Dynamics of overland flow under changing cropping pattern: A spatial modeling approach in Penganga Sub-watershed

Abstract

A simulation study using SWAT hydrological model has been carried out to evaluate the impacts of changing cropping pattern and agricultural expansions on overland flow in Penganga Sub watershed, Maharashtra. Remote sensing data combined with ground-truthing and extrapolation of pixel signatures were done for generation of spatial crop inventory for the years 2011, 1999,1990 and1976. The crop inventory analysis showed a significant change in the cropping pattern over the decades. Less water intensive crops like Jowar, Tuarand Gram were heavily replaced by water intensive crops like Cotton and Wheat. Over 30% of the open scrubs were also converted for cultivation. These four different scenarios were modeled without hydrological structuresunder constant climatic conditions of 1975-76. The resultant simulated runoff showed higher peak discharges (∼2000 cumecs in July, ∼1500 cumecs in September) under the cover conditions of 1975. Under similar climatic conditions the consecutive scenarios showed gradual decline in runoff. The flow generatedunder the cover conditions of 2011 showed lowest and delayed peak discharges (∼1000 cumecs in July and ∼700 cumecs in September). The study showed that the shift in cropping pattern to water intensive crops reduced surface flow. This calls for appropriate crop combination for better utilization of available water.