Variations of glacier hydrological regulation in the north- and south-facing slopes of Tianshan Mountains, China: Past and future

Abstract

Study region: The upstream reaches of Manas River Basin (UMNS), and Muzati River Basin (UMZT) Study focus: Glaciers, as solid reservoirs, substantially regulate runoff abundance and depletion through peak shaving and valley filling. The regulations of glaciers in hydrological cycles are crucial to the arid regions. We aim to quantify the dynamics of the glaciers’ hydrological regulating function in the UMNS and UMZT from 1971 to 2100 using a glacier hydrological regulation index (GlacierR). New hydrological insights for the region: Our results indicate that the glacier runoff in both basins showed a decreasing trend in the past four decades and will continue decreasing in the future under three shared socioeconomic pathways (SSPs): SSP1–2.6, SSP2–4.5, and SSP5–8.5. The UMZT has a stronger regulating function of glacial runoff than the UMNS. In contrast, the tipping point of the glaciers’ hydrological regulating function in the UMNS occurred ten years earlier than in the UMZT. Under the three SSPs, the glaciers’ hydrological regulation function on the north- and south-facing slopes of the Tianshan Mountains will show a weakening trend. The weakness trend is more notable in UMZT, where the glaciers’ hydrological regulation function will decrease by 66.9 % between 2061 and 2100 under SSP1–2.6. Thus, it sets alarm bells for the rational use of water resources in glacier-covered arid regions.

Keywords

• Glacier runoff
• Glaciers’ hydrological regulation
• CMIP6
• North- and south-facing slopes of Tianshan