Quantitative evaluation of roles of farm land on water resource.

定量评价农田在区域水文循环和水资源中的作用具有重要意义。在本项目中，对一些实验流域和一个冲积面进行了调查和研究，以评价其作用。结果总结如下：1。流域蒸散量的分析表明，流域蒸散量依赖于流域的湿度，且这种依赖在旱地中更为明显。降雨损失受初始湿润条件和渗流特性的影响。流域渗流强度的比较结果表明，流域渗流强度受土壤类型和土地利用方式的影响。提出了一种定量评价集水区对河流流量作用的方法。定义了流量稳定指数，并对森林流域和旱地流域的流量稳定指数进行了比较。结果表明，森林比旱地更能保持河流的稳定。3 .冲积区结果为：地表水量收支分析表明，灌溉期地下水补给量大于非灌溉期，说明水田对该地区地下水的重要性。建立了包括地下水系统在内的集总参数模型，分析了该地区的水文循环，评价了该地区的水平衡状况。

It is very important to evaluate quantitatively roles of farm land on hydrologic cycle and water resource in regions. In this project, investigations and researches have been carried out in some experimental catchments and a alluvial plane to evaluate the roles.The results are summarised as follows for the catchments ;1. The analysis of evapotranspiration from the catchments revealed that evapotranspiration depends on wetness of the catchment and the dependency is more dominant in the upland filed.2. Rainfall loss is infuluenced by the initial condition of wetness and the percolation property. The comparison of estimated intensities of percolation in the catchment showed that the intensity is influenced by the type of soils and land use.3. A method was proposed to evaluate quantitatively the role of catchments on stream flow. A index of flow stabilization was defined and the values of the index were compared between the forest catchment and upland field catchment. It was shown that the forest keeps stream flow more stable than the upland field.The results for the alulvial area are ;4. The water budget analysis in the surface region showed that the groundwater recharge in irrigation periods is more than in non-irrigation ones and it means the importance of paddy field for the groundwater in the region.5. A lumped parametric model, which included the groundwater system, was developed to analyze the hydrologic cycle to evaluate the water balance in the region.