Rainfall over the Himalayan foot-hill region: Present and future

Abstract

Uttarakhand, one of the Himalayan foot-hill states of India, covers an area of 51,125 km². This region is enriched with bio-diversity and is one of the highly potential regions in the Central Himalayas for agro-climate, hydro power generation, food-processing, tourism, etc. Present study investigates the spatio-temporal rainfall distribution over the state during Indian summer monsoon period. Observational and modelled (under different Representative Concentration Pathways (RCPs) at radiative forcing 2.6, 4.5 and 8.5 W/m²) rainfall distribution is studied to assess the present and future trends. Study uses standard observational rainfall estimates from APHRODITE, Tropical Rainfall Measuring Mission (TRMM 3B42) and India Meteorological Department (IMD) gridded rainfall datasets and inter-compare these products in order to find out orographic responses during the monsoon months and elevation dependent mean rainfall pattern changes. It is found that rainfall pattern breaks near 3100 m elevation. Comparative analysis reflects that with respect to IMD, TRMM 3B42 rainfall underestimates more than 3 mm/day rainfall whereas, APHRODITE overestimates rainfall below 4.5 mm/day. Future trends in modelled monsoon rainfall are examined and mixed results are found and discussed with possible explanation.