Abstract:
In this study, the Surface Energy Balance Algorithm for Land (SEBAL) approach was applied for the estimation of surface energy fluxes over different land use land cover using remotely sensed data over Akure, the study area. The objectives of this work includes generation of Land Use Land Cover map of Akure, determination of the variation of surface energy fluxes over different Land Use Land Cover and evaluation of the reliability of the surface energy balance algorithm using ground station data. The Land Use Land Cover analysis from 1984 – 2014 revealed increase in the built-up area by 9,710 hectares while the forested area decreased by 7,350 hectares. From the surface energy fluxes maps for 1984, built up area had the lowest net radiation with a mean values of 472.56 W/m2, while the highest net radiation was over the forested area (mean value of 528.93 W/m2). For sensible heat flux, the highest values were over the built up area with a mean of 245.5 W/m2 and the lowest values over the forested area (mean value of 160.5 W/m2). Latent heat flux was highest over the forested area with a mean value of 304.1 W/m2 while the built up area had the lowest latent heat flux (mean value of 164.3 W/m2). Similar distribution was observed in the other years of study. This shows that the composition of surface energy fluxes differ with the characteristics of the surfaces, which therefore indicates that the available energy over vegetative and less vegetative area is partitioned according to the conditions of the underlying surface. Evaluating the performance of SEBAL, the correlation coefficient of net radiation was 0.83, soil heat flux 0.23, sensible het flux 0.9 and latent heat flux 0.96. Further error analysis showed poor estimation of soil heat flux. In conclusion, SEBAL model can be applied for the estimation of surface energy fluxes in areas of sparse ground station data and can also reveal the spatial variation of the energy fluxes.
