Impacts of land use changes on water conservation in the Songhuajiang River basin in Northeast China using the SWAT model

Authors: DING, BEIBEI - China Agricultural University; LI, YUQIAN - China Agricultural University; Marek, Gary; GE, JIANING - China Agricultural University; HAN, YIWEN - China Agricultural University; HU, KELIN - China Agricultural University; YAN, TIEZHU - Ministry Of Ecology And Environment; ALE, SRINIVASALU - Texas A&M Agrilife; ZHANG, GUILONG - Ministry Of Agriculture - China; SRINIVASAN, RAGHAVAN - Texas A&M University; CHEN, YONG - China Agricultural University

Submitted to: Journal of Hydrology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/18/2024
Publication Date: 11/26/2024
Citation: Ding, B., Li, Y., Marek, G.W., Ge, J., Han, Y., Hu, K., Yan, T., Ale, S., Zhang, G., Srinivasan, R., Chen, Y. 2024. Impacts of land use changes on water conservation in the Songhuajiang River basin in Northeast China using the SWAT model. Journal of Hydrology. 306. Article 109185. https://doi.org/10.1016/j.agwat.2024.109185.
DOI: https://doi.org/10.1016/j.agwat.2024.109185

Interpretive Summary: Changes in crop composition within the Songhuajiang River Basin in China are occurring in response to government policy and overall crop profitability. Maize has been a staple crop in much of the region but conversion to soybean and rice is occurring in many areas. However, little consideration has been given to how these changes might affect regional hydrology and associated water conservation potential. Researchers form USDA-ARS Bushland, Texas A&M University, and China used a calibrated Soil and Water Assessment Tool (SWAT) model to simulate crop yield and crop water use of alternative crop composition scenarios including conversion to soybean and rice. Results indicated that conversion to soybean had minimal impact on regional hydrology and increased water conservation potential in most areas. Conversely, conversion to rice used considerably more water and included ecological risks to many areas. These findings suggest that conversion to soybean is advisable in the majority of the Songhuajiang River Basin to reduce crop water use and remain economically productive. Conversion to rice is not supported by the simulation results and more investigation should be performed before making basin-scale changes.

Technical Abstract: The Songhuajiang River Basin has experienced considerable changes in crop composition in recent years, which may lead to intense changes in basin hydrology and water conservation. Therefore, evaluation of the effects of these changes on the hydrological cycle and associated water conservation potential in the Songhuajiang River Basin is needed. A well-calibrated Soil and Water Assessment Tool (SWAT) model was used to simulate alternative crop composition scenarios in the basin including conversion of corn to soybean and corn to rice paddy, under both irrigated and dryland conditions. Results revealed that calibration of three crop yields for corn, rice, and soybean across 15 zones resulted in PBIAS values of -8.71~3.03, 6.15~19.72, and -8.69~7.16 percent, respectively. Good agreements were obtained for simulated results of streamflow in comparison with measured data from 12 hydrological stations, in which the overall NSE values for the calibration and validation periods were 0.60 and 0.64, respectively, and the overall PBIAS values were 7.8 and 5.4 percent. Following adjustments to crop composition, the hydrological cycle for corn to rice (all hydrological components changed by more than 18 percent) was more complex and intense than that of corn to soybean (all hydrological components change not exceed 5 percent). Based on the simulation results of water conservation potential, this study found the implementation of the policy of replacing corn with soybean in the Songhuajiang River Basin was feasible. As for the conversion of corn to rice, it is necessary to consider the substantial impacts on the hydrological cycle and the decline in water conservation potential. It is not recommended for producers in the South Songhua River basin to promote corn to rice based on simulation results.