title: Simplified continuous simulation model for investigating effects of controlled drainage on long-term soil moisture dynamics with a shallow groundwater table.
abstract: Accurate modeling of soil water content is required for a reasonable prediction of crop yield and of agrochemical leaching in the field. However, complex mathematical models faced the difficult-to-calibrate parameters and the distinct knowledge between the developers and users. In this study, a deterministic model is presented and is used to investigate the effects of controlled drainage on soil moisture dynamics in a shallow groundwater area. This simplified one-dimensional model is formulated to simulate soil moisture in the field on a daily basis and takes into account only the vertical hydrological processes. A linear assumption is proposed and is used to calculate the capillary rise from the groundwater. The pipe drainage volume is calculated by using a steady-state approximation method and the leakage rate is calculated as a function of soil moisture. The model is successfully calibrated by using field experiment data from four different pipe drainage treatments with several field observations. The model was validated by comparing the simulations with observed soil water content during the experimental seasons. The comparison results demonstrated the robustness and effectiveness of the model in the prediction of average soil moisture values. The input data required to run the model are widely available and can be measured easily in the field. It is observed that controlled drainage results in lower groundwater contribution to the root zone and lower depth of percolation to the groundwater, thus helping in the maintenance of a low level of soil salinity in the root zone.
authors.affiliation: School of hydropower and information engineering, Huazhong University of Science & Technology, Wuhan, 430074, China. huaiweisun@whu.edu.cn.
authors.forename: Huaiwei
authors.initials: H
authors.lastname: Sun
authors.affiliation: Key Laboratory of Groundwater Circulation and Evolution, Ministry of Education, China University of Geosciences, Beijing, 100083, China.
authors.forename: Juxiu
authors.initials: J
authors.lastname: Tong
authors.affiliation: State Key Laboratory of Water Resources and Hydropower Engineering Science, Wuhan University, Wuhan, 430072, China.
authors.forename: Wenbing
authors.initials: W
authors.lastname: Luo
authors.affiliation: Institute of agricultural water conservancy, The Yangtze River academy of Sciences, Wuhan, 430010, China.
authors.forename: Xiugui
authors.initials: X
authors.lastname: Wang
authors.affiliation: Institute of agricultural water conservancy, The Yangtze River academy of Sciences, Wuhan, 430010, China.
authors.forename: Jinzhong
authors.initials: J
authors.lastname: Yang
mesh_terms: D016573:Agrochemicals / Q000032:analysis; D002138:Calibration; D060587:Groundwater / Q000032:analysis*; D008962:Models, Theoretical; D054712:Salinity; D012987:Soil / Q000737:chemistry; D014867:Water / Q000032:analysis*; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D016573:Agrochemicals; D012987:Soil; D014874:Water Pollutants, Chemical; D014867:Water
keywords: Capillary rise; Controlled drainage; Deep percolation; Shallow groundwater level; Soil moisture balance