Comparing two approaches for parsimonious vegetation modelling in semiarid regions using satellite data

Abstract

Large portions of Earth's terrestrial surface are arid or semiarid. As in these regions the hydrological cycle and the vegetation dynamics are tightly interconnected, a coupled modelling of these two systems is needed to fully reproduce the ecosystem behaviour and to predict possible responses to climate change. In this paper, the performance of two parsimonious dynamic EVI is reported in literature to be highly correlated with leaf area index so it is compared with modelled LAI mod (r WUE-model =0.45; r LUE-model =0.57). In contrast, NDVI appears highly linked to soil moisture, through the control exerted by this variable on chlorophyll production, and is therefore used to analyze LAI* mod , models' output corrected by plant water-stress (r WUE-model =0.62; r LUE-model =0.59).MODIS LAI and ET are found to be unrealistic in the studied area. The performance of both models in this semiarid region is found to be reasonable.However, the LUE-model presents the advantages of a better performance, the possibility to be used in a wider range of climates and to have been extensively tested in literature.

Calibration of a parsimonious distributed ecohydrological daily model in a data-scarce basin by exclusively using the spatio-temporal variation of NDVI

“…Evidence of aET being a prevalent driver of hydrological records of streamflow and water table depth, i.e., available water resources, has been observed in many studies (Bond et al, 2002;Nyholm et al, 2003;Gribovszki et al, 2008;Conradt et al, 2013). Recently, Tsang et al (2014) showed that adding a better evapotranspiration scheme in a widely used runoff model improves streamflow predictions.…”

“…On the plot scale, Quevedo and Francés (2008) and Pasquato et al (2015) calibrated and validated a parsimonious ecohydrological model using satellite information. More recently, Ruiz-Pérez et al (2016) discussed the applicability of satellite data during the calibration process comparing the results obtained by a parsimonious model calibrated using only satellite data against the results obtained by a complex model calibrated using field measurements on the pixel scale.…”

“…More recently, Ruiz-Pérez et al (2016) discussed the applicability of satellite data during the calibration process comparing the results obtained by a parsimonious model calibrated using only satellite data against the results obtained by a complex model calibrated using field measurements on the pixel scale. Similarly, Quevedo and Francés (2008) and Pasquato et al (2015) used time series of NDVI to validate a parsimonious ecohydrological model named HORAS. On the catchment scale, Immerzeel and Droogers (2008) used satellite-based evapotranspiration in combination with observed streamflow to calibrate the semi-distributed SWAT model.…”

“…Finally, based on previous experiences (Ruiz-Pérez et al, 2016;Pasquato et al, 2015) and in similar climatic conditions, we declined to use other products such as LAI or ET derived from MODIS because these kinds of products are produced by models. And, for example, Ruiz-Pérez et al (2016) found large discrepancies between the LAI provided by satellite and the LAI measured in field.…”

“…However, the LUE can be strongly affected by stress conditions. The key factors contributing to the variation of this efficiency are: soil moisture content, air temperature (Landsberg and Waring, 1997;Sims et al, 2006) and nutrient levels (Gamon et al, 1997;Ollinger et al, 2008). Since this model is designed to be used in water-controlled areas, the nutrient levels are not considered.…”