Watershed modeling using land classifications

A comparison was made between using a lumped hydrological model and using a version of the same model applied successively to different land uses within subbasins. A watershed in the Rocky Mountains of British Columbia was divided into three contributing subbasins, and each of these was further subdivided by land cover classification using Landsat images. A hydrological model was applied separately to each land cover class in each subbasin, and the resulting hydrographs were routed to the subbasin outlet and then through lower subbasins. The final hydrographs were compared to those obtained using the model on the basin as a whole. It was found that using a semidistributed model gives goodness of fit statistics that are better than the lumped basin approach. The land class dependent parameter values found through optimization confirm the physical variations in storages and infiltration rates that would be expected in a mountain basin. The advantage of the semidistributed model is that relating the parameter values to land cover characteristics provides a method of investigating land use changes and allows the model to be more easily transferred to other basins.