Parameter recalculation for a rainfall-runoff model with a focus on runoff curve numbers

One of the fundamental issues of hydrology is determination of total runoff volume from rainfall. The mutual relationship of these quantities can be experimentally determined by measuring rainfall and runoff. Rainfall-runoff models describe natural relations on the basis of variables determining physio-geographical conditions of a territorial unit as well as hydraulic properties of the respective river network. In the proposed paper, we focused on parameter recalculation of a rainfall-runoff model with focusing on runoff curve numbers (CN). The objective of this study was to update the data (CN) in the old modelling structures within the FLOREON+ (FLOods REcognition on the Net – Study Area) system and replace them with the new ones. The parameters of runoff CN were estimated according to available GIS layers primarily related to the existing soil conditions and land use. In the first phase, the calculation procedure was prepared for the smaller Porubka and Lubina basins, and then it was applied to the whole basin area. The results showed that the new runoff CN recalculation procedure resulted in reduction of the simulated runoff (peak discharge, volume) in the Odra River sub-basins, which also led to approximation to the real measured runoff in the Ostrava-Svinov profile. The derived method is applicable to other basins as well.

Highlights for public administration, management and planning:

• Runoff volumes resulting from rainfall significantly contribute to risk processes, such as soil erosion and floods.

• The partially automated procedure for rainfall-runoff estimation is preseted, based on data for soil conditions and land cover.

• Derivation is based on the original principles determined by the US Soil Conservation Service and can be applied to any river basin in the area of the Czech Republic.

• In the future, the proposed methodology will be adapted to run within the ArcMap application.