Modeling of Mass Balance Variability and Its Impact on Water Discharge from the Urumqi Glacier No. 1 Catchment, Tian Shan, China

Kira Thiel,Huilin Li,Zhongqin Li,Anselm Arndt,Christoph Schneider,Puyu Wang

doi:10.3390/w12123297

Abstract

Originating in the Tian Shan mountains, Urumqi River plays a key role in terms of water supply to downstream areas. In its headwaters, Urumqi Glacier No. 1 (UG1) is the largest glacier contributing to water discharge. Assessing its response to the changing climatic conditions in the area is of major importance to quantify future water availability. We here apply COSIPY, a COupled Snowpack and Ice surface energy and mass balance model in PYthon, to UG1, implementing a new albedo parameterization which integrates site-specific bare-ice albedo values on a pixel-by-pixel basis observed by remote sensing. We assess model performance threefold: quantitatively based on long-term measurement data of (1) surface mass balance (SMB) and (2) water discharge as well as qualitatively (3) comparing simulated snow line altitudes to such imated on the basis of time-lapse photography. Comparison of the modeled SMB with annually-averaged data from ablation stakes reveals that COSIPY including the new albedo parameterization accounts for 57.6% of the variance observed in the measurements. The original albedo parameterization performs only slightly inferior (57.1%). Glacier-wide comparison between modeled and glaciological SMB shows high agreement. In terms of discharge prediction, COSIPY reproduces onset and duration of the discharge season well. Estimated discharge from the whole catchment shows shortcomings in exactly matching the measured times series, but interannual variability is captured.

Highlights

Glaciers are an important part of the global and local water budgets
surface mass balance (SMB) with annually-averaged data from ablation stakes reveals that COSIPY including the new albedo parameterization accounts for 57.6% of the variance observed in the measurements
Maximum annual SMB is modeled by COSIPY for 2014, when annual SMB is

Summary

Introduction

Glaciers are an important part of the global and local water budgets. They are highly sensitive especially to air temperature and precipitation, both of which increasingly underlie long-term changes due to climate change. With regard to local water supply, assessing glacier development becomes increasingly important [1,2,3,4]. Glacier-runoff responses to climate change are manifold depending on general setting and climate both concerning the expected long-term overall annual changes and their seasonal patterns (e.g., [5,6,7,8]). Surrounded by the Taklimakan Desert, the Gurbantunggut Desert and the Gobi Desert, Urumqi River constitutes an important water resource, to Urumqi, the capital of the province [9].

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