Assessment of environmental improvement measures using a novel integrated model: a case study of the Shenzhen River catchment, China.

Integrated water environmental management in a rapidly urbanizing area often requires combining social, economic and engineering measures in order to be effective. However, in reality, these measures are often considered independently by different planners, and decisions are made in a hierarchical manner; this has led to problems in environmental pollution control and also an inability to devise innovative solutions due to technological lock-in. In this paper, we use a novel coupled system dynamics and water environmental model (SyDWEM) to simulate the dynamic interactions between the socio-economic system, water infrastructure and receiving water in a rapidly urbanizing catchment in Shenzhen, China. The model is then applied to assess the effects of proposed socio-economic or engineering measures on environmental and development indicators in the catchment for 2011-2020. The results indicate that 1) measures to adjust industry structures have a positive effect on both water quantity and quality in the catchment; 2) measures to increase the labor productivity, the water use efficiency, the water transfer quota or the reclaimed wastewater reuse can alleviate the water shortage, but cannot improve water quality in the river; 3) measures to increase the wastewater treatment rate or the pollutant removal rate can improve water quality in the river, but have no effect on water shortage. Based on the effectiveness of the individual measures, a combination of socio-economic and engineering measures is proposed, which can achieve water environmental sustainability in the study area. Thus, we demonstrate that SyDWEM has the capacity to evaluate the effects of both socio-economic and engineering measures; it also provides a tool for integrated decision making by socio-economic and water infrastructure planners.