Losses in ham /Million Square Meters Of Wetted Area/day

Losses in mm/day

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Inflow-Outflow method

This is similar to the hydrologic balance method.

A canal segment is selected for studying the seepage losses.

The canal discharges at the starting point of the canal and the ending point of the canal are measured and the other inflow and out flow parameters are computed separately.

nEvaporatioallRaOutflowInflowech −+−= infargRe

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Inflow-Outflow method

10392.255233999

59885568

23399910 310624606012.693 ×==

−×××××

592.25104

10392.255 =×

92.255106

104592.25 =×

Discharge through the upstream Control Point Weir in lps (Q1)

3341.10

Discharge through the intermediate outlets and off- taking channels in lps (Q2)

2124.45

Discharge through the End Control Point Weir in lps (Q3) 523.53

Seepage Loss in lps (Q1-Q2-Q3) 693.12

Total Wetted Area(m2) 233999

Seepage Losses in m3 /Million Square Meters Of Wetted Area/day

Losses in ham /Million Square Meters Of Wetted Area/day

Losses in mm/day

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The Fluctuations measured in the observation wells located in the command area are multiplied with the specific yield to calculate the point recharge,

This is to be plotted and contoured. The average contour value is to be multiplied with

the area between those two contours. Such recharge volumes are summed up to get the

recharge due to the canal segment. This method is elaborated in the calculation of

infiltration from tanks/ponds with an example.

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Decomposition Of Stream Hydrograph Method(After Vedavati River Basin Project)

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The level of stream flow before the release of water into canal is the original base flow from the ground water system.

When there is release of water into the canal, the stream flow rises marginally

and when the irrigation waters are released the stream flows increase substantially

and finally it shows a declining trend till it reaches the original base flow level.

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The portion of the rising limb between the base flow level and the marginal increase can be attributed to the canal seepages

The portion between this point and sudden increase accounts for excess irrigation water reaching the stream.

The portion between the base flow level and the abrupt decline on the recession limb represents the discharging part of the ground water from the recharging component due to applied irrigation water.

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Ground Water Hydrograph Analysis Method(After Vedavati River Basin Project)

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The canal opened on 06/04/1977 and was closed on 16/04/1977. If the canal was not operated on 06/04/1977, the water level in the

well would have continued the same trend and hence extension of the trend indicates the bottom boundary for the canal influence.

The water level suddenly rises after on 16/04/1977 as the release of water for the irrigation was started.

Hence the trend as on 16/04/1977 would have continued, if there is no release of irrigation waters.

Hence extension of this trend before release of water becomes the top boundary of canal recharge.

The area between these two lines represents the canal recharge. This area multiplied by the specific yield will be the canal recharge.

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YieldSpecificS

AreaWettedW

CanalToDueechR

WhereminW

minRNorm

DaysOfNoSCanalTheOfLenthBoundariesTwoBetweenArea

R

Y

A

C

A

C

YC

===

=

××=

argRe

2

3

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Radio Tracer Method(After UNDP Ghaggar River Basin Studies )

Point dilution technique can be used to determine the seepage rates of the canals. A radioactive solution is injected uniformly into the entire volume of water of well or a piezometer near a canal. The concentration of the tracer decreases with time due to the horizontal flow through the well. The filtration velocity of the horizontal ground water flow in the absence of other disturbances such as vertical flow, density current and diffusion is given by the formula.

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Radio Tracer Method(After UNDP Ghaggar River Basin Studies )

The filtration velocity of the horizontal ground water flow in the absence of other disturbances such as vertical flow, density current and diffusion is given by the formula.

CC

t

WhereC

CFt

VV

rrr

f

01

2

0

2

1f

10

00

0

f

0

ln2

V

becomesequation above then the r of radius a has wellof piezometer theand r of radius a has probe theIf

2. toedapproximat becan α 10%, than more isscreen a of areaopen When the t.at timeion ConcentratTracer C

t at timeTracer ofion Concentrat InitialCC. toC from changesion concentratracer in which t interval Time t

well.of presence the todue lines flow of distrotionfor accounts which factor, correctionA αflow water ground dundisturbe

theofdirection thelar toperpendicu volumemeasuring theofsection CrossFplacetakeswelltheintracerofdilutionwhichinwaterofVolumeV

VelocityFiltrationV

ln

α

α

−=

==

==

===

=

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Analytical SolutionsAfter Jose Liria Montanes,2006)

canal.(m) thefromt measuremen theof Distance Rdatum.(m) a above R distance aat level water Groundh

Datum(m) a above canal in the level Water theofHeight HCanal(m) theofLength L

(m/day)ty Conductivi HydraulicK/daym3in Flowin LeakedQ

2

22

======

−=

WhereRhHKLQ

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Empirical Methods

Bharat(1970) has formulated the following equation for estimating the canal losses (refered By UNDP Ghaggar River Basin Studies)

DepthSupplyCanalDWidthBedCanalB

DBCKmCumecsinLossesSeepage

==

+=200

)( 3/2/

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Empirical Methods

Sehgal(1973) opined that the following equation developed at the Central Design Office at Punjab Irrigation Department would give the seepage losses

CumecsineDischCanalQ

MSMcumecsinLossSeepageR

QR

C

C

arg

/

4 0625.0

==

=

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Irrigation Return Flow Factor

Drum Culture Technique

Nuclear Methods

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This technique is basically on the ground water balance equation

mminonInfiltratiI

mminpirationEvapotranswithequatedbecanwhichUseeConsumptivCU

mminedWaterAppliW

mmindaccumulatecipitationP

Where

ICUWP

a

a

===

=

+=+

Pr

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Drum Culture Technique In this method, the paddy crop is raised under

controlled conditions in drum of standard size in representative paddy plots.

Drums of 0.9 X 0.9 X 1.0m dimension are widely used.

Two drums, one with the bottom open and the other with the bottom closed are sunk into the plot to a depth of 75cms.

Both are filled with the same soil to field level. In both the drums, all agricultural operations are carried out as the surrounding plot.

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Drum Culture TechniqueThe heights of the water columns in the drums are

maintained equal to the outside. Water levels in the drums are measured twice a day to

determine the water losses. Rainfall and Evaporation data are to be recorded in the

hydro meteorological station. The water loss from the drum with the closed bottom

gives the consumptive use, while that from the drum with open bottom gives the consumptive use plus infiltration.

Hence the difference in water applied gives the infiltration.

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Nuclear Methods:

Artificial Tritium Injection Technique developed by Zimmermann et al (1977) and Monich (1968) can be used for the estimation of Return flow factor for irrigation also.

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Infiltraction Factor For Tanks & Ponds

Hydrologic Balance Method


Flow Net Analysis Method


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nEvaporatio - Seepage Visible-Inflow StorageTank in Change on Infiltrati

onInfiltratinEvaporatio Seepage Visible StorageTank Final StorageTank InitialInflow

+=+++=+

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Hydrologic Balance MethodParameter Early

MonsoonMid

MonsoonLate

monsoonWater Spread Area (Thousand m2) 8.380 8.380 8.380

Tank Storage at the Beginning(TCM) 8.780 8.780 8.780

Inflow (TCM) - - 2.646

Total Storage (TCM) 8.780 8.780 11.433

Total Storage at the End (TCM) 0 0 0

Net Storage (TCM) 8.780 8.780 11.433

Evaporation (TCM) 0.920 0.860 0.845

Visible Seepage (TCM) 5.700 5.700 6.816

Recharge (TCM) 2.160 2.220 3.772

Recharge (m) 0.2578 0.2649 0.4501

No of days 35 38 33

Recharge (mm/day) 7.40 7.00 13.60

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Tank infiltration can be determined by application of hydrological balance equation.

The surface water inflow into the tank is input to the system

the outflow over the surplus weir and sluices, evaporation and any other visible seepages will contribute to the output to the system.

By measuring the change in the tank storage and visible seepage and evaporation losses the infiltration can be computed .

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In the command area of the tank number of key observation wells are to be established and monitored with respect to the storage in the tank.

The point recharge from each of the well is computed by multiplying the fluctuation with the specific yield of the formation and a contour map is prepared .

The area in between two successive contours is multiplied with the average contour value gives the recharge received in that particular zone.

Similarly recharge computed from all the zones are summed up to get the recharge due to tank storage.

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(After Vedavati Project,CGWB)

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Area Spread

yield Specific

Contour BoundLower of Value

Contour Bound Upper of Value

i neContour Zoin Area

nesContour Zo of No.n

Ponds and anksToDueRecharge

2argRe

2

A

R

i

T

1

1

Water

T

Where

Factorech

WSCC

W

SCCA

SCCAR

A

Y

L

U

A

n

iY

LUi

n

iY

LUiT

=

=

=

=

==

=

×

+×

=

×

+×=

∑

∑

=

=

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The top of the flow line and the position of the impermeable boundary are necessary for drawing the flow lines.

Care should be taken to maintain the same scale for both vertical and horizontal axes in drawing the flow net.

loss head Totalor Tank in the water stored of headh

squares. ofNumber or Drops Potential ofNumber s

Tubes Flowor Channels Flow ofNumber Nf

tyConductivi HydraulicK

tionBund/Forma eThrough th Seepage

===

==

=

N

Q

Where

hN s

N fKQ

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daymQ

m

N

daym

hN s

N fKQ

Flow

/30172.0225

308.01

5

/08.

1

=××=

===

=

=

2h

2s

3Nf

0K

:Bund The Through

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./042.0/10 342/10 6875.411061.68

70.35Factor argRe

/335.7015000469.01500)0291.00172.0(

/30291.0222

408.0

1

2h

22s

4Nf

/08.0K

2

:Formation TheThrough Flow

daymmdaymmdaymech

daymQ

daymQ

m

N

daym

hNs

N fKQ

=−×=−×=×

=

=×=×+=

=××=

===

=

=

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Liner(m). of Bottomat Water of Head Pressurehi

(m). lining earthen the of ThicknessLc

(m).Liner AboveDepthWater Hw

(m/day) Lining the Of tyConductivi Hydraulic SaturatedKc

)rate(m/day onInfiltrativi

===

==

−+=

Where

Lc

hiLcHwKcvi

Quantification of the Recharge due to Tank/Pond can be depicted in the conceptual model by Herman Bouwer, 1982.

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Infiltraction Factor For Water Conservation Structures





As far as the estimation of recharge is concerned, there is no difference in between a tank/pond and a water conservation structure. The only difference of interest is the norm recommended by the GEC-1997.

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Estimation Of Draft Parameters GEC-1997 methodology uses

only one draft parameter i.e. Unit Draft.

This depends on the type of the abstraction structure, Potentiality of the aquifer and availability of electricity where ever required.

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Unit DraftdaysofNodayainhrsPumpingofNohrmineDischDraftUnit ××= 3arg

Parameter Dug well With Pump

Recharge Area Discharge Area

Discharge (lps) 4 6

Discharge (m3/hr) 14.4 21.6

No of hours of Pumping per day

2 4

Discharge per day (m3/day)

28.8 86.4

No of such days 120 120

Annual Draft (m3/year)

3456 10368

Unit Draft (ham) 0.3456 1.0368

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Percapita Requirement For Domestic And Industrial Needs

Purpose Recommended Minimum

(liters/person/day)

Drinking Water 5

Sanitation Services 20

Bathing 15

Cooking and Kitchen 10

Total Recommended Basic Water Requirement

50

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Gec pest

Technology

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