Y. B. Liu

Analysing the effect of climate changes on streamflow using statistically downscaled GCM scenarios

Abstract This paper discusses the potential impact of climate changes on the streamflow of the Alzette river basin in the Grand‐duchy of Luxembourg. A statistical relationship between observed daily temperature and precipitation to surface and upper‐atmospheric circulation predictor variables from the National Centre for Environmental Prediction (NCEP) reanalysis data is formulated for the period of 1961 to 1990. Future implementation is performed with predictor variables from the coupled HadCM3A2a atmosphere‐ocean general circulation model experiments from the U.K. Meteorological Office, for the periods 2036 to 2065 and 2070 to 2099. To analyse the impact of climate change on the streamflow of the study area, downscaled future local scenarios are applied as input to WetSpa, a spatially distributed hydrological model in which runoff is simulated as a function of rain intensity, soil moisture and terrain characteristics. The results of the hydrologic simulation indicate that there will be a significant increase in the magnitude and frequency of future flooding in the basin.

Assessing the hydrological effects of Landuse changes using distributed hydrological modelling and GIS

Abstract A distributed hydrological modelling and GIS approach was applied for the assessment of landuse changes in the Alzette basin, Grand‐duchy of Luxembourg. The assessment focused on the potential impact of landuse changes on the hydrological processes. Three scenarios were established and investigated. The first scenario considered a realistic increase of urbanisation, while the other scenarios were hypothetical, i.e. forest was converted to agricultural land or the opposite. Comparison of the results for each scenario showed that although the overall changes in the total evapotranspiration and river discharge remained small, that change observed in the different component of the discharge was important. Urbanisation could increase floods by 26% and deforestation increased peak discharges, but to a lesser extent. The afforestation scenario reduced peak flows by as much as 5.3%. Moreover, the afforestation scenario increased soil moisture and base flow.