GIS Based Hydrodynamic Model And Its Application In Flood Risk Mapping

With the development of information technology and fundamental fluid theory, hydrodynamic mathematical model has become even more important in different areas including scientific research, engineering design, environment and ecology impaction assessment.Based on traditional hydrodynamic model, the paper constructed the methodology scheme and method to suit for the complicated boundary, concerned about the non-uniform setting velocity, bedload grain size adjustment and lateral deformation. Aims to meet the future requirement of research and practical cases, the established model is combined with pre-processing and post-processing system based on GIS.As for the unbalance momentum induced from water pressure non-uniform with river bed slope, the Gauss theory is used to calculate averaged flux of each side, which not only avoids the error flow phenomena for steep water depth gradient, but also shows the distribution of status vectors correctly.As for the cross-section measured data treatment which guarantee to the correct boundary condition, Douglas-Peucker method is used for deriving the characteristic points to classify the main channel, floodplain and temporary dike effectively.By using ArcGIS and secondary developing with ArcGIS, the model's pre-processes and post processes which including digital elevation generation system and flow field visualization system ,not only improve the efficiency but also improve the precision of digital elevation generation, information searching speed and visualization technology obviously.After the model verification, sets of scenario studies are carried out in the floods risk map of Dongpinghu Lake including different flood probability of occurring once per 50 years, 100 years and 1000 years. The model is applied to justify the flood risk map in terms of the flood proceeding route, flood arrival time, flooding area and flow velocity distribution analysis.