Variability in riparian zone potential and actual evapotranspiration

Micrometeorological and hydrological measurements were made over one growing season using automatic weather stations and weighing lysimeters at several locations within a multiple land-use agricultural catchment in Southern Ontario. This paper compares modelled potential evapotranspiration (PET) and measured actual evapotranspi-5 ration (AET) values obtained from the soil weighing lysimeters, and determines the spatial variability in riparian zone AET in a multiple land-use agricultural watershed in Southern Ontario. Two sites were chosen in two different riparian areas of the watershed , representing the surface conditions dominant in the upper and lower reaches of the basin. 10 The results indicated that AET was higher in the northern end of the basin than in the southern portion of the basin, while the hydrological and energy balance components were similar at both sites. The causes of the different rates are attributed to the surrounding vegetation on adjacent fields and the differing wind regimes.