An integration of gauge, satellite and reanalysis precipitation datasets for the largest river basin of the Tibetan Plateau

Abstract

Abstract. As the largest river basin of the Tibetan Plateau, the Upper Brahmaputra River Basin (also called “Yarlung Zangbo” in Chinese) has profound impacts on the water security of local and downstream inhabitants. Precipitation in the basin is mainly controlled by the Indian Summer Monsoon and Westerly, and is the key to understand the water resources available in the basin; however, due to sparse observational data constrained by a harsh environment and complex topography, there remains a lack of reliable information on basin-wide precipitation (there are only nine national meteorological stations with continuous observations). To improve the accuracy of basin-wide precipitation data, we integrate various gauge, satellite and reanalysis precipitation datasets, including GLDAS, ITP-Forcing, MERRA2, TRMM and CMA datasets, to develop a new precipitation product for the 1981–2016 period over the Upper Brahmaputra River Basin, at 3-hour and 5-km resolution. The new product has been rigorously validated at different temporal scales (e.g. extreme events, daily to monthly variability, and long-term trends) and spatial scales (point- and basin-scale) with gauge precipitation observations, showing much improved accuracies compared to previous products. An improved hydrological simulation has been achieved (low relative bias: −5.94 %; highest NSE: 0.643) with the new precipitation inputs, showing reliability and potential for multi-disciplinary studies. This new precipitation product is openly accessible at https://doi.org/10.5281/zenodo.3711155 (Wang et al., 2020) and, additionally at the National Tibetan Plateau Data Center (https://data.tpdc.ac.cn, login required).

The extraordinary Namche Barwa sediment factory in the Eastern Himalayan Syntaxis

“…200,000 km 2 of the Tibetan Plateau. The annual precipitation remained constant as 700–900 mm in the Yarlung and Parlung gorges from 1981 to 2016 (Figure 8a), much lower than along the Himalayan topographic front in India (1500–4000 mm; Khatiwada & Curtis, 2021; Wang et al, 2020b), and channel steepness decreases from k sn > 800 in the Yarlung and Parlung gorges to k sn < 400 in the Siang River downstream (Figure 7). The lack of correlation between sediment yield from different catchments and average precipitation in the NBS ( R 2 = 0.26, p > .05) (Figure 9c) indicates that the spatial distribution of precipitation is decoupled from sediment yield and erosion rates.…”