Study on evaluation of water environment in basin by a composite model of hydrological regime and agricultural water use.

灌溉通常需要大量的水，并且在历史上优先于其他用途。它还影响河流流量，在干旱时期，它们的关系影响流域管理。为了评价流域水环境，这是强烈影响的关系，模拟模型的基础上，“复杂的坦克模型”。并应用该模型对日本某流域的农业水资源供需、灌溉水再利用系统和农田退水进行了分析。分析结果表明，灌溉系统已经建立了有效的再利用系统，回流形成了河流流量的大部分。在干旱时期，应重点关注决定水库供水的临界点，并保持该点的充分排放，以利用水资源。模型中设置了污染物径流子模型，并利用该模型估算了河流水体中营养盐浓度和负荷。

Irrigation generally needs much water and has an historically established priority over other uses. It also affects river discharge, and in drought periods their relation influences the basin management. To evaluate the water environment in a basin, which is strongly affected by the relationship, a simulation model was developed, based on the "Complex Tank Model". And it was used to analyze agricultural water demand and supply, a water re-use systems of irrigation, and return flow from farmland in a river basin in Japan. Results of analysis made clear that irrigation systems have built up effective re-use systems and that return flow forms the greater part of the river discharge. It was also noted that, in drought periods, the critical point deciding the water supply from the reservoir should be focused on and maintaining the adequate discharge at the point leads to the utilization of water resources. Pollutant run-off sub-model was set in the model and also used to estimate the nutrient concentration and load of the river water.