Gec pest

1
GEC-PESTGEC-PEST
By
A.V.S.S.Anand
Scientist
Central ground Water Board
Visakhapatnam
(avssanand@yahoo.com)
GROUND WATER RESOURCE ASSESSMENT
PARAMETER ESTIMATION

2
GEC-PESTGEC-PEST
The Accuracy of Resources Estimation
Depends on
The Methodology
 The Data For That Particular Area
The Parameters/Norms Used In The
Estimation.

3
GEC-PESTGEC-PEST
METHODOLOGY
GEC-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 .

4
GEC-PESTGEC-PEST
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.

5
GEC-PESTGEC-PEST
PARAMETERS USED IN THE ESTIMATION
These 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.

6
GEC-PESTGEC-PEST GROUND WATER RESOURCE ASSESSMENT
Type Of
Parameter
Parameter Unit
Storage Norm Specific Yield Percent
Infiltration Norms Rainfall Infiltration Factor Percent
Canal Seepage Ham/day/106
m2
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.

7
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

8
Determination Of Specific Yield By Volume Dewatering Method
(After H.P.Jayaprakash et al)

9
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 36.0m
h=height of the cone 6.73m
Volume 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
hr
2
3
1
π
m
32
417.913773.63614.3
3
1
=×××
m3608.56743614.32
2
2.50
=×××
m3
%72.5
809.3462
100270.198
100
3
4
=
×
=×
V
V
m3

10
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.

11
Ramsahoye-Lang Analytical Method
Discharge =259.518 m3
/day ; ∆S=0.5m
T 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
daym
S
Q
T /95
5.014.34
518.25930.2
4
30.2 2
=
××
×
=
∆
=
π
Q
Ts
T
rQ
LogVLog
45.5
4
2
+





=
mV
LogVLog
3
896.9749
989.31546.28344.1
518.259
08.19545.5
380
1010518.259
=
=+=
××
+




 ××
=
%7.3
896.9749
100389.1518.259
=
××
=
×
=
V
tQ
SY

12
Specific Yield
S
Q
T
∆
=
π4
30.2
Q
Ts
T
rQ
LogVLog
45.5
4
2
+





=
V
tQ
SY
×
=

13
Dry Season Ground Water Balance Method
1.
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 gw
S
D R B
h xA
=
− +

14
Specific Yield
∑==∑
=
××==
××==
∑
++
=
)*(
arg
3
2
1
321
AreahdDeasturateAquiferVolumeTotalV
OutflowQ
nConsumptiocapitaPerDaysPopulationDraftDomesticQ
eDischUnithrswellsofNoDraftIrrigationQ
Where
V
QQQ
SY

15
Specific Yield

16
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.

17
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
m
hKQ
daym
nh
Q
KD
nhDKQ
aquiferofthicknessfullFor
l
m
asnhKQ
n
l
m
hKQ
QnQ
f
f
f
f
f
212.47
5.011
4.863
1
=
×
×
=
∆
=∴
×∆××=
=





×∆=
×





∆=
∆×=

18
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=Transmissivity
W= Width of zone of influence across the natural ground water flow in m
I = Hydraulic gradient.
QL
= QP
-QN=3.00-0.44=2.565lps
lpsKDWIQN 44.01004.239012.47 3 =×××== −

19
Calculating Specific Yield
%3100
10620.0
1046144.0
100
10620.0106)15.005.0(
10615.045.310613.0
3
1
3
1
10605.010613.0
1440
40000
015.0
6144
1440
400004.8656.2
45.3)(
10613.0
3
2
=×
×
×
=×=
×=×+=
×=×××=××=
×=×××=
××=
=
××
=
=
×=
DewateredVolume
LeakageofVolume
YieldSpecific
DewateredVolumeTotal
hAreaPumpingToDueDewateredVolume
InfluenceOfAreaPumpingOfDaysofNoDayPerDeclineSeasonalDeclineNaturalToDueDewateredVolume
mLeakageTotal
mhDrawdown
mLeakageOfArea

20
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.

21
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

22
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

23
Water Level Response Analysis
Method
(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

24
Method
)23(26.0Re
)023.0(26.0Re
)
26.0
006.0
(26.0Re
006.026.0Re
−=
−=
−=
−=
rfch
mminor
rfch
rfch
rfch
( )( )
RainfallTotal
RechargeTotal
FactoronInfiltrati
23mmrainfallstormwherever
2326.0RechTotal
1
=
>
−×= ∑=
n
i
srf

25
Method
)23(26.0Re
)023.0(26.0Re
)
26.0
006.0
(26.0Re
006.026.0Re
−=
−=
−=
−=
rfch
mminor
rfch
rfch
rfch
( )( )
RainfallTotal
RechargeTotal
FactoronInfiltrati
23mmrainfallstormwherever
2326.0RechTotal
1
=
>
−×= ∑=
n
i
srf
Name Of The Site Rainfall(m)
Recharge(m)
RFIF
Chikkanikanhalli
0.751 0.17446 0.23
Jayasuvarnapura
0.359 0.06344 0.18
Sira
0.493 0.11024 0.22
Sanavasapuram
0.213 0.02704 0.13
Hardgere
0.234 0.0286 0.12

26
Water Balance Method
(UNDP, Ghaggar River Basin Project ,1985 )
P
G
FactoronInfiltrati
LSGGQQETEPG
LGSGGQQETEP
ioio
ioio
=
−−−−−−+−=
+++−+−++=
)()()(
)()()(
Where
P=Precipitation
Gi
=Ground Water Inflow
Go
=Ground Water Outflow
E=Evaporation
ET=Evapotranspiration
Qi
=Inflow Of River Water
Qo
=Outflow of River Water
S= Change in Soil Moisture Storage
G=Change in Ground Water Storage
L=Change in Lake storage

27
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 %1010.0
22127
2137
==

28
Soil Moisture Balance Method
(Thornthwaite’s book keeping method )
SRIAEP m∆+++=
Sm∆
Where
P=Rainfall
AE=Actual Evapotranspiration
=Change in Soil Moisture Storage
I=Infiltration
R=Surface Runoff

29
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.

30
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.logatoscorrespondincrementor time0.1kQwhentimek
tat timeQk
.given timeanyatDischarge
10
2
01
/
1
2
==
=
=
=
Q
Where
k
k
Q t

31
Base Flow Method
(After K.R.Karanth)

32
Base Flow Method
(After K.R.Karanth)





−
−




−
==
∫ 10
3.2
10
3.2
2122
2
1
2121
ktkt
t
t
kkkk
dQQ tv
The Volume of discharge Qv
corresponding to a given recession is
given by the following equation

33
Base Flow Method
(After K.R.Karanth)





−
−





∞
−
−=
10
3.2
10
3.2
22
0
2121
k
kk
k
kk
Qtp
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.

34
Base Flow Method
(After K.R.Karanth)






−=





−
−=
3.2
.10
10
3.2
21
0
0
21
2
2
kk
QHence
unityequalskwhichin
k
kk
Q
tp
tp
in which the first term becomes extremely small at t2 →∞

35
Base Flow Method
(After K.R.Karanth)
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).

36
Well Hydrograph Analysis Method
ehhhh t
mm
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:
Where
h= water level at any time t
h0
=water level at the start of recession
hm
=Water level where rate of recession is zero
α=Recession coefficient

37
(After K.R.Karanth)

38
ehh tα−
×= 0
( )( ) ( )( )
100
Pr
(%)
`
11
2
1
1
1
0
×=
×=





 +×−+×= ∑ ∑=
−
=
−
+
necipitatio
onInfiltrati
RateonInfiltrati
ShonInfiltrati
ehehh
c
n
i
n
i
t
nt
nc
α
α
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.

39
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.

40
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.

41
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.

42
Nuclear Methods

43
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
%7100
541
39
=×=RFIF

44
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.

45
.tan
0
0
0
vegetationandsoilondependingtConsk
rateonInfiltratiFinal
ttimeatrateonInfiltratiInitial
ttimeatrateonInfiltrati
where
f
f
f
effff
c
t
kt
cct
=
=
=
=
×





−+=
−

46
 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 ct
log
100×
T
I

47
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
n
ni
av
inf
11
1
=
−= ∑∑ ==

48
 Y.Xu et al (2001) proposed a new formula, which
computes the CRD as given below.
conditionsboundaryaquiferindicatingallrathreszholdR
RR
iR
RCRD
t
i
n
t
i
n
n
av
i
n
ni
inf
1
2
111
=






−−= ∑∑∑ ===
( ) ( ) ( )
AreaA
OutflowNaturalQ
eDischOutPumpingQ
YieldSpecificS
factoriltrationallrar
where
ASQQCRDSrh
outi
pi
outipii
t
i
=
=
=
=
=
−−







=∆
arg
infinf
1

49

50
Empirical Methods
Chaturvedi Formula(1973)
 Where
 W=Ground Water Recharge in mm
 P=Annual Rainfall in mm.
( )38193.13
4.0
−= PW

51
Empirical Methods
Amritsar Formula(1973):
( )4.4066.12
5.0
−= PW

52
Empirical Methods
Krishna Rao Formula(1970)
2000)600(35.0
1000600)400(25.0
600400)400(20.0
>−×=
<<−×=
<<−×=
PWherePW
PWherePW
PWherePW




53
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

54
Ponding Method
The water level
observations are started
when the water level
reaches just above the
full supply level of the
channel.

55
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.

56
Ponding Method
20.6460
2
02.112.1
=×
+
10656.0
6187.64
1062460552.1
×=
×
×××
56
104
10656.0
=
×
5601000
106
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

57
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

58
Inflow-Outflow method
10392.255
233999
59885568
233999
10 310624606012.693
×==
−×××××
592.25
104
10392.255
=
×
92.255
106
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

59
Water Level Fluctuation Analysis Method
 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.

60
Decomposition Of Stream Hydrograph Method
(After Vedavati River Basin Project)

61
 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.

62
 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.

63
Ground Water Hydrograph Analysis Method

64
 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.

65
YieldSpecificS
AreaWettedW
CanalToDueechR
Where
minW
minR
Norm
DaysOfNo
SCanalTheOfLenthBoundariesTwoBetweenArea
R
Y
A
C
A
C
Y
C
=
=
=
=
××
=
argRe
2
3

66
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.

67
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.
C
C
t
Where
C
C
Ft
V
V
r
rr
f
0
1
2
0
2
1
f
10
00
0
f
0
ln
2
V
becomesequationabovethen the
rofradiusahaswellofpiezometertheandrofradiusahasprobetheIf
2.toedapproximatbecanα10%,thanmoreisscreenaofareaopenWhen the
t.at timeionConcentratTracerC
tat timeTracerofionConcentratInitialC
C.toCfromchangesionconcentratracerin which tintervalTimet
well.ofpresencethetoduelinesflowofdistrotionforaccountswhichfactor,correctionAα
flowwatergrounddundisturbe
theofdirectionthelar toperpendicuvolumemeasuringtheofsectionCrossF
placetakeswelltheintracerofdilutionwhichinwaterofVolumeV
VelocityFiltrationV
ln
α
α
−
=
=
=
=
=
=
=
=
=

68
Analytical Solutions
After Jose Liria Montanes,2006)
canal.(m)thefromtmeasurementheofDistanceR
datum.(m)aaboveRdistanceaatlevelwaterGroundh
Datum(m)aabovecanalin thelevelWatertheofHeightH
Canal(m)theofLengthL
(m/day)tyConductiviHydraulicK
/daym3inFlowinLeakedQ
2
22
=
=
=
=
=
=







 −
=
Where
R
hHKLQ

69
Empirical Methods
Bharat(1970) has formulated the following equation for estimating
the canal losses (refered By UNDP Ghaggar River Basin Studies)
DepthSupplyCanalD
WidthBedCanalB
DBC
KmCumecsinLossesSeepage
=
=
+
=
200
)( 3/2
/

70
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
=
=
=

71
Irrigation Return Flow Factor
Drum Culture Technique
Nuclear Methods

72
Drum Culture Technique
This technique is basically on the ground water balance equation
mminonInfiltratiI
mminpirationEvapotranswithequatedbecanwhichUseeConsumptivCU
mminedWaterAppliW
mmindaccumulatecipitationP
Where
ICUWP
a
a
=
=
=
=
+=+
Pr

73

74
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.

75
The 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

76
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.

77
Infiltraction Factor For Tanks & Ponds
Hydrologic Balance Method
Flow Net Analysis Method

78
Hydrologic Balance Method
nEvaporatio-SeepageVisible-InflowStorageTankinChangeonInfiltrati
onInfiltratinEvaporatioSeepageVisibleStorageTankFinalStorageTankInitialInflow
+=
+++=+

79
Parameter Early
Monsoon
Mid
Monsoon
Late
monsoon
Water 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

80
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 .

81
 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.

82
(After Vedavati Project,CGWB)

83
AreaSpread
yieldSpecific
ContourBoundLowerofValue
ContourBoundUpperofValue
ineContour ZoinArea
nesContour ZoofNo.n
PondsandanksToDueRecharge
2
argRe
2
A
R
i
T
1
1
Water
T
Where
Factorech
W
S
C
C
W
SCCA
SCCAR
A
Y
L
U
A
n
i
Y
LU
i
n
i
Y
LU
iT
=
=
=
=
=
=
=








×






 +
×
=








×






 +
×=
∑
∑
=
=

84
Flow Net Analysis Method
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.
lossheadTotalorTankin thewaterstoredofheadh
squares.ofNumberorDropsPotentialofNumbers
TubesFloworChannelsFlowofNumberNf
tyConductiviHydraulicK
tionBund/FormaeThrough thSeepage
=
=
=
=
=
=
N
Q
Where
h
N s
N f
KQ

85
daymQ
m
N
daym
h
N s
N f
KQ
Flow
/30172.02
25
3
08.01
5
/08.
1
=××=
=
=
=
=
=
2h
2s
3Nf
0K
:BundTheThrough

86
./042.0/10 342/10 6875.41
1061.68
70.35
FactorargRe
/335.7015000469.01500)0291.00172.0(
/30291.02
22
4
08.0
1
2h
22s
4Nf
/08.0K
2
:FormationTheThroughFlow
daymmdaymmdaymech
daymQ
daymQ
m
N
daym
h
Ns
N f
KQ
=−×=−×=
×
=
=×=×+=
=××=
=
=
=
=
=

87
Analytical Solutions
Liner(m).ofBottomatWaterofHeadPressurehi
(m).liningearthentheofThicknessLc
(m).LinerAboveDepthWaterHw
(m/day)LiningtheOftyConductiviHydraulicSaturatedKc
)rate(m/dayonInfiltrativi
=
=
=
=
=
−+
=
Where
Lc
hiLcH w
Kcvi
Quantification of the Recharge due to
Tank/Pond can be depicted in the
conceptual model by Herman Bouwer,
1982.

88
Infiltraction Factor For Water Conservation Structures
Hydrologic Balance Method
Flow Net Analysis Method
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.

89
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.

90
Unit Draft
daysofNodayainhrsPumpingofNohrmineDischDraftUnit ××= 3
arg
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

91
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

92

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