Variability of Rainfall, Temperature and Potential Evapotranspiration at Annual Time Scale Over Tapi to Tadri River Basin, India

Abstract

The change in the meteorological variables is one of the most important factors that affect crop water requirements, and subsequently, water allocation for food production in agriculture-based countries like India. Present study evaluates the application of statistical trend detection tests and examines the magnitude slope of trends in climatic variables viz., rainfall, potential evapotranspiration (PET) and temperature over the west-flowing rivers in the Tapi to Tadri basin, India. In the present study, high-resolution daily gridded rainfall dataset of India Meteorological Department (IMD) at 0.25° × 0.25° resolution, while the PET and temperature data of Climate Research Unit (CRU) at 0.5° × 0.5° resolution have been analyzed for period of 116 years (1901–2016) at annual scale. The trends in aforesaid climate variables have been detected using nonparametric Mann–Kendall (MK) and Modified Mann–Kendall (MMK) tests, and the slope of trend magnitude is computed from Sen’s Slope (SS) test. The results indicated increasing trend in annual rainfall across 61% grids, while decreasing across 37% grids and no trends were observed at remaining grids out of 119 grids. Further, increasing trend in potential evapotranspiration, maximum, mean and minimum temperatures were observed at all the 40 grids. Thus, increase in temperature was greatly responsible for increasing trends in potential evapotranspiration across the study region. The outcomes of the present study provide insight of the climate variability and interaction among the meteorological variables across the Tapi to Tadri basin for the study period.