Abstract:In order to buffer the spatial conflicts and problems of water environment, water safety and water ecology in mountainous cities, a constructed wetland system in the upper reaches of the Liangtan River has been built as a pilot project, to cooperate the riparian zone restoration and assist in improving the water quality of the river. To adapts to the spatial constraints of the mountainous landform and different demand of the urban development in the near and long term. the "reverse design" and "dynamic design" methods have been used in the design, while the design parameters determined according to local conditions, and the future operation parameters are checked. The wetland system was designed as a river bypass wetland in the near term, and as a rainwater wetland of the sponge city system in the future. The results show that the bypass wetland can stably purify river water of lower than Class V into Class V water quality to reach the recent goal, and the main water quality indicators of effluent, except TP, can even reach Class II or III. It is predicted the constructed wetland also can meet the future need of storage and purification functions of the sponge city system. The pilot project shows that the riparian constructed wetland system has a significant effect on reducing the pollution load into the river, especially the transportation of nutrients, and at the same time has the functions of urban flood control, ecology and landscape transition, and is sustainable. The design method can provide reference for river management in similar mountainous cities.
