conjunctive use of water

CONJUNCTIVE USE OF WATER

The term “Conjunctive use “of water resource implies the

coordinated and harmonious development for increased

efficiency of water from different resources. Thus Conjunctive

use of water resource can be defined as “ the management of

multiple water resources in a coordinated operation such that, the

water yield of the system over a period of time exceeds, the sum

of yields of the individual components of the system, resulting

from in-coordinated operation”.

 It is not mutely providing groundwater supply and

distribution system as a back up for a surface water system or

vice  versa, rather it is a concept in which one system

complements and supplements the other to compensate for the

inadequacies of both “.

 It is integrated management of both surface and ground

water components in order to make best use of the complement

ary potential of each and to optimize the use of water resources.

 Objectives

1. Mitigating the effect of shortages in canal water

supply

2. Increasing the dependability of existing water

supply

3. Alleviating the problem of high water table and

salinity

4. Facilitating the use of high salinity ground water

5. Mitigating the damages due to drought

6. Increasing the efficiency of surface water system

 Systems of conjunctive use

Abrol et al. (1988) listed the following systems of conjunctive

use:

1. Canal water and ground water system

2. Rainfall and irrigation water system

3. Saline water and fresh water system

 Advantages

1. Use of ground water helps reduce peak demands for

irrigation, size of canals, and hence construction  costs

2. Supplemental supplies from groundwater ensure proper

irrigation scheduling raising multiple crops and early

sowing even if rainfall is delayed

3. Increased water resources ensure supply to tail end areas

of higher elevation.

4. Ground water exploitation lowers the water table and

reduces danger of water logging and consequent wastage

of water for leaching of soils

5. Surface and subsurface out flows are minimized causing

reduction in peak run off and flood discharge

6. Conjunctive use when integrated with an artificial

recharge project the need for lining of canals is reduced as

seepage from canals recharges ground water 

7.  During periods of peak water demand irrigation

requirement can be met by surface water sources, so power

saved can be diverted to other sectors 

8. Conjunctive use is an attractive benefit considering the

difficult political and environmental challenges facing

many surface water storage projects

 Constraints

1. Possibility of deterioration in ground-water quality due to 

influx of salts leached down from the soil which may be

quite marked as a result of recycling within cones of

depressions and / or upward and lateral migration of saline

water intro fresh water zones in response to pumping.

2. Increased power consumption to sustain pump age  from

wells. Possible dislocation of groundwater supplies due to

power failure in critical periods, and decrease in pump

efficiencies supplies due large fluctuations in water

levels.

3. Operation, supervision and control of conjunctive use and

artificial recharge projects are more complex

4. Administrative difficulties in evolving acceptable and

equitable water rates, providing motivation and incentives

to accept groundwater use when surface water is available

(Aquifer storage and Recovery (ASR) is a form of

conjunctive use where excess water is stored under

ground is a suitable aquifer later as needed).