Variation in Hydrological Components of Reservoirs as a Response to El Niño Southern Oscillation

Abstract

El Niño Southern Oscillation (ENSO) is an irregular periodic variation of atmospheric pressure and sea surface temperatures over the tropical eastern Pacific Ocean, affecting climate in most of the tropics and subtropics, which in turn affects water resource availability and crop productivity. Reservoirs have a vital role in management of water resources in regions with multiple cropping patterns. The present study analyzed the impacts of ENSO on reservoirs and its hydrologic components in the Venna river basin of central India. In the present study, the impact of ENSO on water availability in reservoirs was analyzed using spatial analysis of satellite-derived water-spread area (the spatial distribution of water in the reservoir) and its kappa statistics. The normalized difference vegetation index (NDVI) was used to estimate the area of vegetation in catchment and command areas. Analyses reveal that surplus and deficient water available in reservoirs and the area of vegetation in catchment and command areas harmonized with ENSO phases. Analysis of the variation in impacts of ENSO on reservoir-irrigated area (RIA) and groundwater-irrigated area (GWIA) revealed that average NDVI was higher in RIAs compared to GWIAs, and the difference is greater for La Niña and less for El Niño. The onset of greenness is delayed for RIAs as well as GWIAs during El Niño.