Performance of 1D and 2D hydraulic models for flood simulation

Nowadays, the availability of high resolution Digital Elevation Models (DEMs) to represent the earth surface allows coupling of hydraulic models with Geographic Information Systems (GIS) to obtain the flood extent and water levels in floodplains. Many studies on flood mapping have been conducted using one or two dimensional (1D/2D) hydrodynamic models. Some authors affirm that 2D hydraulic models are the state of the art for river flood modeling. They have, however, the disadvantage that their application is constrained by the high requirements for data, hardware and software. 1D models are capable of modeling precisely the flow in main rivers, but are less accurate for modeling over bank flow. The aim of the investigation is to test the accuracy for river floodplain modeling comparing a quasi-2D approach using a 1D model with a full 2D approach. The models were tested for the river Dender in Belgium for three historical flood events.