Construction of the urban water environmental pollution control system based on the ecological ideas of water sensitive urban design

Abstract

For the first time in history, the majority of the world’s population is located in urban areas. This milestone marks a critical turning point that will dramatically affect land and water environments. Increasingly, our cities need to be designed for adaptability and resilience to the impacts of population growth, urban densification, and increase in impervious areas, on the urban water environment. The water sensitive urban design (WSUD) has evolved from its early association with stormwater management to provide a broader framework for sustainable design and urban water management. It provides a common and unified method for integrating the interactions between the urban built form and the urban water cycle environment. This paper presents an overview of theory meaning, key principles, and technical architecture of WSUD, and at the same time, ecological ideas of WSUD has been summarized combined with the traditional ecological wisdom, which comprises the “all things together”theory, the idea of “daofaziran”(following nature’s lead), “design with nature”, and the idea of “ecological systems”. WSUD technologies include green roofs, rain gardens, bioswales, soakaways, wet basins, dry basins, etc. However, to date, few studies have been conducted on the classification of all of the current technologies. In this paper, the WSUD technologies are categorized into three types according to the functions of different technologies: Water Balance, Water Quality, and Water Conservation. For the development of the WSUD worldwide, especially in China, which faces a more serious challenge because of rapid urbanization, further studies on creating technical architecture and summarizing ecological ideas are required. Kaixian Country located in the Three Gorges Reservoir area has become a representative water-sensitive urban area because of the water level control, splitting urbanization speed, and accompanying potential water environment crisis. In order to explore an fitting ecological restoration model to overcome the contradiction between high-speed urbanization and water environment security, this paper employs Kaixian as the example to design the urban water environmental pollution control system, based on the understanding of the ecological ideas of WSUD and the application of the WSUD technology. The whole design was divided into three parts: source control, process control, and receiving water control. The source control mainly used the green roof-ecological wall-rain garden system to decrease the source of pollutants; the process control was divided into four belts: recreation belt, ecological slope belt, landscape dick- pond belt, and natural drawdown belt, different WSUD strategies were implemented for every belt and some possible solutions were proposed for the contaminated urban water bodies. This design includes multi-stripe and multi-function modes that consider not only the physical elements of a place that provide the functional value, but also those elements that create a congenial atmosphere by enhancing the ‘sense of place’ (psychological value). The “multi-tape mode” will provide a good example of controlling water pollution for other urban areas located in the TGR region.