Balancing watershed and local scale impacts of rain water harvesting in India-A review

Agricultural production in India has become increasingly reliant on groundwater and this has resulted in depletion of groundwater resources. Rainwater harvesting (RWH) for groundwater recharge is seen as one of the solutions to solve the groundwater problem. This is reflected in an increase in watershed development programs, in which RWH is an important structural component. Understanding the net effect of these development programs is crucial to ensure that net effect on groundwater is positive both locally and within a watershed. Hence, this review focuses on the hydrological impacts of RWH for recharge at the local (individual structure) and watershed scale in rural areas. Surprisingly little field evidence of the stated positive impacts at the local scale is available, and there are several potential negative impacts at the watershed scale. The watershed scale is underrepresented in the field studies and is mainly approached through modelling. Modelling is seen as a possible tool to extend limited field data and scenario studies can be used to examine potential impacts. However, many past modelling studies examining RWH have either had limited focus or have been based on insufficient data. Development of new modelling tools is needed in combination with increased field data collection. Increased use of remote sensing and advanced statistical techniques are suggested as possible new opportunities. In addition, some evaluation criteria are proposed to assess the local and watershed scale hydrological, and other, impacts of RWH as part of watershed development. (C) 2012 Elsevier B.V. All rights reserved.