Assessment of overland flow variation and blue water production in a farmed semi-arid water harvesting catchment

Mekki, Insaf; Albergel, Jean; Mechlia, N. Ben; Voltz, Marc

doi:10.1016/j.pce.2006.07.003

Cited by 27 publications

(33 citation statements)

References 22 publications

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“…The crop cycles range from autumn to summer (Fig. 2), and crop scheduling differs from one crop to another (Mekki et al, 2006). Cereals may be stereotypically rotated with legumes or spices to capture the benefits of nitrogen fixation (in the case of legumes) and/or to break pest or weed cycles.…”

Section: Impact Of Farmland Fragmentation On Rainfed Crop Allocation Inmentioning

confidence: 99%

Impact of farmland fragmentation on rainfed crop allocation in Mediterranean landscapes: A case study of the Lebna watershed in Cap Bon, Tunisia

et al. 2018

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Section: Impact Of Farmland Fragmentation On Rainfed Crop Allocation Inmentioning

confidence: 99%

Impact of farmland fragmentation on rainfed crop allocation in Mediterranean landscapes: A case study of the Lebna watershed in Cap Bon, Tunisia

et al. 2018

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“…The slopes range between 0 % and 30 %, the quartiles being 6%, 11% and 18%. The soils have sandy-loam textures, with depths ranging from 0 to 2 m according to the location within the watershed and to the local topography [17]. Most of the crops were rain-fed.…”

Section: Site Descriptionmentioning

confidence: 99%

“…They experience intensification of rainfed agriculture, since topographical conditions permit the mobilization of water resources [17,18,19,20]. They depict strong spatial heterogeneities, because of family farming that induces very small fields.…”

Section: Introductionmentioning

confidence: 99%

Observing Actual Evapotranspiration within a Hilly Watershed: Case Study of the Kamech Site, Cap Bon Peninsula, Tunisia

Zitouna-Chebbi

Prévot

Chakhar

et al. 2017

Proceedings of the 2nd International Electronic Conference on Atmospheric Sciences

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There is a strong need for long term observations of land surface fluxes, especially the latent heat flux (λE), or actual evapotranspiration (ETa), a key component of both the surface energy balance and the hydrological cycle. The eddy covariance (EC) method is widely used to provide measurements of land surface fluxes. However, missing data are inherent to EC measurements and several gap-filling methods have been proposed. Nevertheless, observing ETa by EC and testing gap-filling methods in hilly watersheds received little attention. This study aimed at obtaining continuous ETa time series from EC measurements collected within a small hilly watershed, which implied adapting gap-filling techniques to these particular conditions. The experiment took place within the agricultural watershed Kamech (Northeast Tunisia) which belongs to the OMERE environmental observatory. A 9.6-meter-high EC flux tower was installed in the center of the 2.45 km 2 area watershed. Sensible and latent heat fluxes data collected from 2010 to 2013 were quality controlled. The software REddyProc was used to gap-fill the fluxes at hourly timescale. To account for the combined effects of wind direction and topography, REddyProc was applied after separating the two dominant wind directions, which notably improved the estimated fluxes. Aggregating the hourly λE estimates at daily and monthly timescales allowed analyzing the temporal variability of ETa over the seasons and between years.

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“…This test area is a 6.67 km² area that is centered on the Kamech catchment, which contained a high percentage of bare soils during image acquisition and exhibited contrasting soil patterns. The Kamech experimental catchment belongs to a long-term environmental research observatory called OMERE (Mediterranean observatory of water and rural environment) which aims to study the anthropogenic impacts on water and sediment budgets at catchment scale (e.g., Mekki et al, 2006;Raclot and Albergel, 2006). The Kamech catchment is characterized by strong variations in soil patterns on a small scale, with a close succession of clay-rich areas and clay-poor areas, oriented northwest/southeast, corresponding to marl and sandstone outcrops, respectively.…”

Section: Clay Predicted Mapsmentioning

confidence: 99%

Using Legacy Soil Data for Standardizing Predictions of Topsoil Clay Content Obtained From Vnir/Swir Hyperspectral Airborne Images

Gomez

Gholizadeh

Borůvka

et al. 2015

Int. Arch. Photogramm. Remote Sens. Spatial Inf. Sci.

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ABSTRACT:Mapping of topsoil properties using Visible, Near-Infrared and Short Wave Infrared (VNIR/SWIR) hyperspectral imagery requires large sets of ground measurements for calibrating the models that estimate soil properties. To avoid collecting such expensive data, we proposed a procedure including two steps that involves only legacy soil data that were collected over and/or around the study site: 1) estimation of a soil property using a spectral index of the literature and 2) standardisation of the estimated soil property using legacy soil data. This approach was tested for mapping clay contents in a Mediterranean region in which VNIR/SWIR AISA-DUAL hyperspectral airborne data were acquired. The spectral index was the one proposed by Levin et al (2007) using the spectral bands at 2209, 2133 and 2225 nm. Two legacy soil databases were tested as inputs of the procedure: the Focused-Legacy database composed of 67 soil samples collected in 2000 over the study area, and the No-Focused-Legacy database composed of 64 soil samples collected between 1973 and 1979 around but outside of the study area. The results were compared with those obtained from 120 soil samples collected over the study area during the hyperspectral airborne data acquisition, which were considered as a reference.Our results showed that: 1) the spectral index with no further standardisation offered predictions with high accuracy in term of coefficient of correlation r (0.71), but also high bias (-414 g/kg) and SEP (439 g/kg), 2) the standardisation using both legacy soil databases allowed an increase of accuracy (r = 0.76) and a reduction of bias and SEP and 3) a better standardisation was obtained by using the Focused-Legacy database rather than the No-Focused-Legacy database. Finally, the clay predicted map obtained with standardisation using the Focused-Legacy database showed pedologically-significant soil spatial structures with clear short-scale variations of topsoil clay contents in specific areas.This study, associated with the coming availability of a next generation of hyperspectral VNIR/SWIR satellite data for the entire globe, paves the way for inexpensive methods for delivering high resolution soil properties maps.

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Assessment of overland flow variation and blue water production in a farmed semi-arid water harvesting catchment

Cited by 27 publications

References 22 publications

Impact of farmland fragmentation on rainfed crop allocation in Mediterranean landscapes: A case study of the Lebna watershed in Cap Bon, Tunisia

Impact of farmland fragmentation on rainfed crop allocation in Mediterranean landscapes: A case study of the Lebna watershed in Cap Bon, Tunisia

Observing Actual Evapotranspiration within a Hilly Watershed: Case Study of the Kamech Site, Cap Bon Peninsula, Tunisia

Using Legacy Soil Data for Standardizing Predictions of Topsoil Clay Content Obtained From Vnir/Swir Hyperspectral Airborne Images

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