Evaluating the effects of single and integrated extreme climate events on hydrology in the Liao River Basin, China using a modified SWAT-BSR model

Authors: ZHANG, YINGQI - China Agricultural University; GE, JIANING - China Agricultural University; QI, JUNYU - University Of Maryland; LIU, HAIPING - China Agricultural University; ZHANG, XUELIANG - China Agricultural University; Marek, Gary; DING, BEIBEI - China Agricultural University; FENG, PUYU - China Agricultural University; LIU, DE LI - Wagga Wagga Agricultural Institute; SRINIVASAN, RAGHAVAN - Texas A&M University; CHEN, YONG - China Agricultural University

Submitted to: Journal of Hydrology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/3/2023
Publication Date: 6/7/2023
Citation: Zhang, Y., Ge, J., Qi, J., Liu, H., Zhang, X., Marek, G.W., Ding, B., Feng, P., Liu, D., Srinivasan, R., Chen, Y. 2023. Evaluating the effects of single and integrated extreme climate events on hydrology in the Liao River Basin, China using a modified SWAT-BSR model. Journal of Hydrology. 623. Article 129772. https://doi.org/10.1016/j.jhydrol.2023.129772.
DOI: https://doi.org/10.1016/j.jhydrol.2023.129772

Interpretive Summary: Extreme weather events associated with climate change may pose a substantial risk to global food security. Although the impacts of such events are unknown, simulation modeling using global circulation models may provide insight into potential effects on crop production and soil and water resources. Researchers from USDA-ARS Bushland and university partners from the U.S., Australia, and China simulated the effects of single and complex events including extreme temperatures, precipitation, and drought for the Black Soil Region of Liao River Basin (LRB) in China through the end of the 21st century. Simulations using a modified Soil and Water Assessment Tool (SWAT) model equipped with an improved CO2 algorithm and alternate freeze-thaw function (SWAT-BSR) suggested both extreme hot and cold temperatures resulted in reductions in hydrologic components of the water cycle. The negative effects of extreme temperature and precipitation were more pronounced on dryland and limited irrigation areas. These findings may aid in the development of alternative management strategies for mitigating the effects of extreme climate events in other black soil regions.

Technical Abstract: Extreme climate events may have a substantial impact on water conservation in the black soil region of China. This study integrated a dynamic CO2 input method and an alternative freeze-thaw cycle function into Soil and Water Assessment Tool (SWAT) to create a SWAT-Black Soil Region (SWAT-BSR) model. The SWAT-BSR model was used to simulate future climate scenarios in the Liao River Basin (LRB; 220,000 km2) and an R script was developed to extract days in which extreme climate events occurred along with corresponding hydrological variables. Extreme climate events included extreme heat, cold, precipitation, and drought events across seven zones in the LRB. Subsequently, we explored the changes in single and integrated extreme climate events during the historical period (1971-2000) and future periods (2041-2070 and 2071-2100) under the SSP2-4.5 and SSP5-8.5 scenarios. The results indicated that each hydrological variable was reduced under extreme cold and drought events compared to the historical period. Canopy interception and percolation were decreased under extreme heat in the future periods while extreme cold was opposite with a pronounced negative impact on reference evapotranspiration and soil evaporation. In contrast, each hydrological variable under extreme precipitation increased relative to the normal conditions while hydrological variables were largely negatively affected under extreme drought. In addition, the integrated extreme climate index increased over time, with more pronounced changes under the SSP5-8.5 scenario than those of SSP2-4.5 scenario. Hydrological variables were most at risk in the dryland zones as compared to irrigated or deficit-irrigated zones. These findings indicated that more attention should be given to the impacts of extreme climate events on water losses from both historical and future perspectives. It is also necessary to develop mitigation strategies for water conservation in the LRB based on the extreme climate events projected to occur in different zones and periods in the future.