A distributed irrigation district model for differentiating drainage water sources in irrigation districts

FU Chuanxing; WU Yuxiao; CHEN Haorui; ZHANG Baozhong; MI Boyu; MIAO Ping; ZHENG Hexiang

doi:10.13522/j.cnki.ggps.2025316

Abstract：[Objective]Accurate identification of drainage sources in irrigation districts is essential for optimizing water resource management and improving drainage efficiency.However,the complex interactions between irrigation and precipitation make it difficult to quantify their respective contributions.This paper presents a method for identifying drainage sources in irrigation districts and quantifying the respective contributions of irrigation and precipitation to drainage water.[Method]The method is based on a distributed hydrological model,termed the Irrigation District Model(IDM),to simulate the drainage process using field survey data and measured observations.The model was first calibrated and validated against field data collected from 2023 to 2024.The validated model was then used to analyze changes in drainage water and its composition under different irrigation and precipitation scenarios.A multiple linear regression model relating total drainage volume to irrigation and precipitation was established to quantitatively differentiate drainage sources.[Result]①The IDM-simulated results showed good agreement with observed data,demonstrating its effectiveness in simulating hydrological processes in irrigation districts.②Both drainage volume and its composition were influenced by irrigation and precipitation,with surface drainage showing greater sensitivity to these inputs.Across different hydrological years,subsurface drainage was dominant.Its contribution was highest in dry years(78%)and least in wet years(65%),with normal years(70%)in between.③Overall,approximately 47.01%of the total drainage originated from irrigation,with the remaining 52.99%attributed to precipitation.[Conclusion]The proposed IDM can accurately simulate drainage processes in irrigation districts and quantify the respective contributions of irrigation and precipitation to drainage.The model can be used to support improving water resource management and drainage regulation in irrigation districts.