surface and subsurface outflows are minimized, causing reduction in peak runoff;
when conjunctive use is integrated with artificial recharge the need for lining canals is reduced, as seepage from canals feeds groundwater;
conjunctive use allows the utilization of saline or brackish ground – or surface – water resources, either by mixing them with freshwater, or by using alternate water resources for irrigation events.
However, there are some constraints that may impair the efficiency of conjunctive use projects, such as:
increased energy consumption for pumping from wells and for coping with reduction in pump efficiency, due to large fluctuations of water levels;
administrative difficulties in defining acceptable and equitable groundwater rates, when surface water is available.
3. Research Thrust and Development
Research needs to be focused more effectively than in the past on planning and management problems of conjunctive use of surface and groundwater. This is the main way to provide planners and decision makers with suitable and well-tested technologies for targeted measures designed to enhance conjunctive use efficiency, while protecting the environment. The lack of research, application of research findings and access to new and advanced technology, is seen as one of the main reasons for the problems plaguing the sector: low efficiency, environmental degradation, high costs and lack of beneficiary responsiveness. Successful research thrust on sustainable integrated water resource management should include the following actions: