Modelling the impact of anthropogenic modifications to river channels on the course of extreme floods. Case study: August 2002 flood, Blanice River basin, Czechia
Abstract
This paper presents the results of analysis of the impact of anthropogenic modifications to river channels on the course of floods by means of hydraulic modelling. The study is focused on the quantitative analysis of changes of the flow dynamics in the river bed and in the inundation zone due to river network modifications.
The one-dimensional hydraulic model HEC-RAS coupled with GIS is used to simulate the effect of the river channel changes on the course of extreme flood. The analysis is made on the example of the extreme flood in August 2002 on the down course of Blanice River in Czechia.
The results of the simulations proved that the common anthropogenic modifications of river channel have only a minimum impact on the overall course of extreme floods. At the local level, weirs and unsuitably dimensioned bridges have a negative impact on the course of floods.
The simulations also showed a negative impact of extensive complex modifications of the river bed, performed in the lower course of Blanice River in the first half of the 20th century. However, the overall impact of common types of river channel modifications on peak flows and water levels in the culmination is negligible.