Calibration of a water resources simulation model by means of spatially disaggregated runoff data

This paper describes a calibration procedure of a water resources simulation model based on the geomorphologic instantaneous unit hydrograph (giuh). The simulation model will be used as a tool in the planning phase of land consolidatation projects. In order to improve water management in rural catchments situated in the land consolidation area, different alternatives concerning structural measures (such as location and capacity of storage basins) need to be investigated. The selection between alternatives is based on, among other things, environmental impact considerations. One of the main problems in hydrological simulation for small (< 50 km²) rural catchments in Flanders (Belgium) is the lack of discharge measurements. Recently, the problem of prediction for ungauged river basins has been studied through physically meaningful stochastic theories such as the giuh. This giuh-technique is used in the case study presented in the paper. The rainfall-runoff relationship is identified using historical discharge data recorded at a downstream gauging station. The only unknown parameter in the giuh is a parameter representative for the velocity of the water particles in the channel network. This velocity is assumed to be constant throughout the network. Based on this assumption it is possible to calibrate the giuh model for subcatchments upstream from the gauging station. Once the dynamic hydrologic behaviour of the catchment is determined, a flood routing model which can take into account different interior boundary conditions is developed. This simulation model is used to quantify the effects of structural measures such as the implementation of storage basins.