Induced groundwater recharge in the Ganges Basin

The Ganges basin in India has a serious problem of water availability. The basin area, which is only one twelfth that of the United States, has a population greater than the total U.S. population, and it is increasing at a rate of 2.5% per annum. About 77% of the population is engaged in agriculture which is totally dependent on irrigation, as almost 85% of rainfall takes places in 2–3 monsoon months. Surface storage possibility is extremely limited, but groundwater recharge appears feasible, since sedimentary alluvial formations extend to depths of thousands of meters. Three alternative schemes of groundwater recharge have been proposed. One involves pumping heavily along perennial rivers prior to monsoons so as to lower groundwaters to promote induced groundwater recharge. The second proposes a similar approach along nonperennial rivers. The third involves irrigation during monsoons with groundwater lowered adequately in the nonmonsoon period so that enough induced groundwater recharge takes place to provide adequate supplies for nonmonsoon months. A simulation‐optimization model has been developed to study the surface flow‐groundwater interaction and has been applied to study comparative cost effectiveness of the three alternate approaches. Sensitivity analysis has also been carried out. It is shown that the third scheme is the most attractive.