Design of sponge city: Lessons learnt from an ancient drainage system in Ganzhou, China

This paper presents a case study on an ancient drainage system in the Hetao old urban center, Ganzhou, China, which is playing a key role in the prevention of urban flooding. The system includes ancient city walls, a Fushou ditch, and ponds. The ancient city walls were constructed to defend the river water intrusion. The Fushou ditch and ponds primarily served for the drainage and storage of the rainwater, respectively. The process of rainwater management in the Ganzhou ancient drainage system, including the guidance, storage, infiltration, purification and utilization, and drainage of rainwater, confirms the feasibility of the design concept of modern sponge city. Based on the lessons learnt from this ancient drainage system, the guideline for the rainwater management and design of sponge city is proposed. It is suggested that the sponge city should be planned before the new urban development. During the construction of sponge city, the dispersed ponds and the ditches made of durable and permeable materials in Ganzhou ancient drainage system are recommended to increase the amount of infiltration, storage and utilization of rainwater.