The impact of floodplain land use on flood wave propagation

Abstract

Due to their retention capacity, extensive flat floodplains have a significant impact on the propagation and transformation of flood waves. The conveyance and retention capacity of an area is significantly influenced by land use. The paper presents results of a hydraulic analysis of the impact of land use on the run-off regime in a retention area and consequently on flood wave propagation. The land use of the retention area was simulated by hydraulic roughness. The simulations were performed for flood waves with different values of peak discharge and with two lengths of duration. A spectrum of flood waves in which the retention areas have significant impact on the propagation was considered. To isolate the impact of topographical characteristics of riparian and retention areas on the communication of water between the channel and retention area, as well as on the formation of parallel streams in the area, a theoretical modelling area with simplified geometry was used in the first phase. Conclusions based on the results of the first-phase simulations were tested on a practical case of the plain Krsko–Brežisko polje, where data from field measurements as well as data from the physical model were used in the numerical calibration of the model.