Influence of reservoir on propagation from meteorological to hydrological drought for Tapi river basin

Meteorological drought generally gets propagated into agricultural and hydrological drought. Hydrological drought is characterized by reduced streamflow in the river regime. Due to the interconnection between different drought types, it is important to analyze the drought propagation time. Propagation from meteorological to hydrological drought is of prime concern, as hydrological drought is having immediate consequences on industry, agriculture, and the water supply system. In the present study propagation time from meteorological to hydrological drought was studied using the spearman rank correlation coefficient for the Tapi river basin of India having semi-arid climatic conditions.  Spearman rank correlation was calculated between lagged values of the standardized precipitation index (SPI-1,2,3,4,5,6,7,8,9,10,11,12), and monthly standardized streamflow index (SSI-1). Drought propagation under the influence of the Ukai reservoir was analyzed for Sarangkheda and Ghala gauging stations. Sarangkheda station is in the upstream of the Ukai reservoir whereas, Ghala station is in the downstream. Results indicated that there is a clear influence of reservoir on propagation time from meteorological to hydrological drought. The highest correlation for the Sarangkheda station was observed for SPI-5 and SSI-1, whereas, for the Ghala station, it is for SPI-12 and SSI-1. Propagation time has significantly increased for reservoir-influenced gauging station as compared to gauging station in the natural catchment. The present study is important as information on propagation time under the influence of a reservoir can be useful to the water resource manager, stakeholders, and policymakers for doing the required preparation and taking necessary measures.