Abstract
Glacial changes have great effects on regional water security because they are an important component of glacierized basin runoff. However, these impacts have not yet been integrated and evaluated in the arid/semiarid inland river basins of western China. Based on the degree-day glacier model, glacier changes and their hydrologic effects were studied in 12 subbasins in the Shiyang River basin (SYRB), Heihe River basin (HHRB) and Shule River basin (SLRB). The results showed that the glacier area of each subbasin decreased by 16.7–61.7% from 1965 to 2020. By the end of this century, the glacier areas in the three basins will be reduced by 64.4%, 72.0% and 83.4% under the three climate scenarios, and subbasin glaciers will disappear completely after the 2070s even under RCP2.6. Glacial runoff in all subbasins showed a decreasing–increasing–decreasing trend, with peak runoff experienced in 11 subbasins during 1965~2020. The contribution of glacial meltwater to total runoff in the basin ranged from 1.3% to 46.8% in the past, and it will decrease in the future due to increasing precipitation and decreasing glacial meltwater. However, the scale differences in glacier runoff are significant when aggregated over the region/basin/subbasin. This suggests that the results of large-scale generalization may be misleading for subbasin glacier water resource evaluations. Therefore, the hydrological effects of glaciers should be studied more in subbasins to provide an accurate reference for practical water resource management.
Highlights
Bliss and others assessed the global-scale response of glacier runoff to climate change in 18 glacierized regions, and the results indicated that most regions showed decreasing runoff trends, only three regions showed steady increases and two regions showed increases followed by decreases in the 21st century [21]
The historical and future mean temperatures on glaciers of three inland river basins generally decreased from east to west and were affected by elevation; the warmest and coldest subbasins were Dongda and Hongshui, respectively
Assessment of the impact of glacial change runoff on watershed water resources can help water managers respond to potential water crises under climate change
Summary
Glacial shrinkage under global warming is releasing large amounts of freshwater resources from global glaciers, which has significant impacts on the regional and global hydrological cycles [1,2,3,4,5]. Glacier mass loss contributed 27 ± 22 mm to the global sea level rise from 1961 to 2016 [6], and this flow of freshwater potentially affected the current ocean system [7,8]. On regional and local scales, glaciers are significant contributors to seasonal river flows, serving as frozen reservoirs of water that supplement runoff during warm and dry periods of low river flows [3,4,9,10,11,12]. In High Mountain Asia, glacial meltwater is critical to the water security of 800 million downstream residents [13,14,15]
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