Rationalization of Altitudinal Precipitation Profiles in a Data-Scarce Glacierized Watershed Simulation in the Karakoram

Abstract

Due to the scarcity of field observations and geodetic measurements in catchments in the Karakoram Mountains in Western China, obtaining precipitation data for the high mountains involves large uncertainties and difficulties. In this study, we used a functional relationship between the annual glacier accumulation and summer temperature at the equilibrium line altitude (ELA) to derive precipitation lapse rates (PLAPSs) in a data-scarce watershed. These data were used in a modified Soil and Water Assessment Tool (SWAT) model with a glacier module to simulate glacio-hydrological processes in the Yarkant River basin in the Karakoram. The PLAPS based on the widely-used grid datasets considerably underestimated precipitation, yielding an unreasonable watershed water balance and inaccurate glacier changes. However, the ELA-based PLAPS improved the simulation significantly. In the Yarkant River basin, the annual precipitation reached a peak of 800-1000 mm at approximately 5300 m a.s.l. The model simulations indicated that the contributions of glacier melt and ice melt to total runoff were 52% and 31%, respectively. Moreover, a significant precipitation increase and a non-significant temperature increase during the melt season may be the major reasons for the decreased ice melt and slower glacier shrinkage on the northern slope of the Karakoram during the period of 1968-2007.

Multi-scale temporal variability in meltwater contributions in a tropical glacierized watershed

“…The short data records from Reschreiter were primarily used together with Boca Toma data to determine a lapse rate for precipitation. Precipitation in mountainous watersheds typically exhibits piecewise linear relationships with elevation, with positive (negative) lapse rates below (above) the elevation of maximum precipitation (Wang et al, 2016). We calculated a negative lapse between the two weather stations, which we applied over the entire watershed with the assumption that the elevation of maximum precipitation lies below the watershed.…”

“…Each stake included a temperature sensor, along with a look-down ultrasonic sensor for measuring changes in distance to the ice surface to estimate glacier mass loss in clean ice. The stakes were deployed using the open-source Arduino-compatible ALog data logger (BottleLogger v1.4.0, an intermediate model between v1.0.0, Wickert, 2014, andv2.2.0, Wickert et al, 2018). All sensors were mounted at the top of 3 m long PVC tubes, which were inserted into holes drilled to about 2.5 m depth.…”

Generation of High Mountain Precipitation and Temperature Data for a Quantitative Assessment of Flow Regime in the Upper Yarkant Basin in the Karakoram

“…In order to construct reliable meteorological data in the UYB, especially for high altitudes, lapse rates for precipitation and temperature are used to generate precipitation and temperature data across the basin. The lapse rates in previous hydrometeorological studies in the UYB were mostly derived from stations at low altitudes or other indirect factors such as glacier mass accumulations (Liu et al, ; Wang et al, ), which lead to some uncertainties in derived precipitation or temperature data and thus in hydrological model simulations.…”

“…The climate of the Karakoram ranges is primarily influenced by midlatitude westerlies and the summer southeastern monsoon from the Indian Ocean (Moelg et al, ). For precipitation, about 67% of annual precipitation occurs in the months of May to September, and less than 33% falls in other months (Wang et al, ). Temperature has a large seasonal variation with the highest and lowest records in summer and winter, respectively.…”

Reviving the Aral Sea: A Hydro‐Eco‐Social Perspective

“…Both APHRODITE and PGMFD datasets, spanning from 1951 to 2015, have a spatial resolution of 0.25° × 0.25°. To account for spatial heterogeneity in precipitation and temperature across mountainous regions, monthly lapse rates were calculated and incorporated, following the methodology described in a previous study (Wang, Sun, et al., 2016).…”