This is the approved method using which the ground water resources of the country (India) are to be assessed. This is a modified version of GEC 1997 methodology. Presently all states are busy in assessing the Ground Water Resources for the base year 2016 using this methodology.
3. 3
Total Availability of Ground Water in an Area
Is sum of
Total Availability in Unconfined Aquifers
Total Availability in Semi-Confined Aquifers
Total Availability in Confined Aquifers
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
4. 4
Total Availability of Ground Water in an Area
In Hard Rock Areas
Deeper Aquifers are normally Semi-Confined
Recharge to the deeper aquifers is normally from the
top unconfined aquifer.
Unless and Until it is established that there is no
duplication of recharge estimation, recharge estimation
for deeper aquifers should not be carried out separately.
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
5. 5
Total Availability of Ground Water in an Area
In Soft Rock Areas
Some of the Deeper Aquifers are Semi-Confined
Recharge to some of the deeper aquifers is from the
top unconfined aquifer.
Where ever it is established that the recharge to the
deeper aquifer is from Top Unconfined Aquifer,
recharge estimation for those deeper aquifers should not
be carried out.
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
6. 6
If Aquifer Mapping is completed Resources
should be assessed for various aquifers.
else
Resources should be assessed upto 100m in hard
rock areas and 300m in soft rock areas.
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
7. 7
Total Availability of Ground Water in an
Aquifer
Is Sum of
Dynamic Ground Water Resource of that Aquifer.
Static / In-storage Ground Water Resource of that Aquifer.
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
8. 8
Dynamic Ground Water Resource
The Ground Water Resource which replenishes
every year.
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
9. 9
Static/ In-storage Ground Water Resource
The Ground Water Resource that is not replenished
every year.
The Ground Water that is available below the
Dynamic Zone.
That is available Below pre monsoon water level.
One Time Resource.
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
10. 10
Static/ In-storage Ground Water Resource
Because it is a one time Resource, It should not be
planned for development.
But in Severe drought Conditions, it can be exploited
for drinking purpose only with a plan to replenish the
resource in the coming excessive rainfall years.
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
11. 11
Estimation of Ground Water Resources
Based on
Ground Water Estimation Committee – 2015
Recommendations of R&D Advisory Committee
From Time to Time if any
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
12. 12
Areas where Principal
Aquifer is Alluvium
Administrative Boundaries
Areas where Principal
Aquifer is not Alluvium
Hydrological Boundaries
Ground Water Assessment Unit
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
13. 13
Hilly Areas Recharge is Not Possible
Ground Water Worthy Areas Recharge is Possible
Poor Ground Water Quality
Areas
Quality is Beyond Permissible
Limits
Good Ground Water Quality
Areas
Quality is Within Permissible
Limits
Command Areas Command of any Major or
Medium Irrigation Project
Non-Command Areas Not in the Command of any Major
or Medium Irrigation Project
Ground Water Assessment Sub-Units
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
14. 14
Predominant Monsoon South-West Monsoon
North-East Monsoon
Ground Water Year June To May
July To June
October To September
Monsoon Period June To September
July To October
October To December
June to December
Non-Monsoon Period October To May
November To June
January To September
December to May
Pre-Monsoon Monitoring May/June/September
Post-Monsoon Monitoring October/November/January
Ground Water Year
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
15. 15
Estimation of Ground Water Resources of
Unconfined Aquifer
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
18. 18
Inflow Components
Rainfall Recharge
Recharge From canals
Recharge From Surface Water Irrigation
Recharge From Ground Water irrigation
Recharge From Tanks & Ponds
Recharge From Water Conservation Structures
Lateral Inflow across Boundaries
Sub surface inflow from hydraulically connected streams
Vertical inter aquifer inflow
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
19. 19
Outflow Components
Gross Ground Water Extraction
Lateral Outflow across Boundaries
Sub surface Outflow from
hydraulically connected streams
Vertical inter aquifer Outflow
Evaporation
Transpiration
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
20. 20
THE MAIN COMPONENTS ARE
COMPUTATION OF GROUND WATER EXTRACTION
COMPUTATION OF RECHARGE DUE TO OTHER SOURCES
COMPUTATION OF INFLOWS/OUTFLOWS
COMPUTATION OF RAINFALL RECHARGE
COMPUTATION OF SUMMARY DETAILS
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
21. 21
COMPUTATION OF RECHARGE DUE TO OTHER SOURCES
Recharge Due To Canals
Recharge Due To Surface Water Irrigation
Recharge Due To Ground Water Irrigation
Recharge Due To Tanks & Ponds
Recharge Due To Water Conservation Structures
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
22. 22
COMPUTATION OF INFLOWS/OUTFLOWS
Lateral Flows across the Boundary
Vertical Inter Aquifer Flows
Stream Recharge/ Base Flow
Evaporation
Transpiration
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
23. 23
COMPUTATION OF SUMMARY DETAILS
Annual Extractable Ground Water Resources
Current Stage Of Ground Water Extraction
Validation of the Assessment by Water Level Trend
Categorization For Future Ground Water Extraction
Ground Water Allocation For Future Domestic Water Use
Net Annual Ground Water Availability For Future Use.
Additional Potential Resources.
In-Storage Ground Water Resources.
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
24. 24
COMPUTATION OF RESOURCES OF OTHER
AQUIFERS
Dynamic Ground Water Resources of Confined & Semi
Confined Aquifers in the Assessment unit.
Static/ In-storage Ground Water Resources of Confined &
Semi Confined Aquifers in the Assessment unit.
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
25. 25
Extraction Can Be Of Three Types
Domestic Extraction
Irrigation Extraction
Industrial Extraction
Estimation Of Ground Water
Extraction
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
26. 26
Estimation Of Ground Water
Extraction
GEALL = GEIRR + GEDOM + GEIND
Where,
GEALL=Ground water extraction for all uses
GEIRR=Ground water extraction for irrigation use
GEDOM =Ground water extraction for domestic uses
GEIND = Ground water extraction for industrial uses
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
27. 27
DOMESTIC EXTRACTION
Estimation Of Ground Water
Extarction
UNIT DRAFT METHOD
No. of different types of abstraction structures
Unit Draft
CONSUMPTIVE USE METHOD
Population Census
Consumptive Requirement
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
28. 28
IRRIGATION EXTRACTION
Estimation Of Ground Water
Extraction
UNIT DRAFT METHOD
No. of different types of abstraction structures
Unit Draft
CROP WATER REQUIREMENT METHOD
Cropping Pattern
Crop Water Requirement
POWER CONSUMPTION METHOD
Total power consumed
Ground Water extraction for Unit Power Consumption
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
29. 29
INDUSTRIAL EXTRACTION
Estimation Of Ground Water
Extraction
UNIT DRAFT METHOD
No. of different types of abstraction structures
Unit Draft
CONSUMPTIVE USE PATTERN METHOD
No. Industrial Units
Unit water Consumption
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
30. 30
Methods For Estimation
Estimation Of Ground Water
Extraction
Unit Draft Method
Crop Water Requirement Method
Power Consumption Method
Consumptive Use Method
Consumptive Use Pattern Method
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
31. 31
Where
GGWE = Gross Ground Water Extraction in any
season
No. = Number of Abstraction Structures
actually in Use.
Unit Draft = Draft For one abstraction structure
during the season.
Types = No of Types of Different Structures.
Unit Draft= Draft per day * No of days the
structures are in use
∑=
×=
types
i
DraftUnitNoGGWE
1
Unit Draft Method
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
32. 32
Estimation Of Ground Water
Extraction
Dug wells with Manual Lift : 989
Daily draft during non monsoon = 15m3/day
No of days 110
Dug wells with Electric Pumpset : 781
Daily draft during non monsoon = 65m3/day
No of days 87
What is the Unit Extraction During non-monsoon
Gross Ground Water Extraction
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
33. 33
Estimation Of Ground Water
ExtractionUnit draft during non monsoon
= 15 *110m3 =1650m3=0.165ham
Extraction From Dugwells with Manual Lift
=989 *0.165 =163.185ham
Dug wells with Electric Pumpset : 781
Unit draft during non monsoon
= 65 * 87 m3 =5655 m3 =0.5655ham
Extraction From Dugwells with Pumpset
=0.5655 *781 = 441.6555ham
Gross Ground Water Extraction For Irrigation
=163.185 + 441.6555 =604.84ham
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
34. 34
Where
GGWE = Gross Ground Water Extraction in any
season
Crops = No of Crops Grown in the Area.
Crop Water Requirement Method
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
∑=
×=
crops
i
iiIRR areacroppedtrequiremenwaterCropGGWE
1
35. 35
Estimation Of Ground Water
Extraction
Cropped Area Paddy: 360 acres
Crop Water Requirement For Paddy = 1.0m
Cropped Area Maize: 120 acres
Crop Water Requirement For Maize = 0.4m
What is the Ground Water Extraction for paddy and
Maize in hectare meters
1 acre= 0.404686 hectares
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
36. 36
Estimation Of Ground Water
Extraction
Ground Water extraction For paddy =
360 * 1.0* 0.404686 = 145.7 ham
Ground Water extraction For Maize =
120 * 0.4* 0.404686 = 19.4 ham
Gross Ground Water Extraction For Irrigation
=145.7 + 19.4 = 165.1ham
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
37. 37
Where
GGWE = Gross Ground Water Extraction in any
season
Sections = No of Electrical sections in the Area.
Power Consumption Method
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
∑=
×
=
tions
i i
i
liftwaterunitforrequiredpower
ConsumedPowerTotal
GGWE
sec
1
10000
38. 38
Estimation Of Ground Water
Extraction
Power required to lift 1 ham of water = 3 KWH
Total Power consumed in the Section = 420
units
What is the Ground Water Extraction in the above
section in hectare meters
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
39. 39
Estimation Of Ground Water
Extraction
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
Power required to lift 1 ham of water = 3 KWH
Total Power consumed in the Section = 420
units
Ground Water Extraction in the above section in
hectare meters = 420/3 =140 ham.
40. 40
Consumptive Use Method
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
100
*)(* rateGrowthyearCensusyearAssessmentP
PP C
CA
−
+=
Where,
PA
= Population as on Assessment year
PC
= Population as on Census year
10000
daysofNo.LgXtRequiremeneConsumptivXPopulation
=GE
×
41. 41
Estimation Of Ground Water
ExtractionPopulation as 2011 census = 12000
Population growth rate in the area =2%
Load on ground water for domestic needs =0.8
Consumptive requirement = 60lpcd
What is the Ground Water Extraction in the above
village during monsoon season of 120days
in hectare meters
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
42. 42
Estimation Of Ground Water
Extraction
Population as 2011 census = 12000
Population growth rate in the area =2%
Load on ground water for domestic needs =0.8
Consumptive requirement = 60lpcd
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
100
*)(* rateGrowthyearCensusyearAssessmentP
PP C
CA
−
+=
13200120012000
100
2*)20112016(*12000
12000 =+=
−
+=PA
43. 43
Estimation Of Ground Water
Extraction
Population as 2011 census = 12000
Population growth rate in the area =2%
Load on ground water for domestic needs =0.8
Consumptive requirement = 60lpcd
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
hamPA
6.7
10000000
1208.06013200
=
×××
=
10000000
daysofNo.LgXtRequiremeneConsumptivXPopulation
=GE
×
44. 44
Consumptive Use Pattern Method
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
∑=
××
=
types
1i
IND
10000
LginnConsumptiorUnit WateunitsindustrialofNumber
GE
meterscubic
Where,
Types= No of Different types of Industrial units
Lg = Fractional load on ground water for industrial water supply
What the Ground water extraction from an
assessment sub unit where there are 20 units of
packaged drinking water plant each plant’s water
consumption is 50000 m3
/day and load on ground
water is 0.75.
45. 45
Consumptive Use Pattern Method
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
∑=
××
=
types
1i
IND
10000
LginnConsumptiorUnit WateunitsindustrialofNumber
GE
meterscubic
Where,
Types= No of Different types of Industrial units
Lg = Fractional load on ground water for industrial water supply
ham75
10000
75.05000020types
1i
INDGE =
××
= ∑=
46. 46
COMMAND AREAS
SEEPAGE FROM CANALS
RETURN FLOW FROM SURFACE WATER IRRIGATION
RETURN FLOW FROM GROUND WATER IRRIGATION
RECHARGE DUE TO TANKS/PONDS
RECHARGE DUE TO WATER CONSERVATION STRUCTURES
Estimation Of Recharge Due To Other Sources
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
47. 47
NON-COMMAND AREAS
RETURN FLOW FROM SURFACE WATER IRRIGATION
RETURN FLOW FROM GROUND WATER IRRIGATION
RECHARGE DUE TO TANKS/PONDS
RECHARGE DUE TO WATER CONSERVATION STRUCTURES
Estimation Of Recharge Due To Other Sources
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
48. 48
Rc = WA*Days*SF
Where
Rc = The recharge due to canal segment in ham
WA=Wetted Area in Million Sq.m
SF = Seepage Factor in ham/Million Sq.m/day
Estimation Of Recharge Due To Canals
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
53. 53
ASD =Average Supply Depth
(Or 0.6*FSD)
θ = Side Angle
Estimation Of Recharge Due To Canals
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
54. 54
Where
WP=Wetted perimeter in m
ASD = Average Supply Depth in m
SideAngle = Side slope of the canal in Degrees
BW = Bed width of the canal in m.
BW
SideAngleSin
ASD
WP +=
)(
*2
Estimation Of Recharge Due To Canals
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
55. 55
WA= WP* L
Where
WA =Wetted Area in Million Sq.m
WP =Wetted perimeter
L = Length of Canal Segment in m.
Rc = WA*Days*SF
Where
Rc = The recharge due to canal segment in ham
WA=Wetted Area in Million Sq.m
SF = Seepage Factor in ham/Million Sq.m/day
Estimation Of Recharge Due To Canals
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
56. 56
NORMS FOR CANAL SEEPAGE
Estimation Of Recharge Due To Canals
Formation Canal Seepage factor ham/day/million
Square meters of wetted Area
Recommended Minimum Maximum
Unlined canals in normal soils
with some clay content along with
sand
17.5 15 20
Unlined canals in sandy soil with
some silt content
27.5 25 30
Lined canals in normal soils with
some clay content along with sand
3.5 3 4
Lined canals in sandy soil with
some silt content
5.5 5 6
All canals in hard rock area 3.5 3 4
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
57. 57
Canal reach Name – Nandgaon Minor
Reach Type – Unlined
Lithology – Hard Rock
Length –3560m
Full Supply Depth – 6m
Bed Width – 4m
Slope – 45°
Monsoon Running Days – 50
Non-monsoon Running Days -110
Canal Seepage Factor – 3.5 ham/day/million sq.m during
both monsoon & non-monsoon
What is the Recharge Due to The Canal reach ?
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
58. 58
What is the Recharge Due to The Canal reach ?
WA= 14.18 * 3560 = 50480.8 sq.m = 0.05048 m sq.m
Rc during monsoon = 0.05048 * 50 * 3.5 = 8.83 ham
Rc during non - monsoon = 0.05048 * 110 * 3.5= 19.43 ham
Annaul Rc = 8.83 + 19.43=28.26 ham
m
Sin
WP 18.14418.104
7071.0
2.7
4
)45(
6.0*6*2
=+=+=+
°
=
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
59. 59
Rswi = IWA * RFF
Where
Rswi = Recharge due to Surface water irrigation in
ham
IWA = Irrigation water applied in ham
RFF = Return Flow Factor as a fraction
IWA = AD *days
Where
IWA = Irrigation water applied in ham
AD = Average Discharge of the outlet in ham/day
Days = No of days the out let is open.
Estimation Of Recharge Due To Surface Water
Irrigation
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
60. 60
NORMS FOR SURFACE WATER IRRIGATION RETURN FLOW
Estimation Of Recharge Due To Surface Water
Irrigation
DTW
m bgl
Ground Water Surface Water
Paddy Non Paddy Paddy Non Paddy
<=10 45 25 50 30
11 43.3 23.7 48.3 28.7
12 41.7 22.3 46.7 27.3
13 40 21 45 26
14 38.3 19.7 43.3 24.7
15 36.7 18.3 41.7 23.3
16 35 17 40 22
17 33.3 15.7 38.3 20.7
18 31.7 14.3 36.7 19.3
19 30 13 35 18
20 28.3 11.7 33.3 16.7
21 26.7 10.3 31.7 15.3
22 25 9 30 14
23 23.3 7.7 28.3 12.7
24 21.7 6.3 26.7 11.3
>=25 20 5 25 10
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
61. 61
Estimation Of Recharge Due To Surface Water
Irrigation
Outlet Name – Nandgaon Minor OL-1
Canal Reach Name – Nandagaon Minor
Design Discharge – 1.846 ham/day
Monsoon Running Days – 50
Non-monsoon Running Days –110
Crop Type – Paddy
Area irrigated During Monsoon – 5000 ha
Area irrigated During Non-Monsoon – 5000 ha
Crop Type – Non-Paddy
Area irrigated During Monsoon – 7000 ha
Area irrigated During Non-Monsoon – 7000 ha
RFF for paddy during Monsoon - 0.5
RFF for Non- Paddy during Monsoon – 0.3
RFF for paddy during Non- Monsoon - 0.5
RFF for Non- Paddy during Non-Monsoon – 0.3
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
62. 62
Estimation Of Recharge Due To Surface Water
Irrigation
IWA During Monsoon = 1.846* 0.6 * 50 =55.38ham
IWA During Non-Monsoon = 1.846* 0.6 * 110 = 121.84ham
Rswi During Monsoon= 55.38 * 0.38 = 21.04 ham
Rswi During Non-Monsoon= 121.84 * 0.38 = 46.30 ham
AreaPaddyNonAreaPaddy
RFFPaddyNonAreaPaddyNonRFFPaddyAreaPaddy
RFFAverageWeighted
−+
−×−+×
=
38.0
12000
4600
12000
21002500
70005000
3.070005.05000
==
+
=
+
×+×
=RFFAverageWeighted
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
63. 63
Rgwi = IWA * RFF
Where
Rgwi = Recharge due to Ground water irrigation in ham
IWA = Irrigation water applied i.e. Gross ground Water
Draft in ham
RFF = Return Flow Factor as a fraction
Estimation Of Recharge Due To Ground Water Irrigation
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
64. 64
NORMS FOR GROUND WATER IRRIGATION RETURN FLOW
Estimation Of Recharge Due To Ground Water Irrigation
DTW
m bgl
Ground Water Surface Water
Paddy Non Paddy Paddy Non Paddy
<=10 45 25 50 30
11 43.3 23.7 48.3 28.7
12 41.7 22.3 46.7 27.3
13 40 21 45 26
14 38.3 19.7 43.3 24.7
15 36.7 18.3 41.7 23.3
16 35 17 40 22
17 33.3 15.7 38.3 20.7
18 31.7 14.3 36.7 19.3
19 30 13 35 18
20 28.3 11.7 33.3 16.7
21 26.7 10.3 31.7 15.3
22 25 9 30 14
23 23.3 7.7 28.3 12.7
24 21.7 6.3 26.7 11.3
>=25 20 5 25 10
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
65. 65
Estimation Of Recharge Due To Ground Water Irrigation
Crop Type – Paddy
Area irrigated During Monsoon – 5000 ha
Area irrigated During Non-Monsoon – 5000 ha
Crop Type – Non-Paddy
Area irrigated During Monsoon – 7000 ha
Area irrigated During Non-Monsoon – 7000 ha
RFF for paddy during Monsoon - 0.45
RFF for Non- Paddy during Monsoon – 0.25
RFF for paddy during Non- Monsoon - 0.45
RFF for Non-Paddy during Non-Monsoon – 0.25
Gross Ground Water Draft For Irrigation During Non-Monsoon= 165.5ham
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
66. 66
Estimation Of Recharge Due To Ground Water Irrigation
AreaPaddyNonAreaPaddy
RFFPaddyNonAreaPaddyNonRFFPaddyAreaPaddy
RFFAverageWeighted
−+
−×−+×
=
33.0
12000
4000
12000
17502250
70005000
25.0700045.05000
==
+
=
+
×+×
=RFFAverageWeighted
Rgwi During Non-Monsoon= 165.5 * 0.33 = 54.62 ham
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
67. 67
RT = AWSA * Days * RFact
Where
RT = Recharge from tanks & Ponds
AWSA = Average Water Spread Area.
(Or 60% of Design Water Spread Area.)
Days = No. of water is actually available in the Tanks &
Ponds.
RFact = A recharge Factor in mm/day
Estimation Of Recharge Due To Tanks & Ponds
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
68. 68
NORM FOR TANK & POND SEEPAGE
1.4 mm / day
Estimation Of Recharge Due To Tanks & Ponds
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
69. 69
Estimation Of Recharge Due To Tanks & Ponds
Tank Name – Yesamba
Design Water Spread Area – 55ha
Monsoon Running Days – 120
Non-monsoon Running Days –150
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
70. 70
Estimation Of Recharge Due To Tanks & Ponds
RT During Monsoon = 55 * 0.6 *120 * 0.0014 = 5.54 ham
RT During Non-Monsoon = 55 * 0.6 *150 * 0.0014=6.93 ham
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
71. 71
RWCS = GS*RFact
Where
RWCS = Recharge due to Water Conservation Structures
GS = Gross Storage
RFact = Recharge Factor as a Fraction
GS = Storage Capacity * No. Of Fillings
Estimation Of Recharge
Due To Water Conservation Structures
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
72. 72
NORM FOR SEEPAGE FROM WATER
CONSERVATION STRUCTURES
40% of Gross Storage during a year
means
20% during Monsoon Season
20% During Non-Monsoon Season
Estimation Of Recharge
Due To Water Conservation Structures
73. 73
Estimation Of Recharge
Due To Water Conservation Structures
WCS Name – Nandgaon
Type – Percolation tank
Storage Capacity – 5.7ham
No. of Fillings – 1.6
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
74. 74
Estimation Of Recharge
Due To Water Conservation Structures
RWCS During Monsoon = 5.7 * 1.6 * 0.20 = 1.82 ham
RWCS During Non-Monsoon = 5.7 * 1.6 * 0.20 = 1.82 ham
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
75. 75
LATERAL FLOW ALONG THE AQUIFER SYSTEM (THROUGH
FLOW)
BASE FLOW
STREAM RECHARGE
VERTICAL FLOW FROM HYDRAULICALLY CONNECTED
AQUIFERS
EVAPORATION
TRANSPIRATION
Estimation Of Inflows and Outflows
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
76. 76
If the area under consideration is a watershed, the lateral flow
across boundaries can be considered as zero in case such
estimates are not available.
If there is inflow and outflow across the boundary,
theoretically, the flow may be calculated using Darcy law, by
delineating the inflow and outflow sections of the boundary.
If it is estimated, it should be done for entire major aquifer in
all assessment units .
Lateral flow along the aquifer system (Through flow)
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
77. 77
Lateral flow along the aquifer system (Through flow)
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
78. 78
Lateral flow along the aquifer system (Through flow)
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
S.
No. Section No.
Ground Water head Contour in meters above
mean sea level During Monsoon Season
Distance
between the two
contours on
ground in
meters
Hydraulic
Gradient
(5)/(6)
Up Contour
(m)
Down Contour
(m)
Difference
(m)
(3)-(4)
(1) (2) (3) (4) (5) (6) (7)
1 1 225 221 2000
2 2 225 221 2000
3 3 221 217 2000
4 4 217 213 3500
5 5 213 209 3000
79. 79
Lateral flow along the aquifer system (Through flow)
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
S.
No. Section
Type
Ground Water head Contour in meters above
mean sea level During Monsoon Season
Distance
between the two
contours on
ground in
meters
Hydraulic
Gradient
(5)/(6)
Up Contour
(m)
Down Contour
(m)
Difference
(m)
(3)-(4)
(1) (2) (3) (4) (5) (6) (7)
1 Inflow 225 221 4 2000 0.002
2 Outflow 225 221 4 2000 0.002
3 Inflow 221 217 4 2000 0.002
4 Outflow 217 213 4 3500 0.0011
5 Outflow 213 209 4 3000 0.0013
80. 80
Lateral flow along the aquifer system (Through flow)
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
S.
No
.
Section
No.
Hydraulic
Gradient
Length of
the Section
in meters
Transmissivity
of the
unconfined
aquifer in the
section in
square meters
per day.
No of days
Water
flows
Across the
boundary
Ground Water
Flow Across the
boundary through
the section in
Hectare meters.
(1) (2) (3) (4) (5) (6) (7)
1 1 0.002 30000 60 120 +43.2
2 2 0.002 30000 60 120 -43.2
3 3 0.002 20000 60 120 +28.8
4 4 0.0011 15000 60 120 -11.88
5 5 0.0013 50000 60 120 -46.8
Ground Water Flow Across the boundary through all the
sections during Monsoon season in hectare meters. -29.88
81. 81
If stream gauge stations are located in the assessment unit, the
base flow can be computed using Stream Hydrograph Separation
method, Numerical Modelling and Analytical solutions.
If the assessment unit is a watershed, a single stream monitoring
station at the mouth of the watershed can provide the required
data for the calculation of base flow.
Any other information on local-level base flows such as those
collected by research centres, educational institutes or NGOs may
also be used to improve the estimates on base flows.
Base flow assessment should be carried out in consultation with
Central Water Commission in order to avoid any duplicity in the
estimation of total water availability in a river basin.
Base flow
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
82. 82
Base flow
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
S.
No.
Spell No. Start Day End Day No of Days
(4)-(3)
Discharge at
Start day in
cumecs
Discharge at
End day in
cumecs
Discharge
Difference in
cumecs
(7)-(6)
Slope of the
Discharge
Straight Line in
cumecs/day
(8)/(5)
(1) (2) (3) (4) (5) (6) (7) (8) (9)
1
2
3
83. 83
Base flow
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
S.
No.
Day Stream
Discharge in
cumecs
Direct Runoff
Spell No.
Discharge at
Start day in
the spell in
cumecs
Day No
in the
Spell
Slope of
Discharge
Straight line of
the Spell in
cumecs/day
Base Flow in
cumecs
Base Flow in ham
(8)*60*60*24/10-4
(1) (2) (3) (4) (5) (6) (7) (8) (9)
1
2
3
Total Base Flow Contributed at the stream gauge located at Upstream side Location During Monsoon Season in
ham
84. 84
This is estimated using Water Table Data and Stream Stage Data
using Darcy Law.
Estimation of Stream recharge should be carried out in
consultation with Central Water Commission in order to avoid
any duplicity in the estimation of total water availability in a river
basin.
Stream Recharge
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
85. 85
This can be estimated provided aquifer geometry and
aquifer parameters are known.
This can be calculated using the Darcy’s law if the
hydraulic heads in both aquifers and the hydraulic
conductivity and thickness of the aquitard separating
both the aquifers are known.
Ground water flow modelling is an important tool to
estimate such flows. As envisaged in this report
regional scale modelling studies will help in refining
vertical flow estimates.
Vertical Flow from Hydraulically Connected Aquifers
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
86. 86
Vertical Flow from Hydraulically Connected Aquifers
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
S.
No.
Sub Area
No.
Area in
Ha
Head
Difference in
meters
Thickness of
Aquitard in meters
Hydraulic
Conductivity of the
Aquitard in
meters/day
Vertical Inter Aquifer
Flow through the aquitard
in sub area in hectare
meters per day.
[(3)*(4)*(6)/(5)]
(1) (2) (3) (4) (5) (6) (7)
1 1 1000 4 35 0.025
2 2 500 3 35 0.025
3 3 2000 2 35 0.025
4 4 1000 1 35 0.025
5 5 1500 0.5 35 0.025
Vertical Inter Aquifer Flow through the aquitard from all sub areas during Non-Monsoon season in
hectare meters per day.
87. 87
Vertical Flow from Hydraulically Connected Aquifers
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
S.
No.
Sub Area
No.
Area in
Ha
Head
Difference in
meters
Thickness of
Aquitard in meters
Hydraulic
Conductivity in
meters/day
Vertical Inter Aquifer
Flow through the aquitard
in sub area in hectare
meters per day.
[(3)*(4)*(6)/(5)]
(1) (2) (3) (4) (5) (6) (7)
1 1 1000 4 35 0.025 2.857
2 2 500 3 35 0.025 1.071
3 3 2000 2 35 0.025 2.857
4 4 1000 1 35 0.025 0.714
5 5 1500 0.5 35 0.025 0.536
Vertical Inter Aquifer Flow through the aquitard from all sub areas during Non-Monsoon season in
hectare meters per day.
8.035
88. 88
It is recommended to compute the evaporation and Transpiration through
field studies.
If field studies are not possible for areas with water levels within 1.0
mbgl, evaporation can also be estimated using the evaporation rates
available for other adjoining areas.
Transpiration through vegetation can be estimated if water levels in the
aquifer with its capillary fringe are within the maximum root zone of the
local vegetation.
If field studies could not be done and water levels are within 2.0m bgl,
transpiration can be estimated using the transpiration rates available for
other areas.
Evaporation and Transpiration
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
89. 89
Evaporation
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
S.
No.
Evaporat
ing Zone
No.
Area in
hectares
Evaporation
Rate in
mm/day
Capillary
rise in the
zone in
meters
Average ground
water level in the
zone in meters
below ground level
No of days
Evaporation takes
place during
monsoon season
Evaporation from the zone
hectare meters.
(1) (2) (3) (4) (5) (6) (7) (8)
1 1 1000 2.0 1.0 0.75 120
2 2 2000 2.0 1.0 0.25 120
3
Evaporation through all the sections during Monsoon season in hectares meters.
90. 90
Evaporation
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
S.
No.
Evaporat
ing Zone
No.
Area in
hectares
Evaporation
Rate in
mm/day
Capillary
rise in the
zone in
meters
Average ground
water level in the
zone in meters
below ground level
No of days
Evaporation takes
place during
monsoon season
Evaporation from the zone
hectare meters.
(1) (2) (3) (4) (5) (6) (7) (8)
1 1 1000 2.0 1.0 0.75 120 6.00
2 2 2000 2.0 1.0 0.25 120 36.00
3
Evaporation through all the sections during Monsoon season in hectares meters. 42.0
91. 91
Transpiration
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
S.
No.
Transpirin
g Zone
No.
Area in
hectares
Transpiratio
n Rate in
mm/day
Average
root depth
in the zone
in meters
Capillary
rise in the
zone in
meters
Average ground
water level in the
zone in meters
below ground level
No of days
Transpiration takes
place during non-
monsoon season
Transpiration from the
zone hectare meters.
(1) (2) (3) (4) (5) (6) (7) (8) (9)
1 1 1000 1.0 2.5 1.0 2 120
2 2 2000 1.0 2.5 1.0 3 120
3 3
4 4
Transpiration through all the sections during Non-Monsoon season in hectares meters.
92. 92
Transpiration
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
S.
No.
Transpirin
g Zone
No.
Area in
hectares
Transpiratio
n Rate in
mm/day
Average
root depth
in the zone
in meters
Capillary
rise in the
zone in
meters
Average ground
water level in the
zone in meters
below ground level
No of days
Transpiration takes
place during non-
monsoon season
Transpiration from the
zone hectare meters.
(1) (2) (3) (4) (5) (6) (7) (8) (9)
1 1 1000 1.0 2.5 1.0 2 120 5.14
2 2 2000 1.0 2.5 1.0 3 120 3.43
3 3
4 4
Transpiration through all the sections during Non-Monsoon season in hectares meters. 8.57
93. 93
1.Rainfall infiltration factor method
2.Water level fluctuation method
Estimation Of Recharge Due To Rainfall
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
94. 94
Rainfall Infiltration Factor Method
Rrf = RFIF * A* (R – a)/1000
Where
a = Minimum threshold value in mm
It is suggested that 10% of Normal annual rainfall be taken as Minimum Rainfall
Threshold and 3000 mm as Maximum Rainfall limit. While computing the rainfall
recharge,
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
103. 103
Rainfall Infiltration Factor Method
Area 57580 ha
Raifall infiltration factor =0.07
Normal Monsoon Rainfall = 958mm
RRF = 57580 * 0.858*0.07 =3458.26 ham
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
104. 104
∆ S=h * SY * A
Where
∆S = Change in storage
h = Rise in water level in the
monsoon season
SY = Specified yield
A = Area of sub unit
Water Table Fluctuation Method
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
111. 111
S.No
Principal
Aquifer
Major Aquifers
Age
Recommended
(%)
Minimu
m
(%)
Maximu
m
(%)Code Name
61 Intrusive IN02
Ultra Basics (Epidiorite,
Granophyre etc.) -
Weathered, Jointed
Proterozoic
to Cenozoic 2 1 3
62 Intrusive IN02
Ultra Basics (Epidiorite,
Granophyre etc.) - Massive,
Poorly Fractured
Proterozoic
to Cenozoic 0.35 0.2 0.5
NORMS FOR SPECIFIC YIELD
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
112. 112
Water Table Fluctuation Method
Area 57580 ha
Specific yield – 0.02
Pre-Monsoon WL = 9.45
Post-Monsoon WL = 6.35
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
113. 113
Water Table Fluctuation Method
Area 57580 ha
Specific yield – 0.02
Pre-Monsoon WL = 9.45
Post-Monsoon WL = 6.35
∆ S=(9.45 – 6.35) * 0.02 * 57580=3569.96ham
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
114. 114
Hence
∆S= RRF+RSTR+RC+RSWI+RGWI+RTP+RWCS±VF ± LF -GE-T-E-B
Or
RRF =(h * SY * A)+ GE -RC - RSWI -RGWI – RTP – RWCS
–RSTR ±VF ± LF +T+E+B
Water Table Fluctuation Method
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
115. 115
Two Methods Can Be Employed
y=mx
Using y=mx+c equation
Normalization of Recharge Due To Rainfall During
Monsoon Season
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
117. 117
Normalization of Recharge Due To Rainfall During
Monsoon Season
y=mx
Rainfall Recharge
Recharge/Rainfall
(mm) (ham)
1434.8 1329.78
936.1 956.5
767 833.29
1164 1204.44
1016.18 1060.4
Normal Monsoon Season Rainfall = 1016.2mm
Normal Monsoon Season Recharge=
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
118. 118
Normalization of Recharge Due To Rainfall During
Monsoon Season
y=mx
Rainfall Recharge
Recharge/Rainfall
(mm) (ham)
1434.8 1329.78 0.93
936.1 956.5 1.02
767 833.29 1.09
1164 1204.44 1.03
1016.18 1060.4 1.04
1.022
Normal Monsoon Season Rainfall = 1016.2mm
Normal Monsoon Season Recharge=1016.2 * 1.022=1038.556
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
119. 119
Normalization of Recharge Due To Rainfall During
Monsoon Season
y=mx
Rainfall Recharge
Recharge/Rainfall
(mm) (ham)
1434.8 1329.78 0.93
936.1 956.5 1.02
767 833.29 1.09
1164 1204.44 1.03
1016.18 1060.4 1.04
1.022
Normal Monsoon Season Rainfall = 1016.2mm
Normal Monsoon Season Recharge=1016.2 * 1.022=1038.556
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
120. 120
For normalizing the rainfall recharge at least 5 years data of
rainfall and the corresponding rainfall recharge is used. Fitting a
linear regression curve for this data set will give an equation in
y=ax+b form
Where
r i= Rainfall
R i= Recharge due to rainfall
SS
SSS
N
N
a 2
13
214
−
−
=
N
a
b SS )( 12
−
=
∑=
=
N
i
irS 1
1 ∑=
=
N
i
iRS 1
2 ∑=
=
N
i
irS 1
2
3
∑=
=
N
i
ii RrS 1
4
Normalization of Recharge Due To Rainfall During
Monsoon Season
y=mx+c
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
129. 129
100
)(
)()(
×
−
=
rifm
rifmwtfm
PD
R
RR
Rf
RfRf
Where
PD = Percent Difference
RRf(wtfm) = Rainfall Recharge for normal monsoon
season rainfall estimated using Water Table
Fluctuation Method
RRf(rifm) = Rainfall Recharge for normal monsoon
season rainfall estimated using Rainfall Infiltration
Factor Method
PERCENT DIFFERENCE
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
130. 130
The rainfall recharge for Normal Monsoon
Season Rainfall is finally adopted as per the
following criteria.
If -20% < PD < +20% Final Rainfall Recharge = RRf(wtfm)
If PD < -20% Final Rainfall Recharge = RRf(rifm)*
0.8
If PD > +20% Final Rainfall Recharge = RRf(rifm)* 1.2
PERCENT DIFFERENCE
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
131. 131
TGWRm = RRf
+ RC
+ RSW
+ RGW
+ RT P
+ RWCS
+ RSTR ±VF ± LF –T-E-B
Where
TGWRm = Total Ground Water Recharge During Monsoon
RRF
= Recharge due to Rainfall
RC
= Recharge due to Canals
RSW
=Recharge due to Surface Water Irrigation
RGW
=Recharge due to Ground Water Irrigation
RT
=Recharge due to Tanks & Ponds
RWCS
=Recharge due to Water Conservation Structures
RSTR = Recharge due to hydraulically connected Streams
VF= Verical Flows from hydraulically connected aquifers
LF= Lateral Flows across boundaries
T = Transpiration
E= Evaporation
Total Ground Water Recharge During Monsoon Season
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
132. 132
Total Ground Water Recharge During Non-Monsoon Season
TGWRn = RRf
+ RC
+ RSW
+ RGW
+ RT P
+ RWCS
+ RSTR ±VF ± LF –T-E-B
Where
TGWRm = Total Ground Water Recharge During Monsoon
RRF
= Recharge due to Rainfall
RC
= Recharge due to Canals
RSW
=Recharge due to Surface Water Irrigation
RGW
=Recharge due to Ground Water Irrigation
RT
=Recharge due to Tanks & Ponds
RWCS
=Recharge due to Water Conservation Structures
RSTR = Recharge due to hydraulically connected Streams
VF= Verical Flows from hydraulically connected aquifers
LF= Lateral Flows across boundaries
T = Transpiration
E= Evaporation
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
133. 133
The sum of recharge during
Monsoon and Non-Monsoon
seasons will be the Total Annual
Ground Water Recharge.
Total Annual Ground Water Recharge
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
134. 134
EGR = TAGWR – EFLOW
Where
EGR = Annual Extractable Ground Water Resources
TAGWR = Total Annual Ground Water Recharge
EFLOW = Environmental Flows
(if not estimated 5% - 10% of Total Annual Ground Water Recharge)
Annual Extractable Ground Water Resources
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
135. 135
Stage Of Ground Water Extraction
100
usesallforextractionwatergroundgrossExisting
×=
ResourceswaterGroundeExtractablAnnual
(%)ExtractionWaterGroundofStage
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
136. 136
Validation
SOGWE Ground Water Level Trend Remarks
≤70% Significant decline in trend in both pre-monsoon and post-monsoon Not acceptable and needs
reassessment
>100% No significant decline in both pre-monsoon and post-monsoon long term trend Not acceptable and needs
reassessment
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
137. 137
Categorization of The Sub-Unit
Stage of Ground Water
Extraction
Category
≤70% Safe
>70%and ≤90% Semi-Critical
>90%and ≤100% Critical
> 100% Over Exploited
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
138. 138
Quality Tag For The Sub-Unit
If any of the three quality hazards in terms
of Arsenic, Fluoride and Salinity are
encountered in the assessment sub unit in
mappable units, the assessment sub unit
may be tagged with the particular quality
hazard.
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
139. 139
A = 22 * N * Lg
Where
A = Allocation for domestic water Requirement in
mm/year.
N = Projected Population density in the sub unit in
thousands per square kilometer.
Lg
= Fractional Load on ground water for domestic
and industrial water supply (≤ 1.0)
365*60lpcd=21900l/year =22 m3
/year
Allocation Of Ground Water For Domestic Needs
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
140. 140
Allocation Of Ground Water For Domestic Needs
Area 57580 ha
Population as on 2001 = 1,34,560
Population annual growth rate =2%
Dependency on ground Water = 0.9
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
141. 141
Allocation Of Ground Water For Domestic Needs
Projected Population as on 2025
= 134560+(134560*24*0.02)=134560 + 64589=199149
Population Density in thousands/sqkm
=199.149/575.8=0.3459
A = 22 * N * Lg
Allocation = 22*0.3459*0.9 =6.85mm/year
Allocation in ham = 57580*0.00685 = 394.423
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
142. 142
NAGWA = EGR – GEIRR- GEIND – AFDWR
Where
NAGWA = Net Annual Ground Water Availability For Future Use
EGR = Annual Extractable Ground Water Resource
GEIRR= Current Gross Extraction For Irrigation
GEIND = Current Gross Extraction for Industrial Needs.
AFDWR = Allocation For Future Domestic Water Requirement.
Net Annual Ground Water Availability For Future
Use
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
143. 143
1. Water logged and Shallow Water Table Areas.
2. Flood Prone Areas.
3. Spring Discharges
Additional Potential Recharges
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
144. 144
PRWL = (5-DTW)* A * SY
Where
PRWL = Potential Resource in Water Logged and Shallow
Water Table Areas
DTW = Average Depth To Water Level
A = Area of the Water logged Zone
SY
= Specific Yield in the zone upto 5.0m bgl.
Potential Resource In Water Logged And
Shallow Water Table Areas
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
145. 145
PRFL = 1.4 * N * A/1000
Where
PRFL = Potential Resource in Flood Prone Areas
N = No of Days Water is Retained in the Area
A = Flood Prone Area
Potential Resource In Flood Prone Areas
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
146. 146
Spring discharge constitutes an additional source of
ground water in hilly areas which emerges at the
places where ground water level cuts the surface
topography.
Spring discharge measurement is to be carried out by
volumetric measurement of discharge of the springs.
The committee recommends that in hilly areas with
substantial potential of spring discharges, the
discharge measurement should be made at least 4
times a year in parity with the existing water level
monitoring schedule.
Potential Resource Due to spring
Discharge
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
147. 147
Potential Resource Due to spring
Discharge
Potential ground water resource due to
springs = Q x No of days
Where
Q= Spring Discharge
No of days= No of days spring yields.
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
155. 155
Ground Water Resources of Confined and
Semi-confined Aquifer System
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
156. 156
Dynamic Ground Water Resources of the
Confined / Semi-Confined Aquifer System
It is to be computed only when the Particular
Aquifer is being exploited.
QD = SA∆h = SA (hPost – hPre)
Where
QD = Dynamic Ground Water Resource of Confined Aquifer (ham)
S = Storativity
A = Areal extent of the confined aquifer (ha)
∆h = Change in Piezometric head (m)
hpost =Piezometric head during post-monsoon period
hPRE = Piezometric head during pre-monsoon period
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
157. 157
In-storage Ground Water Resources of the
Confined / Semi-Confined Aquifer System
If the confined aquifer is being exploited for any purpose
QI= SA∆h = SA (hPRE – h0)
Where
QI =In storage Ground Water Resource of Confined Aquifer (ham)
S = Storativity
A = Areal extent of the confined aquifer (ha)
∆h = Change in Piezometric head (m)
h0 = Bottom level of the top Confining layer
hPRE = Piezometric head during pre-monsoon period
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
158. 158
In-storage Ground Water Resources of the
Confined / Semi-Confined Aquifer System
If the confined aquifer is not being exploited for any purpose
QI = SA∆h = SA (hpost - h0)
Where
QI = Instorage Resource of the confined aquifer(ham)
S = Storativity
A = Areal extent of the confined aquifer (ha)
∆h = Change in Piezometric head (m)
Hpost =Piezometric head during post-monsoon period
h0 = Bottom of the Top Confining Layer
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
159. 159
If the confined aquifer is being exploited, the Total
Ground Water Availability of the confined aquifer is
the sum of Dynamic Ground Water Resource and
the Instorage ground water resources of that
confined aquifer whereas if it is not being exploited,
the Total Ground Water Availability of the confined
aquifer comprises of only one component i.e. the
Instorage of the confined aquifer.
Total Ground Water Availability in Confined Aquifer
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
160. 160
GROUND WATER ASSESSMENT OF SEMI-
CONFINED AQUIFER SYSTEM
Unless and until, it is well studied that the recharge to this is
not computed either in the over lying unconfined aquifer or
underlying/overlying semi confined aquifers, it should not be
assessed separately.
As it is advisable to under estimate rather than to
overestimate the resources, it is recommended not to assess
these resources separately as long as there is no study indicating
its non-estimation.
If it is found through field studies that the resources are not
assessed in any of the aquifers in the area, these resources are to
be assessed following the methodology similar to that used in
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
161. 161
TOTAL GROUND WATER AVAILABILITY OF
AN AREA
The Total Ground water availability in any area is the
Sum of Dynamic Ground Water Resource, the
static/in-storage ground water resource in the
unconfined aquifer and the dynamic and In-storage
resources of the Confined aquifers and semi confined
aquifers in the area.
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
162. 162
Where the assessment unit is a watershed,
there is a need to convert the ground
water assessment in terms of an
administrative unit such as block/ taluka/
mandal/ Firka
Apportioning
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
163. 163
The ground water assessment in the sub units, non-command
and command areas of the watershed may be converted into
depth unit (mm), by dividing the annual recharge by the
respective area.
The contribution of this sub units of the watershed to the block,
is now calculated by multiplying this depth with the area in the
block occupied by this sub unit.
The total ground water resource of the block should be
presented separately for each type of sub unit, namely for non-
command areas, command areas and poor ground water quality
areas, as in the case of the individual watersheds.
Apportioning
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
164. 164
GROUND WATER ASSESSMENT IN URBAN AREAS
The difference of the actual demand and the supply by surface water
sources may be used as the withdrawal from the ground water resources.
It is proposed to use 30% of the rainfall infiltration factor for urban areas as
an adhoc arrangement till field studies in these areas are done and
documented field studies are available.
Because of the water supply schemes, there are many pipelines available in
the urban areas and the seepages from these channels or pipes are huge in
some areas. Hence this component is also to be included in the other
resources and the recharge may be estimated. The percent losses may be
collected from the individual water supply agencies, 50% of which can be
taken as recharge to the ground water system.
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
165. 165
GROUND WATER ASSESSMENT IN URBAN AREAS
In the urban areas in India, normally, there is no separate channels
either open or sub surface for the drainage and flash floods. These
channels also recharge to some extent the ground water reservoir.
Recharge Norm estimated for water supply channels may be used.
GEC2015GEC2015
GROUND WATER RESOURCES ESTIMATION
166. 166
GROUND WATER ASSESSMENT IN WATER LEVEL
DEPLETION ZONES
The reasons for this may be any one of the following : (a) There is a
genuine depletion in the ground water regime, with ground water
extraction and natural ground water discharge in the monsoon
season(outflow from the region and base flow) exceeding the recharge.
(b) There may be an error in water level data due to inadequacy of
observation wells.
If it is concluded that the water level data is erroneous, recharge
assessment may be made based on rainfall infiltration factor method.
If water level data is assessed as reliable, the ground water level
fluctuation method may be applied for recharge estimation.
The immediate conclusion from such an assessment in water depletion
zones will be that the area falls under the over-exploited category
which requires micro level study.
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167. 167
Ground Water Resources in Coastal Areas
The ground water resources assessment in coastal areas should be dealt
separately, because of the nature of hydraulic equilibrium of ground
water with sea water.
Wherever, the pre monsoon and post monsoon water levels are above
mean sea level the dynamic component of the estimation will be same
as other areas.
If both these are below sea level, the dynamic component should be
taken as zero. Wherever, the post monsoon water table is above sea
level and pre monsoon water table is below sea level the premonsoon
water table should be taken as at sea level and fluctuation is to be
computed.
The static or in storage resources are to be restricted to the minimum of
40 times the pre monsoon water table or the bottom of the unconfined
aquifer.
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168. 168
Micro Level Study for Notified Areas
Following approach may be adopted:
The area may be sub-divided into different hydrogeological sub-areas
The number of observation wells should be increased
Hydrological and hydrogeological parameters should be collected
Details regarding other parameters like seepage from canals and other surface
water projects should be collected after field studies.
The data of number of existing structures and unit draft should be reassessed
after fresh surveys .
All data available should be collected for the watershed/sub-areas
Ground water assessment for each sub-area may be computed using freshly
collected values of different parameters.
The ground water potential so worked out may be cross-checked with behaviour
of ground water levels
Based on the micro-level studies, the sub-areas within the unit and the unit as a
whole may be classified adopting norms for categorisation
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GROUND WATER RESOURCES ESTIMATION