Moisture Supply From the Western Ghats Forests to Water Deficit East Coast of India

The mountainous western coast of India, known as the Western Ghats, is considered to be a biodiversity hot spot, but it is under a constant threat due to human activities. The region is characterized by high orographic monsoon precipitation resulting in dense vegetation cover. Feedback of such a dense vegetation on the southwest monsoon rainfall is not yet explored. Here we perform regional climate simulations with the Weather Research and Forecasting model and find that evapotranspiration from the vegetation of Western Ghats contributes 25-40% of the southwest monsoon rainfall over the water-deficit state of Tamil Nadu. This contribution reaches 50% during deficit monsoon years or dry spells within a season. Our findings suggest that recent deforestation in this area will affect not only the biodiversity of the region but also the water availability over Peninsular India, which is already impacted by water scarcity. Plain Language Summary Forests over the Western Ghats (WG) region at the west coast of India are suffering from severe deforestation. We find that the vegetation over the WG region contributes moisture to the precipitation of the water-deficit state of Tamil Nadu and it reaches as high as 40% in many of the regions. Tamil Nadu is at present is under severe water crisis due to interstate water sharing and related controversies. We emphasize the urgent need of enforcing strict laws to stop the deforestation of WG not only to retain bio-diversity but also to maintain the water cycle over these semiarid parts of Peninsular India.