A GIS-based Approach To River Network Floodplain Delineation

The main goal of this continuing study is to develop a GIS-based procedure for delineating and displaying in 3-D the desired floodplain zones of river networks using data generated by the HEC-2 numerical model. The methodology is applied to the Bear Brook sub-watershed of the South Nation river system, located near Ottawa, Ontario, Canada. First, HEC-2 data are imported and reproduced in HEC-RAS. Next, HEC-RAS in-stream data are geo-referenced and mapped in GIS domain and then integrated with digital elevation model (DEM) over-bank data to build a terrain triangular irregular network (TIN) model. This integrated terrain model is then overlaid with water surface TIN for selected storm events for 3-D floodplain visualization. Data query models, relating to ‘local flood depth’ and ‘channel section’ information, are also constructed.