Application of the Surface Energy Balance Algorithm for Land (SEBAL) for spatial analysis of evapotranspiration in a commercial oil palm plantation in Jambi Province, Indonesia

Abstract

Evapotranspiration (ET) is one of the climate elements which plays an important role in ecosystem water balance, including in oil palm plantations. Therefore, many mathematical equations and algorithms have been developed and designed to estimate and determine the spatial distribution of evapotranspiration. Remote sensing data are one of the important sources and techniques to estimate spatial variation of various climate elements, including ET. The main objective of this research is to estimate the spatial variation of ET using the SEBAL algorithm and Landsat-8 imagery of a large-scale commercial oil palm plantation, i.e. PT Perkebunan Nusantara VI Batanghari, Jambi Province, Indonesia. The analysis is carried out using Landsat-8 (OLI/TIRS) data and reference meteorological data from a micrometeorology flux tower. We calculated surface radiance, reflectance, albedo, Normalized Difference Vegetation Index (NDVI), emissivity, surface temperature, net radiation, soil heat flux, sensible heat flux, and latent heat flux to derive the hourly and daily evapotranspiration from the study area. Validation of ET from the SEBAL model were performed against ET from aerodynamic measurements from a micrometeorological tower at the same site. Differences in ET within “only oil palm cover” are relatively low and that difference in ET over the entire area of the oil palm plantation is mainly between oil palm vs. open lands, roads, and buildings. The evapotranspiration values of oil palm cover (NDVI 0.45-0.54) were between 2.42 ± 0.36 – 3.36 ± 0.17 mm d-1 . There was no significant difference between ET derived from SEBAL compared to aerodynamic methods (p-value = 0.598; r = 0.75).