Model‐Based Multi‐Objective Optimisation of Autumn Irrigation Strategies to Balance Water Productivity, Economic Returns and Soil Salinity Control in Hetao Irrigation District
Jing Xue, Yingxue Wu, Junfeng Chen, Lihong CuiABSTRACT
Autumn irrigation plays a crucial role in alleviating soil salinisation in the Hetao Irrigation District (HID), but its high water consumption and low efficiency require regional optimisation. An integrated eco‐hydrology simulation and optimisation framework was applied, where a distributed SWAP–WOFOST model was coupled with multi‐objective decision analysis. The distributed SWAP–WOFOST model reliably reproduces the coupled dynamics of crop growth and soil water, salinity and temperature. The average annual spring wheat yield was 5332–5517 kg/ha, and the WP (water productivity) was 1.25–1.27 kg/m 3 under different autumn irrigation patterns from 2000 to 2017. The optimal irrigation strategies were in Dengkou County, the autumn irrigation date was mainly after 20 October, and the average autumn irrigation quota was 189 mm; in Hangjinhouqi and Linhe District, mainly between 10 October and 20 October, the quotas were 171 and 172 mm, respectively; and in Wuyuan County and Wulateqianqi, mainly before 10 October, the quotas were 157 and 158 mm, respectively. The optimal autumn irrigation strategies maintain a stable average spring wheat yield of 5506 kg/ha and WP of 1.27 kg/m 3 . Compared with the baseline irrigation mode (150 mm on 15 October), economic returns were improved by about 5%.