Abstract
Under the influence of climate change, the hydrological processes of glaciers have undergone significant changes, a fact which is seriously affecting agricultural production in the downstream region of the Tianshan Mountains, China. In order to explore the intrinsic relationship between climate change and hydrological elements, we proposed an “evaluation-driving-prediction” system to study it. First, we constructed a glacier-enhanced soil and water assessment tool model (GE-SWAT) and used a two-stage calibration method to optimize the model parameters. Next, a scenario analysis was used to evaluate the driving factors of historical runoff changes. Finally, we projected future runoff changes using bias-corrected regional climate model (RCM) outputs. The results of the case study on the Jinghe River Basin in the Tianshan Mountains show that from 1963 to 2016, total runoff increased by 13.3%, 17.7% of which was due to increasing precipitation and 1.8% of which was negated by rising temperatures. The glacier runoff increased by 14.5%, mainly due to the rising temperatures. A 3.4% reduction in snowmelt was caused by a lower snowfall/precipitation ratio, which significantly reduced the snowfall from June to August. The RCM projection indicated that the warming and humidification phenomenon in the study area will continue at least through to the mid-21st century. A consistent increase in glacier runoff and total runoff is projected, but the contribution rate of the glacier runoff will have little to no change under the RCP4.5 and RCP8.5 emission scenarios. Our research demonstrates the simulation performance of the GE-SWAT model in a basin with moderate glacier cover. This method is shown to be efficient in quantifying the impact of climate change on glacier hydrological processes and predicting future streamflow changes, providing a good research reference for similar regions.
Highlights
Introduction distributed under the terms andAs the source catchment area of many rivers in Central Asia, the Tianshan Mountains incorporate 10,778 glaciers [1], supplying valuable freshwater resources to oasis agriculture and livestock downstream, and nurturing nearly 50 million people from Kazakhstan, Kyrgyzstan, and China [2]
We forecast the trend and quantity of future runoff using a model forced by the bias-corrected regional climate model (RCM) data under RCP4.5 and RCP8.5
The 0.5-degree gridded datasets were used as the model input for historical periods in this study, and the meteorological input data of different elevation zones were adjusted to make the physical meaning of the model clearer by setting the elevation zone, PLAPS, and temperature lapse rate (TLAPS)
Summary
As the source catchment area of many rivers in Central Asia, the Tianshan Mountains incorporate 10,778 glaciers (with an area of approximately 13,567 km2 ) [1], supplying valuable freshwater resources to oasis agriculture and livestock downstream, and nurturing nearly 50 million people from Kazakhstan, Kyrgyzstan, and China [2]. 2022, 14, 1314 warming characteristics of the climate in the Tianshan Mountains have been very obvious for more than half a century. In the past few decades, the peak value of the discharge hydrograph over the course of a year has shifted to an earlier time, the flood season runoff has increased, and the total runoff has increased [6]; it will eventually decrease, due to the reduction in glacier area [7], further exacerbating the instability of water resources and the contradiction between supply and demand. Due to the critical role of glaciers in downstream water supplies, systematic assessments of past, present, and future changes are required to develop imperative and efficient measures to adapt to these changes in climate
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