Exploring future trends of precipitation and runoff in arid regions under different scenarios based on a bias-corrected CMIP6 model

Precipitation and runoff changes play a very important role in ecosystems and human well-being. Predicting its changes is critical for water resource management and coping with climate change. However, corresponding studies in arid regions are limited by lack of data and poor spatial distribution of meteorological stations. Therefore, this study identified the applicability of multi-source meteorological data in a typical arid region, the Shiyang River Basin, by comparing its variability with measured precipitation. Then, the best applicable precipitation product was selected to correct the data of CMIP6, and to predict the change of precipitation and runoff under the scenarios of SSP126/245/585 by 2100. The results showed that the CMADS dataset was more consistent with the measured data than TRMM and CFSR. Through Taylor diagram analysis and equidistant cumulative distribution functions matching (EDCDF) method bias correction, the GFDL-ESM4 model was more suitable for arid regions in terms of precipitation and temperature. During 2015-2100, the annual precipitation and average annual temperature under each scenario all showed an increasing trend. However, the monthly precipitation from May to October showed a decreasing trend, indicating an increase in precipitation during spring and winter, and a decrease during summer and autumn. The average temperature for all months from January to December showed an increasing trend. However, in arid regions, the temperature increase is more pronounced during colder months (1-3) compared to hotter months (6-9). The average annual runoff of SSP126 scenario showed an increasing trend from 2015 to 2100 (SSP126: 0.004/yr), while the runoff from the SSP245 and SSP585 scenarios showed a decreasing trend (SSP245: -0.031/yr; SSPSSP585: -0.084/yr). This is primarily attributed to a small increment of precipitation and a larger increment of temperature, an early melting of glacial snow and an increasing of evapotranspiration, which in turn leads to a reduction in annual runoff. The research can help achieving sustainable development, effective management of water resources in arid regions, and provide a reference and example for related research in high-resolution.