Integration of 2-D hydraulic model and high-resolution lidar-derived DEM for floodplain flow modeling

D Shen,X Cheng,Y Rui,S Ye,J Wang

doi:10.5194/hess-19-3605-2015

Abstract

Abstract. The rapid progress of lidar technology has made the acquirement and application of high-resolution digital elevation model (DEM) data increasingly popular, especially in regards to the study of floodplain flow. However, high-resolution DEM data pose several disadvantages for floodplain modeling studies; e.g., the data sets contain many redundant interpolation points, large numbers of calculations are required to work with data, and the data do not match the size of the computational mesh. Two-dimensional (2-D) hydraulic modeling, which is a popular method for analyzing floodplain flow, offers highly precise elevation parameterization for computational mesh while ignoring much of the micro-topographic information of the DEM data itself. We offer a flood simulation method that integrates 2-D hydraulic model results and high-resolution DEM data, thus enabling the calculation of flood water levels in DEM grid cells through local inverse distance-weighted interpolation. To get rid of the false inundation areas during interpolation, it employs the run-length encoding method to mark the inundated DEM grid cells and determine the real inundation areas through the run-length boundary tracing technique, which solves the complicated problem of connectivity between DEM grid cells. We constructed a 2-D hydraulic model for the Gongshuangcha detention basin, which is a flood storage area of Dongting Lake in China, by using our integrated method to simulate the floodplain flow. The results demonstrate that this method can solve DEM associated problems efficiently and simulate flooding processes with greater accuracy than simulations only with DEM.

Highlights

Floodplain flow simulation is important for forecasting floods and assessing flood-related disasters
2-D hydraulic models have emerged as a standard for predicting flood conditions in academic contexts and in technical applications; 2-D approaches have largely replaced 1-D approaches that, despite their efficiency and potential for improvement in compound channels, present conceptual problems when applied to overbank flows (Gichamo et al, 2012; Abu-Aly et al, 2014; Costabile et al, 2015)
The resolution of the 2-D hydraulic model mesh was above 100 m, whereas the proposed method mentioned above interpolates the water level through a 1 m high-resolution digital elevation model (DEM)

Summary

Introduction

Floodplain flow simulation is important for forecasting floods and assessing flood-related disasters. 2-D hydraulic models have emerged as a standard for predicting flood conditions in academic contexts and in technical applications; 2-D approaches have largely replaced 1-D approaches that, despite their efficiency and potential for improvement in compound channels, present conceptual problems when applied to overbank flows (Gichamo et al, 2012; Abu-Aly et al, 2014; Costabile et al, 2015). Until the advent of survey technologies such as lidar, computational flood hydraulics was increasingly limited by the data available to parameterize topographic boundary conditions rather than the sophistication of model physics and numerical methods. New distributed data streams, such as lidar, pose the opposite problem of determining how best to use their vast information content optimally within a compu-

Methods

Results

Discussion

Conclusion