Impact Assessment of Water Harvesting Structures in Micro-Watersheds of Nira River Basin, Maharashtra, India

Artificial recharge is highly recommended in declining groundwater level trends as well as partially replenished aquifers. Moreover, the quantification of the recharge to aquifers due to such measures is important in water resource budgeting, development and planning. With this objective nine locations representing varied geomorphology were selected and the groundwater levels from the dug well in the proximity of water harvesting structures were monitored. The plot of monthly groundwater levels versus rainfall depicts that in the month of July high rainfall occurred but the groundwater levels raised in August due to delayed recharge process. The water level data also indicate the availability of water column of about 5m to 6m in most of the wells till the end of February, 2020. Water Harvesting structures overlaid on the Recharge Potential Zone map represent excellent (13.1%), very good (12.3%), good (23.3%), moderate (25.2) and poor (26.1) zones. The computation of artificial recharge from these structures depict that the structures having high storage capacity with a greater number of fillings have higher recharge. Also, the geophysical resistivity surveys were conducted to understand the degree of saturation at each location up to 50m, 100m and 150m distances from the structure. After integrating all datasets, it has been found that the structure at Shivajinagar has highest recharge followed by Pisalwadi, Kanheri, Zagalwadi 2, Kavathe, Ansur, Bholi, Limbachidwadi, Zagalwadi 1 and Kesurdi. Thus, the study concludes that the impact of water harvesting structures varies according to topography, land slope, geomorphology, size of catchment and lithology.