Abstract
Precipitation plays vital roles in the global water cycle, knowledge of the spatial and temporal variation of the precipitation is essential to understanding extreme environmental phenomena such as floods, landslides, and drought. In this paper, the integrated characteristics of precipitation during 1980–2016 over Nepal along with the seasonal elevation dependency of precipitation were examined for three different regions over the country using Multi-Source Weighted-Ensemble Precipitation (MSWEP) product. The spatial distribution of mean annual precipitation varies significantly with the highest (lowest) precipitation of ~5500 (~100) mm/year in the Arun valley (Manang and Mustang). The precipitation regime of the country is determined by the contribution of the monthly precipitation amount with distinct spatial gradients between the eastern and the western sides during pre-monsoon, post-monsoon, and winter seasons. On the contrary, the spatial distribution of monsoon precipitation tends to more heterogeneous with visible differences between the lowland, midland, and highlands as similar to the annual one. Further, elevation dependency of seasonal precipitation revealed that the winter and post-monsoon precipitation distribution in western and central are very similar, whereas post-monsoon precipitation was found slightly higher than winter season in the eastern region. The highest precipitation areas in eastern and central region are located between 2000-2500 m, which is between 500 and 1000 m in the western region of the country. Overall, the pre-monsoon, summer monsoon and annual precipitation increases gradually with elevation upto 2500 m and then decreases with increasing elevation, whereas winter and post-monsoon precipitation are almost identical to each elevation interval of 500 m.
Highlights
Complex climate, coupled with topographic variability makes regional water resource management challenging, especially in high-altitude areas (Viviroli and Weingartner, 2004)
Elevation dependency of seasonal precipitation revealed that the winter and post-monsoon precipitation distribution in western and central are very similar, whereas post-monsoon precipitation was found slightly higher than winter season in the eastern region
It is notable that Multi-Source WeightedEnsemble Precipitation (MSWEP) precipitation product captured the rain shadow areas in the high-elevation areas of the central region
Summary
Complex climate, coupled with topographic variability makes regional water resource management challenging, especially in high-altitude areas (Viviroli and Weingartner, 2004). Rain gauge-based observations from the Department of Hydrology and Meteorology (DHM), Government of Nepal provide the ground-based measurements of precipitation in Nepal, and these stations are non-uniformly distributed across the country (concentrated in the southern lowlands and scanty in high mountain areas) (Diodato et al, 2010; Barros and Lang, 2003). Such paucity of accurate observations mounts significant challenges to hydro-meteorological studies and comprehensive management of precipitation induced disaster. Accurate modeling and prediction of the precipitation variability over the country are crucial for forecasting and for the management of water resources, which is especially important for the mountainous country(Anjum et al, 2019; Bhardwaj et al, 2017; Burton et al, 2018)
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