A Novel Physically Based Distributed Model for Irrigation Districts’ Water Movement

Boyu Mi,Xiaojun Fu,Meiling Wei,Haorui Chen,Yinlong Jin,Jiangdong Jia,Xiaomin Chang,Shaoli Wang,Ronghua Chai

doi:10.3390/w13050692

Abstract

The water movement research in irrigation districts is important for food production. Many hydrological models have been proposed to simulate the water movement on the regional scale, yet few of them have comprehensively considered processes in the irrigation districts. A novel physically based distributed model, the Irrigation Districts Model (IDM), was constructed in this study to address this problem. The model combined the 1D canal and ditch flow, the 1D soil water movement, the 2D groundwater movement, and the water interactions among these processes. It was calibrated and verified with two-year experimental data from Shahaoqu Sub-Irrigation Area in Hetao Irrigation District. The overall water balance error is 2.9% and 1.6% for the two years, respectively. The Nash–Sutcliffe efficiency coefficient (NSE) of water table depth and soil water content is 0.72 and 0.64 in the calibration year and 0.68 and 0.64 in the verification year. The results show good correspondence between the simulation and observation. It is practicable to apply the model in water movement research of irrigation districts.

Highlights

A novel physically based distributed model (IDM) specialized for the water movement in irrigation districts is proposed in this study
The water flow in irrigation canals and drainage ditches is governed by the 1D diffusive wave equation
The soil water movement is governed by the 1D Richards equation and integrated into the regional scale

Summary

Introduction

Hydrological modeling, as a supplement to the theoretical and experimental study at the beginning, is undergoing rapid development due to the accelerated progress of computer science and numerical techniques [2]. Tremendous efforts have been made for the development and application of hydrological models, of which many were adopted in the study of water movement in irrigation districts directly or in a combinative or improved way. Irrigation districts are quite different from usual regions considered in generalized hydrological models. There are more artificial regulations in irrigation districts to control the water flow, which complicates the water distribution and movement compared to natural regions. The water distribution through irrigation canals is controlled by the gate system, which is hard to describe in a hydrological

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Conclusion