Impacts of change in multiple cropping index of rice on hydrological components and grain production in the Zishui River Basin, Southern China

Authors: YUAN, CHENGCHENG - China Agricultural University; LI, XINLIN - China Agricultural University; WU, YUFENG - University Of Maryland; Marek, Gary; ALE, SRINIVASULU - Texas A&M Agrilife; SRINIVASAN, RAGHAVAN - Texas A&M University; CHEN, YONG - China Agricultural University

Submitted to: Agricultural Water Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/19/2025
Publication Date: 5/23/2025
Citation: Yuan, C., Li, X., Wu, Y., Marek, G.W., Ale, S., Srinivasan, R., Chen, Y. 2025. Impacts of change in multiple cropping index of rice on hydrological components and grain production in the Zishui River Basin, Southern China. Agricultural Water Management. 316. Article 109572.
DOI: https://doi.org/10.1016/j.agwat.2025.109572

Interpretive Summary: China is the largest producer and consumer of rice globally. The Zishui River Basin (ZRB) in the Hunan Province has long been one of the most productive rice producing regions in the world. Sustaining stable rice production by maintaining areas of double cropping are central to the national and world food security strategy. However, environmental concerns and economic pressures have resulted in decreased rice acreage being double cropped in the region, resulting in decreased yield and increased food insecurity. Researchers from the China Agricultural University, USDA-ARS, and Texas A&M University used a calibrated Soil and Water Assessment Tool (SWAT) model to explore simulated alternative cropping scenarios for sustainable rice production in the region. Results indicated that a mix of single and double cropped rice acreage in the region resulted in increased yield with only minimal changes to hydrological components.

Technical Abstract: Recent declines in the rice Multiple Cropping Index (MCI) have caused substantial regional changes in both grain production and hydrology in Southern China. This study examined current and projected changes in rice MCI for the Zishui River Basin (ZRB) in the Hunan Province to evaluate hydrological impacts. The current rice land use scenario (S0) was determined to be 27.4 percent single cropping and 72.6 percent double cropping using high-resolution remote sensing to extract planting areas. A planting suitability evaluation for double cropping rice in the ZRB was based on climate, soil, and topography parameters, resulted in 16.7 percent of land being suitable for single cropping and 83.3 percent for double cropping. Additionally, the S0 scenario was used to construct and parameterize the Soil and Water Assessment Tool (SWAT) model, which demonstrated excellent streamflow simulation with Nash-Sutcliffe efficiency (NSE) and percent bias (PBIAS) values of 0.83 and 1.0 percent during calibration, and 0.85 and -0.8 percent during validation. Rice yield evaluation was satisfactory, with PBIAS values of -1.2 percent and 2.2 percent for single cropping, and 1.3 percent and -2.4 percent for double cropping during calibration and validation. Alternative scenarios included a 100 percent single cropping rice (S1), 100 percent double cropping rice (S2), and a mixed double and single cropping rice (S3). Simulation results indicated that the S3 optimized rice land use scenario was the preferred rice MCI approach with minimal impacts on hydrological elements but increased rice yield. Changes in irrigation, evapotranspiration, percolation, water yield, and rice yield for S3 were 4.9, 0.8, 2.6, 1.4, and 4.3 percent, respectively. In contrast, the S2 scenario resulted in a greater yield increase of 10.8 percent, but with considerable changes in some hydrological elements, most notably a marked increase in irrigation of 12.1 percent. This study emphasized the importance of integrating remote sensing with watershed-scale hydrological models to assess the impact of changes in the MCI on hydrology and grain yields. Given the favorable conditions in the ZRB, this study recommended adjusting current rice MCI and layout to optimize cropping patterns and support sustainable agriculture.