Floodplain Hydraulics: LiDAR Applications

As climate becomes increasingly variable, the costs to infrastructure and our society as a whole are going to rise drastically. Since the year 2000, damages due to hurricanes are estimated to be ~$260 Billion in the United States alone. This has led to changes in the national flood insurance program and could place more emphasis on flood modelling in the coming years. Here, we present a case study where remotely sensed data was used to increase the accuracy of a two-dimensional hydrodynamic flood model. The study site is a 14 km reach of the Tangipahoa River in Southern Louisiana. The reach has extensive floodplains with complex microtopography, making flowpath characterization difficult. Utilizing Light Detection and Ranging (LiDAR) data freely available from the state of Louisiana, a surface model was developed and storage zones within the floodplain were delineated. Further, information about the forest structure derived from the LiDAR was used to estimate each storage zone’s resistance to flow in the form of the Manning’s N coefficient. This produced a roughness estimation that more closely resembles the spatial heterogeneity of roughness experienced in the floodplain, thus increasing the predictive capability of the flood model.