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Guan Tang New District Ecological Drainage System “Sponge City” Design

Preparation of an ecological drainage plan for Guan Tang district with a basin of approximately 12 km2 in size. The ecological drainage plan focus included source control of stormwater runoff, urban flood control and waterlogging drainage engineering measures.  Much of the plan was derived utilising Low Impact Development technology guidelines applied to the local conditions and characteristics. The objectives of this project were to achieve a balance of water quality, ecological landscaping and comprehensive flood control, in order to contribute to the construction of a "low carbon, ecological, smart, liveable" city.

Flood risk of design 50-year storm event in Guan Tang new district

Main tasks:

- Adapting Low Impact Development (LID) including Technology Transfer from New Zealand to identify three stormwater management levels and determine the different runoff control targets including water quality volume, extended detention volume, peak flow reduction volume based on local hydrological characteristics;

- Preparation of LID guidelines in accordance with local hydrological characteristics and specify design, construction and maintenance methods for swale, rain garden, green roof, rain tank, retention pond, wetland and other LID options;

- Identification of flood risk areas, determination of overland flow paths, optimisation of land use and elevation planning through computer simulation;

- Comprehensive consideration for the utilisation of rainwater, pollution source control, urban green corridor designed as a natural overland flow path during flooding events, water resources balance and land use planning;

- Design and preparation of river system and ecological drainage layout plan for Guan Tang new district, including the backbone river system layout, channel sizing, typical cross sections, design flood levels and volumes, dam location and height, scale of landscape lake, design details of weir, layout and scale of retention ponds, and establishment of overland flow paths for extreme flood events.