In Kumamoto, Japan, about one million people depend for all their water on groundwater resources. Paddy fields and rice farming in the middle river watershed area make a large contribution to the groundwater recharge. In our research, an environmental measure (artificial flooding for groundwater recharge) conducted by local governments is evaluated. Hydrological measurement was conducted in a paddy plot in the area. A simple model of water distribution was developed on the basis of the field measurement. Then, drought risk in the paddy-field district was estimated using the model and GIS data. The results reveal that the fields with a high percolation rate of more than 30 mm/d result in inefficient use of irrigation water although they have large potential for groundwater recharge. In addition, the water distribution model suggests that environmental measures can increase the risk of water shortage in the paddy-field district due to the farmers' careless use of water.

在日本的熊本市，约有一百万人的全部水都依赖于地下水资源。中游河流域的稻田和水稻种植对地下水的补给做出了很大贡献。在我们的研究中，对地方政府进行的环境措施（人工补给地下水）进行了评估。在该地区的稻田中进行水文测量。在现场测量的基础上，开发了一个简单的水分配模型。然后，使用模型和GIS数据估算了稻田区的干旱风险。结果表明，尽管渗滤潜力很大，但渗滤速率大于30 mm / d的田地导致灌溉水利用效率低下。此外，