A GIS-supported Impact Assessment of the Hierarchical Flood-defense Systems on the Plain Areas of the Taihu Basin, China

International Journal of Geographical Information ScienceInternational Journal of Geographical Information Science, Volume 26, Issue 4, 2012

Chaoqing Yu, Xiaotao Cheng, Jim Hall, Edward P. Evans, Yanyan Wang, Changwei Hu, Haoyun Wu, Jon Wicks, Mathew Scott, Haitao Sun, Jing Wang, Minglei Ren & Zongxue Xu

“The Taihu Basin is located in the east coast of China, with a total area of 36,895 km2. Low-lying floodplain areas occupy about 83% of the basin. The threat of frequent floods to this economically important area has stimulated construction of enormous flood-defense projects along the complex system of rivers and lakes. Digital modeling of flooding processes and quantitative assessment of flood damages in this basin remain challenging due to the complexity. This article reports on an approach to simulate the flooding processes, which integrates hydrological and hydraulic modeling with dike-reliability analysis and socioeconomic information within a GIS platform. A new algorithm is introduced to calculate the influence of the flood-defense systems on spatial distributions of floodwater and consequential damages. Scenario analysis indicates that the modeling is particularly sensitive to the assumed rainfall, dike reliability, and the pump capacities within local polders. The model is validated by comparison with observations from historical flood records. The analysis reveals that the defense systems have significantly reduced the basin-wide flood risk and changed the spatial distributions of floodwater. Such a GIS-based approach can be potentially used to assess the benefit from construction of flood defenses and to avoid unintended spatial redistribution of flooding.”