Dynamics of Vegetation Response to Seasonal Rainfall in the Gomati River Basin (India) using Earth Observation Data Sets

Abstract

Present study evaluates the vegetation responses towards the rainfall variability in the Gomati basin during 1901-2015. To accomplish the same, high resolution observed daily gridded rainfall data from India Meteorological Department (IMD) was analysed using non-parametric trend test. The long-term rainfall showed significant decreasing trend (=0.05) which varied from -0.96 to -4.89 per year. Identified trends in rainfall were then evaluated in tandem with the basin-wide changes in the vegetation signatures during the recent extreme years (two pairs of dry and wet years). Each pair of extreme years was assessed for its seasonal Normalised Difference Vegetation Index (NDVI) related to the seasonal rainfall variations with special emphasis to rice and wheat yields (major crops). Contribution of spatio-temporal occurrences of rainy days with that of the heavy rainfall events was also analysed. The findings suggest that the prevalent basin-wide longterm rainfall deficiency intensified during the extreme dry years e.g. 2002 and 2009 and impacted the health of vegetation in the basin. Vegetation of the basin was found closely related with rainfall variability; regular and well distributed occurrences of rainy days benefited the basin's vegetation as well as the yields of rice and wheat crops.