Assessment of actual evapotranspiration over a semiarid heterogeneous land surface by means of coupled low-resolution remote sensing data with an energy balance model : comparison to extra-large aperture scintillometer measurements - IRD - Institut de recherche pour le développement Accéder directement au contenu
Article Dans Une Revue Hydrology and Earth System Sciences Année : 2018

Assessment of actual evapotranspiration over a semiarid heterogeneous land surface by means of coupled low-resolution remote sensing data with an energy balance model : comparison to extra-large aperture scintillometer measurements

Résumé

In semiarid areas, agricultural production is restricted by water availability; hence, efficient agricultural water management is a major issue. The design of tools providing regional estimates of evapotranspiration (ET), one of the most relevant water balance fluxes, may help the sustainable management of water resources. Remote sensing provides periodic data about actual vegetation temporal dynamics (through the normalized difference vegetation index, NDVI) and water availability under water stress (through the surface temperature T surf), which are crucial factors controlling ET. In this study, spatially distributed estimates of ET (or its energy equivalent, the latent heat flux LE) in the Kairouan plain (central Tunisia) were computed by applying the Soil Plant Atmosphere and Remote Sensing Evapotranspira-tion (SPARSE) model fed by low-resolution remote sensing data (Terra and Aqua MODIS). The work's goal was to assess the operational use of the SPARSE model and the accuracy of the modeled (i) sensible heat flux (H) and (ii) daily ET over a heterogeneous semiarid landscape with complex land cover (i.e., trees, winter cereals, summer vegetables). SPARSE was run to compute instantaneous estimates of H and LE fluxes at the satellite overpass times. The good correspondence (R 2 = 0.60 and 0.63 and RMSE = 57.89 and 53.85 W m −2 for Terra and Aqua, respectively) between instantaneous H estimates and large aperture scintillome-ter (XLAS) H measurements along a path length of 4 km over the study area showed that the SPARSE model presents satisfactory accuracy. Results showed that, despite the fairly large scatter, the instantaneous LE can be suitably estimated at large scales (RMSE = 47.20 and 43.20 W m −2 for Terra and Aqua, respectively, and R 2 = 0.55 for both satellites). Additionally, water stress was investigated by comparing modeled (SPARSE) and observed (XLAS) water stress values ; we found that most points were located within a 0.2 confidence interval, thus the general tendencies are well reproduced. Even though extrapolation of instantaneous latent heat flux values to daily totals was less obvious, daily ET estimates are deemed acceptable.
Fichier principal
Vignette du fichier
Saadi_HESS2018.pdf (3.97 Mo) Télécharger le fichier
Origine : Fichiers éditeurs autorisés sur une archive ouverte
Loading...

Dates et versions

ird-01762227 , version 1 (09-04-2018)

Identifiants

Citer

Sameh Saadi, Gilles Boulet, Malik Bahir, Aurore Brut, Emilie Delogu, et al.. Assessment of actual evapotranspiration over a semiarid heterogeneous land surface by means of coupled low-resolution remote sensing data with an energy balance model : comparison to extra-large aperture scintillometer measurements. Hydrology and Earth System Sciences, 2018, 22 (4), pp.2187 - 2209. ⟨10.5194/hess-22-2187-2018⟩. ⟨ird-01762227⟩
567 Consultations
522 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More