ground water development

GROUNDWATER DEVELOPMENT

Introduction

Groundwater is a significant source of water supply for roughly half

of the country’s net irrigated area.  Groundwater irrigation (using dug

wells, bore wells, and dug- cum-bore wells) began to expand rapidly

with the advent of HYV technology in the second half of the 1960s.

according to estimates ( Dains & Power 1987) 70-80% of the value of

the irrigated agricultural production in the country may depend on

groundwater irrigation. Besides being a key contributor to agricultural

GDP, the spread of groundwater irrigation supports employment

generation and thus rural development and poverty alleviation.

 Groundwater resources availability in India

1. The groundwater resource has two components viz., instorage

and replenishable. The in-storage fresh

groundwater

resources i.e.(aquifer

zones below the zone of

water

table fluctuation) of the

country have been estimated

as

10812 billion m3

(1081.2 Mha-m).

The replenishable

component,which

is replenished annually, has been

assessed

as 432 billion m3

(43.2

Mha-m)

(CGWB, 1995).

As

per the

National Water Policy,

development of

groundwater

resources is to be limited

powaterlicy

therefore

forbids utilization of

in-storage resources to

prevent

groundwater mining.

After making a provision of

71.2

billion m3

(7.12 Mha-m)

for domestic,

industrial and

other

uses,

the available groundwater resource for

irrigation

is assessed as 360.8

billion m3

(63.08 Mha-m).

Based

on crop water requirements

and availability of

cultivable

land, utilizable irrigation potential has been

estimated

at 64 million ha. State- wise availability of

replenish

able groundwater, utilizable

irrigation potential

and

irrigation potential

created from groundwater

resources

are shown  

 Ground water: instorage, replenishable, available and draft

and irrigation potential

State Groundwater (Mha-m/year Irrigation potention (Mha)

Replenshible  Availabele Draft Utilizable Created Balance

Andhra pradesh 3.52916 2.99978 1.01318 3.9601 1.9290 2.0311

Arunachal Prades 0.14385 0.12227 ----- 0.0180 0.0021 0.159

Assam 2.47192 2.10113 0.13455 0.9000 0.1800 0.7200

Bihar 3.35213 2.84931 0.78108 4.9476 1.4276 3.5200

Goa 0.02182 0.01855 0.000219 0.0293 0.0017 0.0273

Gujarat 2.03767 1.73202 1.02431 2.7559 1.8406 0.9153

Haryana 0.85276 0.72484 0.86853 1.4616 1.5879 0.0000

Himachal Pradesh 0.03660 0.02929 0.00757 0.0685 0.0153 0.0532

Jammu & Kahmir 0.44257 0.37618 0.00713 0.7080 0.0129 0.6951

Karnataka 1.61857 1.37578 0.61443 2.5728 0.7284 1.8444

Kerala 0.79000 0.65868 0.14374 0.8792 0.1572 0.7220

Madhya Pradesh 5.08892 4.32560 1.01866 9.7325 1.8743 7.8582

Maharashtra 3.78673 2.54701 1.10576 3.6520 1.2901 2.3619

Manipur 0.31540 0.26810 ----- 0.3690 0.0004 0.3686

Meghanlaya 0.05397 0.04587 0.00260 0.0635 0.0092 0.0543

Mizoram ------- ------ ------- ----- -------

Nagaland 0.07240 0.06150 ------- ------- -----

Crissa 2.00014 1.700012 0.20447 4.2026 0.3931 3.8095

Punjab 1.86550 1.67898 2.25109 2.9171 5.1170 0.0000

Rajasthan 1.27076 1.0713 0.77483 1.7779 1.5052 0.2727

Sikkim ------ ----- -------- ------ -------

Tamilnadu 2.63912 2.24326 1.93683 2.8321 1.9631 0.8680

Tripura 0.06634 0.05639 0.02692 0.0806 0.0199 0.0607

Uttar Pradesh 8.38210 7.12467 3.83364 16.7990 14.0000 2.7990

West Bengal 2.30923 1.96281 0.067794 3.3179 1.3203 1.9976

Total states 43.14769 36.073550 16.42963 64.0452 35.3753 30.9951

Union territories

0.040760 0.007132 0.023360 0.0051 0.0008 0.0043

GRAND TOTAL

43.188450 36.080682 16.45272 64.05.0 35.3761 30.9994

The total groundwater reserves in the state are estimated to be 3.52

Mha-m out of which the present exploitation is 1.01 million ha meters

through dug wells and tube wells (Table 4.1). This leaves a balance of

2.51 Mha-m of exploitable groundwater potential, which can bring at

least 2 million ha under assured irrigation supplies to availability of

power for lifting of groundwater.

Source: CGWB, Ministry of Water Resources, GOI, Faridabad

(2000)

       The district wise groundwater potential estimated by Rao (1987) is

shown in Table   4.2. The maximum groundwater potential available is

in Nellore district and lowest in  Rangareddy district. With regard to net

draft of water, the Niazamabad district ranks first with 44.4% followed

by Karimnagar (42.9%) and Chittoor district (41.7%).

. Districtwise groundwater potential in Andhra Pradesh

District Groundwater potential (million ha meters)

 Total Utilizable

Actual utilization

  M.ha.m Per cent

for

Irrigation

1.Nellore 0.30 0.23 0.08 34.8

2.Guntur 0.28 0.22 0.02 9.1

3.West Godavari 0.23 0.18 0.05 27.7

4.East Godavari 0.21 0.16 0.02 12.5

5.Nalgonda 0.20 0.15 0.05 33.3

6.Khamman 0.19 0.14 0.02 14.3

7.Karimnagar 0.18 0.14 0.06 42.9

8.Prakasam 0.18 0.14 0.02 14.3

9.Warangal 0.17 0.13 0.05 38.5

10.Chittoor 0.16 0.12 0.05 41.7

11.Mahaboobnagar 0.15 0.11 0.04 36.4

12.Adilabad 0.14 0.10 0.02 20.0

13.Srikakulam 0.13 0.10 0.02 20.0

14.Medak 0.13 0.10 0.03 30.0

15.Nizamabad 0.12 0.09 0.04 44.4

16.Krishna 0.12 0.09 0.02 22.2

17.Kurnool 0.12 0.09 0.02 22.2

18.Anantapur 0.12 0.10 0.04 40.0

19.Vizianagaram 0.11 0.09 0.01 11.1

20.Cuddapah 0.11 0.08 0.03 37.5

21.Vishakapatnam 0.09 0.11 0.02 22.2

22.Rangareddy 0.07 0.06 0.02 33.3

Total 3.53 2.71 0.73

 Groundwater development scenario

Over the past five decades, Government policies of subsidizing

credit and rural energy supplies, liberal funding from Institutional

Finance  Agencies improvement in availability of electric power and

diesel, good quality seeds, fertilizers etc., have encouraged rapid

development of groundwater resources. Further during periods of

droughts, additional dependence is laid on this resource in view of

dwindling storage levels in surface reservoirs. 

Growth of groundwater abstraction structures

and irrigation Potential

Year Groundwater abstraction

Structures (million)

March,1951

3.865

March,1980

9.951

March, 1985

12.147

March, 1990

14.224

March, 1992

15.566

March,1997

17.334

Source: CGWB, GOI, Faridabad (2000)

 Over exploitation of groundwater 

In many arid and hard rock areas, overdraft and associated

quality problems are increasingly emerging. In 231 blocks (out of

total 4272) in various states in the country, besides 6 Mandals in

and12 Taluqs in Gujarat, situation of overdraft exists, i.e., the stage of

groundwater development has exceeded the annual replenishable

resource. In addition, in 107 blocks all over the country besides 24

Mandals in Andhra Pradesh 14 Taluqs in Gujarat and 34 watersheds

in Maharashtra, the stage of groundwater development has exceeded

85% of the annual replenishable resource.

The over draft of groundwater has resulted in:

• Failure of shallow wells,

• Shortage of water supplies

• Deepening of wells

• Increased pumping lights and pumping  costs

• Increased energy requirements

• Sea water ingress in coastal areas

• Increased inland salinity in groundwater

• Land subsidence due to compression of the aquifers

       Although groundwater is a renewable resource, it in not

inexhaustible. If groundwater supplies are to be maintained

perennially, the recharge must balance discharge. However, all that

recharged is not necessarily recoverable. The groundwater withdrawal

must be limited to safe yield, which is defined as the amount of water

that can be withdrawn annually from a groundwater basin without

producing an undesired result. While the permissive sustained yield

is the maximum rate at which water can be economically and legally

withdrawn perennially from a specified source, without bringing

about some undesired result. It is always less than natural recharge

and in limited by physical or other constraints.

 Overdraft (or over development) of aquifers occurs if

groundwater extraction exceeds the sustained yield. Perennial

pumping more than natural drainage may lead to decline in water

levels without any indication of water levels stabilizing, diminishing

yields and sometimes deterioration in water quality. The areas which

suffer from non- availability of groundwater due to perennial over

draft are known as dark areas. For example, widespread declines

have been reported from several places in India viz., Mehasana and

Ahmedabad in Gujarat, Rangareddy and Chittoor in Andhra Pradesh

and Coimbatore in Tamilnadu State. Many water supply wells in

Ahmedabad and Rangareddy have ceased functioning due to

persistent decline in water levels to the extent of nearly 30-300m.

 Overdraft may be reduced or controlled by changing over to less

water consuming crops, industrial processed etc., providing alternate

sources of supplies and most importantly by artificial recharge.

Administrative and legislative measures to discourage / prohibit

further exploitation become indispensable before critical overdraft is

reached.

Artificial recharge of groundwater

Artificial recharge may be defined as the process by which

infiltration of surface water into groundwater systems in increased by

altering natural conditions of replenishment. Artificial recharge

implies diverting of excess surface water resources (which otherwise

would go as runoff and unexploited) to the needs areas and provide

for infiltration into the groundwater zones. In the context of man’s

ever increasing demands on water resources, artificial recharge of

groundwater is gaining importance as one of the strategies of water

management. Several methods of artificial recharge are in vogue, the

choice being dictated by local conditions:

• Spreading methods

• Recharge through pits

• Recharge by irrigation and agricultural practices

• Percolation thanks

• Recharge through well

• Other methods of artificial recharge include, high blasting

of rocks to cause intensive fracture system in the near

impervious zones, into water could be disposed of by

infiltration and deep percolation.