Evaluation of water supply and demand and optimization under the planting structure of cultivated land in the Hengshao Arid Corridor

Abstract

[Objective] This study aimeds to explore the water supply and demand dynamics of cropland from a planting structure perspective, achieve multi-objective optimization adjustments, and provide theoretical references for the principles of “allocating land based on water resources” and sustainable utilization of cropland resources. [Methods] Taking the Hengshao Arid Corridor as the research area and supported by various data sources including baseline meteorological data, land use, crop planting, and agricultural socioeconomic data, this study employed a crop water balance evaluation model to intricately reveal the water balance trends and irrigation requirements under diverse planting structures across various climate years from 1980 to 2020. A multi-objective optimization model for cropland planting structure was constructed under different irrigation water demand scenarios, incorporating multiple constraints related to water-land-crop. This led to the identification of optimized strategies for cropland planting structure. [Results] (1) Double-season rice and rapeseed have a more reliable water supply throughout their growth periods compared to single-season rice and maize. Rice demands higher water supply, especially during drought years, where the average water demand for double-season rice reaches as high as 608.29 mm. (2) The spatial distribution of effective precipitation and water demand patterns differs for rice and maize, exacerbating the drought situation in the southeastern part of the study area, whereas the water balance for rapeseed remains favorable. (3) The water deficit is more pronounced for double-season and single-season rice, with average net irrigation water requirements of 303.68 mm and 257.00 mm, respectively. Water supply-demand conflicts for drought-tolerant crops are less prominent, reducing the reliance on agricultural irrigation during the planting management process. (4) After optimization of the planting structure, the comprehensive benefits of cropland production can be significantly improved after setting water-saving targets and achieving optimal regulation, especially that the expected grain yield can be increased by 5.12% under the wet-year water constraints of the weighted scenario 3; and the net tax-reduced income from crop cultivation can be increased by 22.34% under the wet-year water constraints of the weighted scenarios 1 and 2. [Conclusion] The planting structure of the Hengshao Arid Corridor should basically remain unchanged in dry years. In normal years, the area of single-season rice can be appropriately increased and the proportion of dry crop planting can be reduced. In humid years, the planting area of grain crops can be significantly increased and the area of rapeseed can be reduced to improve the comprehensive benefits of cropland planting.

Keywords

• cultivated land|cropping structure|water supply and demand|irrigation demand|optimized utilization|hengshao arid corridor