Modelling surface energy fluxes over a dehesa (oak savanna) ecosystem using a thermal based two source energy balance model (TSEB) II – integration of remote sensing medium and low spatial resolution satellite images

Authors: ANDREU, A. - Ifapa Centro Alameda Del Obispo; Kustas, William - Bill; POLO, M.J. - Universidad De Cordoba; CARRARA, A. - Universidad De Valencia; GONZALEZ-DUGO, M. - Universidad De Cordoba

Submitted to: Remote Sensing
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/30/2018
Publication Date: 6/15/2018
Citation: Andreu, A., Kustas, W.P., Polo, M., Carrara, A., Gonzalez-Dugo, M. 2018. Modelling surface energy fluxes over a dehesa (oak savanna) ecosystem using a thermal based two source energy balance model (TSEB) II – integration of remote sensing medium and low spatial resolution satellite images. Agricultural Water Management. https://doi.org/10.3390/rs10040567.
DOI: https://doi.org/10.3390/rs10040567

Interpretive Summary: The dehesa is a savanna biome and is also a highly valuable agro-forestry ecosystem, widely distributed over Mediterranean-type climate areas. The dehesa in southern Spain covers nearly 2.5 millions hectares and plays a key role in rural development, based on its productivity and sustainable use for crop production, feed for livestock, wildlife habitat, recreation, etc. The information derived from remote sensing-based models addressing ecosystem water use, at different spatial and temporal scales, has the potential of being used by regulatory agencies and private landowners to support management decisions for sustaining the agricultural productivity and environmental integrity of the dehesa. The remote sensing model based on land surface temperature called the Two-Source Energy Balance (TSEB) model was analyzed over two Spanish dehesa areas integrating multiple satellites for estimating plant water use or evapotranspiration (ET). Model output of ET was successfully mapped using satellite imagery over the region and differences of approximately 1 mm/day with measurements were observed. From these results, it was concluded that the TSEB model is a viable approach to monitor dehesa ecosystem status and vegetation water stress on a regular basis. Both private and public institutions involved in environmental monitoring and agricultural production in the dehesa will benefit from this information being used for improving land management decisions.

Technical Abstract: Dehesas are highly valuable agro-forestry ecosystems/savannas, widely distributed over Mediterranean-type climate areas, which play a key role in rural development, basing their productivity on a sustainable use of multiple resources (crops, livestock, wildlife, etc). The information derived from remote sensing based models addressing ecosystem water consumption, at different scales, can be used by institutions and private landowners to support management decisions. In this study, the Two-Source Energy Balance (TSEB) model was analyzed over two Spanish dehesa areas integrating multiple satellites (MODIS,Landsat) for estimating water use (ET), vegetation ground cover, leaf area and phenology. Instantaneous latent heat (LE) values were derived on a regional scale and compared with eddy covariance tower (ECT) measurements, yielding accurate results (RMSDMODIS Las Majadas 44 W/m^2, Santa Clotilde RMSDMODIS 47 Wm-2 and RMSDLandsat 64 W/m^2). Daily ET [mm] was estimated using daily return interval of MODIS for both study sites and compared with the flux measurements of the ECTs, with RMSD of 1mm day-1 over Las Majadas and 0.99 mm day-1 over Santa Clotilde. Distributed ET over Andalusian dehesa (15% of the region) was successfully mapped using MODIS images, as an approach to monitor the ecosystem status and the vegetation water stress on a regular basis.