In 2014, China initiated a nation-wide ‘Sponge City’ concept to tackle urban water challenges. The idea was to design cities such that they could absorb, capture and repurpose rainwater to improve flooding situations in the cities. We were commissioned by one of the largest engineering survey and design corporations in China to evaluate the construction planning and assess the flood risks of Dagang, a town in Nansha District, Guangzhou.

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Challenge

Dagang is vulnerable to flood disasters because of its low elevation and combined influence of heavy rainfall, offshore tide level and typhoon. In order to reduce potential impact of flood events, it was decided that the sponge city initiative – which would help decrease runoff rate and alleviate losses caused by floods – should be implemented in this area. Our client, China Railway Eryuan Engineering Group Co. Ltd, needed a waterlogging assessment and an evaluation of the sponge city construction plans. We used MIKE Powered by DHI software to build two different models to address these objectives.

Suitability analysis in study area. © DHI

Solution

Evaluation of sponge city construction plans
Based on the local sponge city construction index system, the research area was divided into three different management units. The indicators for the entire area were categorised into individual plots and municipal roads. Our Sponge City Aided Design (SCAD) software, was utilised to analyse and evaluate whether designed low impact development (LID) infrastructures could reduce the runoff volume and improve water quality of rivers efficiently.

Flood risk assessment
In the research area, there was no pipe network, so only surface flow should be considered for flooding risk analysis. With client’s data as input, including DEM, rainfall data, underlying data, external water level and so on, we constructed a hydraulic model using MIKE 21 Hydrodynamics (HD) Flow Model. The flooding result also contributed to the optimisation of the sponge city master plan.

Flooding risk in research area. © DHI

Results

Validated the efficacy of the sponge city plan on pollutant reduction and runoff rate control

Detected increased flood risk in two industrial zones and proposed mitigation measures

Overall optimisation of the sponge city master plan

‘We were able to validate the effectiveness of our construction plans and assess potential flood risk in the city thanks to DHI's expertise in water modelling. The work was delivered on time and with precision - we would recommend DHI anytime.’

Lihua Chen, Project Manager
China Railway Eryuan Engineering Group Co. Ltd

About the client

China Railway Eryuan Engineering Group Co. Ltd was established in 1952, and it is affiliated to China Railway Group Corporation – one of top 500 companies in the world. The company is one of the largest engineering comprehensive survey and design enterprises in China and has won the National Science and Technology Progress Award twice.

Software used

SCAD (Sponge City Aided Design)
MIKE 21 Hydrodynamics (HD) Flow Model

Case story - Highlights flyer


An assessment of Nansha Sponge City construction

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