Assessing the impact of climate change on flood inundation and agriculture in the Himalayan Mountainous Region of Bhutan

Study region: The Punatshangchu River Basin and the Wangchu River Basin in Bhutan. Study focus: Mountain regions are more sensitive to changes in environment and climate. Changes in intensity and magnitude of floods due to climate change will have devastating impacts, including on agriculture, a main source of people's livelihoods and a primary economic driver of many countries. We analyzed impacts of climate change on flood inundation and flood damage to agriculture in the Himalayan Mountains of Bhutan. Projected rainfall from general circulation models was used to simulate flood characteristics from the rainfall-runoff-inundation model, to calculate the agriculture damage loss to rice crops. New hydrological insights for the region: The results show an increase of approximately 60% in magnitude in annual rainfall towards the end of the century, with extreme rainfall events greater than 32% for the river basins. The increase in changes in rainfall will result in an increase in inundation of almost 60% and 90% for the Punatshangchu River Basin and the Wangchu River Basin, respectively. The inundation depth and volume could increase up to 60%. With the increase in inundation characteristics, the damage to agricultural areas is expected to increase by 2 to 6 times, and the damage loss value increase from 2 to 38 times in the river basins.