Abstract
An accurate assessment of evapotranspiration (ET) is crucially needed at the basin scale for studying the hydrological processes and water balance especially from upstream to downstream. In the mountains, this term is poorly understood because of various challenges, including the vegetation complexity, plant diversity, lack of available data and because the in situ direct measurement of ET is difficult in complex terrain. The main objective of this work was to investigate the potential of a Two-Source-Energy-Balance model (TSEB) driven by the Landsat and MODIS data for estimating ET over a complex mountain region. The complexity is associated with the type of the vegetation canopy as well as the changes in topography. For validating purposes, a large-aperture scintillometer (LAS) was set up over a heterogeneous transect of about 1.4 km to measure sensible (H) and latent heat (LE) fluxes. Additionally, two towers of eddy covariance (EC) systems were installed along the LAS transect. First, the model was tested at the local scale against the EC measurements using multi-scale remote sensing (MODIS and Landsat) inputs at the satellite overpasses. The obtained averaged values of the root mean square error (RMSE) and correlation coefficient (R) were about 72.4 Wm−2 and 0.79 and 82.0 Wm−2 and 0.52 for Landsat and MODIS data, respectively. Secondly, the potential of the TSEB model for evaluating the latent heat fluxes at large scale was investigated by aggregating the derived parameters from both satellites based on the LAS footprint. As for the local scale, the comparison of the latent heat fluxes simulated by TSEB driven by Landsat data performed well against those measured by the LAS (R = 0.69, RMSE = 68.0 Wm−2), while slightly more scattering was observed when MODIS products were used (R = 0.38, RMSE = 99.8 Wm−2). Based on the obtained results, it can be concluded that (1) the TSEB model can be fairly used to estimate the evapotranspiration over the mountain regions; and (2) medium- to high-resolution inputs are a better option than coarse-resolution products for describing this kind of complex terrain.
Highlights
The Mediterranean region is one of the most vulnerable areas to climate variability and change [1], which seriously influences the water resources
This paper evaluated for the first time the performance of two-source energy balance (TSEB) for predicting ET in mountainous agricultural areas using Moderate Sensors Resolution Imaging Spectroradiometer (MODIS) and Landsat input data
It is usually checked that the sum of these fluxes is close to the available energy (Rn − G) by assuming that the energy stored in the canopy is negligible
Summary
The Mediterranean region is one of the most vulnerable areas to climate variability and change [1], which seriously influences the water resources. In Morocco, additional factors such as population growth, urban expansion, tourism development, and more importantly the intensification of agriculture are likely to increase the frequency of water shortages in this region. In several Mediterranean basins, water originates from the mountains and is diverted to irrigated crop areas from upstream to downstream through networks of traditional canals or collected within dams for later use. One of the most important components of water balance in such area is the evapotranspiration (ET). Over mountain regions, this term is still poorly investigated. The reasons are numerous: agriculture in mountainous areas is very heterogeneous (small fields, a large variety of crops including mixed crops) and data are lacking in these poorly gauged areas. There is an urgent need to develop new methodologies for monitoring the evapotranspiration over agricultural mountainous areas
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
