SPATIAL VARIATION IN EVAPOTRANSPIRATION AND THE INFLUENCE OF LAND-USE ON CATCHMENT HYDROLOGY

Land use change has a direct effect on hydrology through its link with the evapotranspiration regime. In a large river basin there may be considerable variation in both climate and land use across the region. The potential impact of these variations on the evapotranspiration regime is assessed for the Tyne Basin in NE England, using an approach of physically based modelling. Using a simple hill-slope model, predictions of evapotranspiration are made for various scenarios of land use and climate, representative of those found within the catchment. A catchment model is used to demonstrate how the variations in evapotranspiration might affect the hydrology of a region. Simulations are performed applying various land uses to one upland and one lowland sub-catchment of the Tyne Basin. Results from the simulations show that the same land use change may have a significant effect on the hydrology of the lowland subcatchment, but an insignificant effect on the hydrology of the upland sub-catchment. This highlights the importance of considering the physical attributes of a region in predicting the consequences of land use change.