Sustainable utilization of water resources in Wuling reservoir irrigation district based on the water footprint model

The crop production water footprint (WF) is of critical significance for evaluating the sustainable utilization of water resources in irrigation districts. Taking the Wuling Reservoir Irrigation District in Hubei Province as the research object, this study constructed an evaluation model for the sustainable utilization of irrigation district water resources based on crop WF, revealed the temporal evolution law of WF for major grain crops in the district from 1995 to 2024, and quantitatively assessed the sustainable utilization status of local water resources. The results showed that the WF in the irrigation district exhibited a fluctuating downward trend during the study period, decreasing from 7.16 m³/kg in 1995 to 4.34 m³/kg in 2024. Among them, the grey WF presented the most significant downward trend, while the blue WF and green WF maintained relatively steady changes, with their average values reaching 1.68 m³/kg, 1.19 m³/kg, and 2.02 m³/kg, respectively. The average WF of upland crops, early rice, middle-season rice and late rice was 1.56 m³/kg, 1.13 m³/kg, 1.09 m³/kg, and 1.08 m³/kg, respectively. The pressure of agricultural production on the water resource system in the irrigation district continued to decline, with the water resource pressure index dropping below 1.0 after 2000. The decoupling relationship between grain production and water pollution discharge became increasingly prominent, as evidenced by a 97.7% reduction in grey WF intensity. The level of sustainable water resource utilization in the irrigation district was gradually improved, with the coupling coordination degree of the water resource system rising from 0.32 to 0.74. The results of this study can provide a theoretical basis and decision-making reference for the sustainable utilization of agricultural water resources and planting structure optimization in irrigation districts of the Jianghan Plain.