Development of Integrated Water Environment Management Models in Urbanizing Agricultural Watersheds in Asian Monsoon Region

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In this research, we have been aiming at the development of integrated water environment management models with the function of predicting and evaluating the watershed nutrient runoff loads of nitrogen and phosphorous from urbanizing agricultural watersheds in Asian monsoon region. The distributed-parameter models have been constructed by utilizing GIS techniques together with the detailed watershed information such as DEM, land utilization, river network and point sources. The prediction accuracy has been improved by innovating artificial intelligence techniques and time-frequency analyses when modeling sub-processes of nutrient runoff loads from various sources and water quality dynamics in closed water bodies, because it is generally difficult to quantify those sub-processes accurately.The model construction and validation have been conducted at two watersheds that have entirely different watershed characteristics, the Chikugo River watershed and the Zuibaiji River watershed. The Chikugo River watershed has a largest watershed area in Kyushu Island, Japan and a huge variety of land utilization in the watershed, while the Zuibaiji River watershed is located at the west of Fukuoka City, Japan and a typical urbanizing agricultural watershed with a relatively small watershed area. The models have been constructed and validated in the watersheds by quantifying each of sub-processes and connecting sub-models with each other.