Sponge-city-based urban water system planning: a case study of water quality sensitive new area development in China

In recent years, sponge city has been booming in China aiming to alleviate urban flooding and improve water quality of natural water bodies. LID/green infrastructure has been gradually introduced to urban planning and urban water system planning. Efficient deployment of LID facilities is critical, which requires modeling and evaluation to develop rational planning. A case study of Guian New Area was presented to show the application of SWMM and the planning methods in sponge-city-based urban water system planning for water quality sensitive new areas development. Based on SWMM, two river network water quality models, the Dongmenqiao River and the Chetian River, were established through a systematic analysis of the case study area. Baseline scenarios were simulated and analyzed, and assimilation capacities of the two river basins were calculated by a trial-and-error method. Finally, two LID scenarios were carefully designed, simulated, and analyzed to support the planning. The simulations showed that in order to meet the strict water quality requirements in Guian New Area, large scales of LID facilities are required to cut down the rainfall-runoff pollution. Moreover, measures such as more frequent cleaning to reduce pollutants accumulation on the ground should also be taken to mitigate the maximum buildups of pollutants.