DRAINMOD is a computer simulation model, which simulates the hydrological conditions of poorly drained high water level soil hourly with a long climate record (for example, 50 years). The model predicts the impacts of drainage and related water management practices on groundwater table, soil moisture status and crop yield. The parallel method is mainly used to analyze the hydrological conditions of some types of wetlands to determine whether the wetland hydrological standards meet the requirements of drainage or part of the drainage site. The model is also used to determine the hydropower capacity of the sewage treatment system. The model has been successfully tested and applied to various geographical and soil conditions. Over the past 20 years, the model's capacity has been extended to predict the impact of drainage and water resource management practices on hydrology and water quality in farmland and watershed wide agriculture and woodland.