Catchment wide hydrology using radar rainfall

Abstract

Accurate flood modeling is reliant on a well validated hydrologic model balanced with hydraulic models capable of representing realistic flood flows as a result of rainfall over the catchment. However nearly all calibration/validation models of real recorded events are reliant on only extremely sparse recorded rainfall data from representative rain gauges. However for several years now radar data has been available but is scarcely used. This papers reports on the ongoing development of the ANUGA model with the addition of a (X,Y,t) spatial grid format which allows grided rainfall time series to be used as input. Using radar rainfall data provides for a far more variable and likely realistic representation of spatial and temporally varying rainfall. Hence the resulting runoff response should also be far more realistic. Testing using radar rainfall calibrated against rain gauges is showing very beneficial outcomes of this approach over simply adopting rain gauge data and traditional distribution methods such as Thiessen weighting. In addition the ability of this model to apply the rainfall directly to 3D terrain over the entire catchment to resolve the hydraulics provides for a very robust and stream lined approach to complex catchment hydrology and hydraulics. This methodology is being applied to model all catchments contributing to flow in the ACT, and is also being applied to large catchment in Germany.