Enhanced freeze-thaw cycle altered the simulations of groundwater dynamics in a heavily irrigated basin in the temporate region of China

Authors: LI, BAOGUI - China Agricultural University; TAN, LILI - China Agricultural University; ZHANG, XUELIANG - China Agricultural University; QI, JUNYU - University Of Maryland; Marek, Gary; FENG, PUYU - China Agricultural University; LIU, DE LI - Wagga Wagga Agricultural Institute; LUO, XI - University Of Maryland; SRINIVASAN, RAGHAVAN - Texas A&M University; CHEN, YONG - China Agricultural University

Submitted to: Water Resources Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/20/2024
Publication Date: 8/31/2024
Citation: Li, B., Tan, L., Zhang, X., Qi, J., Marek, G.W., Feng, P., Liu, D., Luo, X., Srinivasan, R., Chen, Y. 2024. Enhanced freeze-thaw cycle altered the simulations of groundwater dynamics in a heavily irrigated basin in the temporate region of China. Water Resources Research. 60(9). Article e2023WR036151. https://doi.org/10.1029/2023WR036151.
DOI: https://doi.org/10.1029/2023WR036151

Interpretive Summary: Expected increases in air temperature and atmospheric carbon dioxide concentration associated with climate change may pose a substantial risk to global food security in both irrigated and rainfed crop production regions. Computer simulation modeling using the Soil and Water Assessment Tool (SWAT) model with general circulation models and shared socioeconomic pathways may help develop appropriate management strategies to promote groundwater conservation. However, the SWAT model lacks for simulation of hydrologic processes in regions with seasonally frozen soils like the North China Plain. Therefore, researchers from USDA-ARS Bushland and university partners from the U.S., Australia, and China developed a soil freeze-thaw cycle module for the SWAT. Simulations using the improved SWAT model suggested increased variability of infiltration during winter months related to freeze thaw cycling and irrigation of overwinter crops. These differences resulted in spatial and temporal differences in shallow groundwater tables with respect to different climate scenarios. These findings suggest that accurate simulation of soil freeze thaw effects is necessary for meaningful simulation of hydrologic processes in regions with shallow groundwater tables.

Technical Abstract: With intensified global warming, accurate quantification of hydrological processes in seasonally frozen regions, particularly with irrigated overwinter crops, is necessary to develop management strategies that promote groundwater conservation. By incorporating a physically-based freeze-thaw cycle module into the Soil and Water Assessment Tool (SWAT) model, variations of surface hydrology and groundwater dynamics were systematically assessed in North China Plain under three SSPs during 2041-2070 and 2071-2100 between the conventional and improved SWAT models. Both models consistently predicted decreased soil evaporation and increased canopy interception in all three scenarios compared to the historical period (1971-2000). The differences in canopy interception and actual evapotranspiration were insignificant as simulated between the two models while noticeable changes were presented in soil evaporation and crop transpiration. Compared to the conventional SWAT model, the simulation differences were more pronounced for irrigation, percolation, and shallow groundwater levels, particularly during the winter wheat growing season. Additionally, the improved SWAT model projected that the average change rates of shallow groundwater levels were approximately 0.90 +/- 0.16 m yr-1 (SSP1-2.6), 0.60 +/- 0.46 m yr-1 (SSP2-4.5), and -0.17 +/- 0.53 m yr-1 (SSP5-8.5), respectively, during 2041-2070 compared to the historical period. The improved SWAT simulations showed that the spatial distributions of decline rates in shallow groundwater tables were projected to slowly decline or even rise by the end of the 21st century under SSP5-8.5. Our study emphasized the importance of considering the freeze-thaw processes to accurately evaluate groundwater variations in response to climate change effects in temperate regions with an overwinter crop.