Climate and terrain factors explaining streamflow response and recession in Australian catchments

摘要

Daily streamflow data were analysed to assess which climate and terrainfactors best explain streamflow response in 183 Australian catchments.Assessed descriptors of catchment response included the parameters of fittedbaseflow models, and baseflow index (BFI), average quick flow and averagebaseflow derived by baseflow separation. The variation in response betweencatchments was compared with indicators of catchment climate, morphology,geology, soils and land use. Spatial coherence in the residual unexplainedvariation was investigated using semi-variogram techniques. A linearreservoir model (one parameter; recession coefficient) produced baseflowestimates as good as those obtained using a non-linear reservoir (twoparameters) and for practical purposes was therefore considered anappropriate balance between simplicity and explanatory performance. About athird (27–34%) of the spatial variation in recession coefficients and BFIwas explained by catchment climate indicators, with another 53% ofvariation being spatially correlated over distances of 100–150 km, probablyindicative of substrate characteristics not captured by the available soiland geology data. The shortest recession half-times occurred in the driestcatchments and were attributed to intermittent occurrence of fast-draining(possibly perched) groundwater. Most (70–84%) of the variation in averagebaseflow and quick flow was explained by rainfall and climatecharacteristics; another 20% of variation was spatially correlated overdistances of 300–700 km, possibly reflecting a combination of terrain andclimate factors. It is concluded that catchment streamflow response can bepredicted quite well on the basis of catchment climate alone. The predictionof baseflow recession response should be improved further if relevantsubstrate properties were identified and measured.