Hydrogeological constraints and opportunities for “Sponge City” development: Shenzhen, southern China

Abstract

Study area: Shenzhen Megacity, southern China. Study focus: “Sponge City” is a Chinese concept aimed to mitigate flood risk, tackle chronic water scarcity, and improve the urban environment. It consists of a combination of new storage and infiltration facilities distributed on a large scale. The concept is similar to strategies and developments already adopted in the Western world. In this paper, new constraints on the interactions between the sponge facilities, the landscape and the subsoil are identified for a hilly, sub-tropic terrain. New hydrological insights for the region: Using a geomorphological zonation at the catchment scale, a conceptual model is proposed for southern China to identify areas where groundwater infiltration and storage is feasible. The proposed model is applied to Shenzhen, a megacity in southern China chosen as a pilot site for Sponge City, with 24 project areas already identified. Our zonation approach suggests that project areas on the coastal plain and reclaimed land will only work with above-ground storage, while there is significant potential to enhance many of the other pilot areas with infiltration facilities. The conceptual model improves the Sponge City approach aimed at increasing the managed annual runoff; it also mitigates the waterlogging risk. At the same time, the proposed conceptual model has moderate costs and makes possible the application of the Sponge City concept in other urban areas of southern China. Keywords: Conceptual model, Flood mitigation, Groundwater, Urban planning, Urban waterlogging, Wet climate