Characterizing precipitation uncertainties in a high-altitudinal permafrost watershed of the Tibetan plateau based on regional water balance and hydrological model simulations

Abstract

Study regionthe source region of the Yangtze River (SRYR) Study focusPrecipitation uncertainties significantly impact water resource management, while the uncertainties of various precipitation products are not fully investigated due to the lack of observations, especially in high-altitudinal permafrost areas. In this study, we selected nine products representing three types of precipitation, including gauge-based, satellite-based and merged products, and conducted a comprehensive evaluation using regional water balance method and hydrological model simulations. New hydrological insights for the regionOur results indicate most precipitation products can replicate the observed precipitation decreasing trend with increasing elevation below 4500 m, but trends vary at higher elevations. The gauge-based precipitation products with bias correction outperform others, while most satellite-based products underestimate precipitation. The water-balance based evaluation shows a merged product (TPHiPr), and two gauge-based products perform best, followed by a satellite-based product (MSWEP). Process-based model simulations driven by selected precipitation products can reproduce daily runoff processes well in the entire SRYR (NSE = 0.68–0.86), but the performance degraded in the high-altitudinal Tuotuohe subbasin (NSE = 0.08–0.76). The runoff coefficients comparisons in these two regions also indicate the possible deficiencies of precipitation products in the high-altitudinal regions. Our results highlight the challenges of current precipitation products in characterizing the spatial and temporal precipitation changes in the high-altitudinal permafrost regions, and call for more accurate products in these areas.