Abstract
Abstract. This paper provides a new representation of the effect of altitude on precipitation that represents spatial and temporal variability in precipitation in the Everest region. Exclusive observation data are used to infer a piecewise linear function for the relation between altitude and precipitation and significant seasonal variations are highlighted. An original ensemble approach is applied to provide non-deterministic water budgets for middle and high-mountain catchments. Physical processes at the soil–atmosphere interface are represented through the Interactions Soil–Biosphere–Atmosphere (ISBA) surface scheme. Uncertainties associated with the model parametrization are limited by the integration of in situ measurements of soils and vegetation properties. Uncertainties associated with the representation of the orographic effect are shown to account for up to 16 % of annual total precipitation. Annual evapotranspiration is shown to represent 26 % ± 1 % of annual total precipitation for the mid-altitude catchment and 34% ± 3 % for the high-altitude catchment. Snowfall contribution is shown to be neglectable for the mid-altitude catchment, and it represents up to 44 % ± 8 % of total precipitation for the high-altitude catchment. These simulations on the local scale enhance current knowledge of the spatial variability in hydroclimatic processes in high- and mid-altitude mountain environments.
Highlights
The central part of the Hindu Kush Himalaya region presents tremendous heterogeneity, in particular in terms of topography and climatology
The main objective of this paper is to provide a representation of the effect of altitude on precipitation that represents spatial and temporal variability in precipitation in the Everest region
A weighted inverse distance method coupled with a multiplicative altitudinal factor was applied to spatially extrapolate measured precipitation to produce precipitation fields over the Dudh Kosi Basin
Summary
The central part of the Hindu Kush Himalaya region presents tremendous heterogeneity, in particular in terms of topography and climatology. Two main climatic processes on the synoptic scale are distinguished in the central Himalayas (Barros et al, 2000; Kansakar et al, 2004). Dhar and Rakhecha (1981) and Bookhagen and Burbank (2010) assessed that about 80 % of annual precipitation over the central Himalayas occurs between June and September. The second main climatic process is a west flux that gets stuck in appropriately oriented valleys and occurs between January and March. Regarding high altitudes (> 3000 m), this winter precipitation can occur exclusively in solid form and can account for up to 40 % of annual precipitation (Lang and Barros, 2004) with considerable spatial and temporal variation
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