Freshwater from the mountains is vital for the region’s economy and for sustaining the livelihoods of a fast-growing population. The largest Asian rivers (e.g., Yangtze, Mekong, Ganges, Indus and Brahmaputra) originate from the surrounding glacierized and snow-capped mountain ranges, which act as “water towers” through transient storage and release of water previously stored as snow or ice. The most vulnerable water towers on Earth are located in High Mountain Asia (HMA) and are highly sensitive to climate change. High topography and contrasted climate are the main geographical features of HMA, an area under the influence of two major circulation systems, the Mid-latitude westerlies and the South Asian monsoon. Large orogenic belts such as the Himalayas control precipitation distribution as a result of orographic effects due to their prominent relief. The contribution of glaciers to runoff varies regionally, from 19% in the Dudh Koshi catchment, which is a major tributary of the Ganges (east), up to 81% in the Hunza catchment that drains into the Indus (west). The complexity of the land surface atmosphere interactions arising from these circulation systems hampers our capacity to understand and to simulate correctly the meteorological variables. In particular, high mountain (e.g. > 4 000 m a.s.l.) precipitation patterns are poorly understood. Indeed, gridded precipitation datasets based on remote sensing or interpolated from rain gauges have a too coarse resolution to reproduce the local variability of precipitation measured at ground stations, in particular where strong topographic gradients are observed. This leads to large uncertainty in hydrological modelling and quantification of natural water availability in one of the most densely populated areas of the world. In such context, the main objective of this IJL is to assess the spatio-temporal variability of high-elevation precipitation in the Himalayas, with a focus on one region influenced by the Asian monsoon (the Everest region, Nepal), in order to better quantify the impacts of climate and glacier changes on water resources at regional scale.

Updated on 20 January 2023