Research axis 2 (R2): social and biophysical functioning
Actions in detail
Action I: Analyze the impact of the farming method on crop rotation choices in the Lebna watershed
Intissar Ferchichi (INRGREF), Insaf Mekki (INRGREF), Anne Biarnès (IRD/LISAH), Mohamed Elloumi (INRAT) et Abdelaziz Zairi (INRGREF)
| Goals | According to Mekki and Al (2018), several significant factors can explain crop rotation choices in the Lebna watershed. In order to refine our understanding of these choices, we have tried to deepen our knowledge of the arrangements that exist between farmers. In this work, we aim to understand how land dynamics influence the distribution of crops |
| Approach/methodology | Our working hypothesis: the method of farming partly determines the cropping patterns chosen by farmers. Methodology: An analysis of the land dynamics (entering the farm) through semi-directive interviews carried out with the farmers. These interviews relate to: – Characterization and analysis of crop rotation choices from the farmer’s point of view, – The diversity of arrangements, in terms of crop rotation choices, depending on the land status of each plot, – The existing land dynamics (sale, purchase, groups, etc.) |
| Principal results | The spatial distribution of crops in the Lebna watershed is the product of a history of different trajectories of farms. These trajectories are based on two processes: (i) fragmentation and (ii) concentration. The following figure illustrates an example of different trajectories of three farms that originally belong to a private habous (mortmain assets) Read more |
Action II: Concentrated groundwater recharge in the Lebna and Merguellil basins: process and quantification using method hydrogeophysics, isotopic tracers and geo-numerical tools
Fethi LACHAAL (CERTE), Olivier GRÜNBERGER (IRD/LISAH), Radhouane HAMDI (IRD Tunis); Christian LEDUC (IRD/G-EAU); Sylvain MASSUEL (IRD/G-EAU), Nejmeddine OUHICHI (CERTE).
See more
| Goals | Understanding the processes of concentrated groundwater recharge by the Lebna Dam. Study the relationships: surface water/groundwater and Dam/Aquifer. |
| Approach/methodology | In this work, we propose to better understand the groundwater recharge processes, the surface water/groundwater relationships. This, mainly, using i) piezometric monitoring, ii) hydro-geophysical methods, iii) geochemical and isotopic analyzes and iv) geo-numerical tools (FEFLOW and GIS). Fieldwork: Lebna Three campaigns: February, April and May 2018 Mapping of geological outcrops around the Lebna basin; Geophysical investigation; Piezometric study of the water table; Topographic leveling. |
| Principal results | Geological map of the Lebna Lake basin Two geological cross-sections on the flanks of the Lebna dam Geophysical and geometric characterization of the recharge zones downstream of the Lebna Dam Calculation of the average volume of groundwater recharge by the dam over a period of 27 year. |
Actions in detail
Action III – contaminants: occurrence of antibiotics
Olivier GRÜNBERGER (IRD/LISAH), Hanène CHAABANE (INAT), Olfa MAHJOUB, Walid CHMENGUI (INRGREF), Amel JEMAI (INRGREF), Serge CHIRON (IRD/HSM).
see more
| Goals | Assess the contamination of water resources by pharmaceutical products for human and veterinary use in the agricultural environment in Kamech Assess the exposure and the potential health and environmental risks associated, taking into account the agricultural practices in place. |
| Approach/methodology | Physico-chemical characterization of water resources Survey of veterinary products used on farms in place and their use Analysis of some antibiotics and tracer compounds in water |
| Principal results | Identification of veterinary products, in particular antibiotics, used on livestock, their route of administration and their characteristics Bibliographic study in progress on the presence of antibiotics in environmental matrices Identification of water points to be sampled and potential sources of contamination Preparation of a survey on the use and management of veterinary products in the region. |
Action IV: contaminants, soil transfers
Anis Younès (IRD / LISAH), Olivier Grunberger (IRD/ LISAH)
See more
| Goals | Study water and soil pollution by surface contamination. Characterize the hydraulic and contaminant transfer properties of soils. Simulate the transfer of water and contaminants in soils and subsoil, taking into account uncertainties. |
| Approach/methodology | Conducting laboratory experiments on water infiltration and contaminants on a column of undisturbed soil sampled from the study site (Figures 1 and 2). Determination of soil properties by inverse approach by adjusting the results of numerical simulations with the measured data. Calculation of uncertainties on the estimated parameters as well as on the model outputs using Bayesian methods. |
| Principal results | The models used make it possible to accurately simulate the transfer of water and contaminants in soils. The infiltration laboratory experiments allowed a better characterization of the soil properties (lower uncertainty on the parameters) than the percolation-drainage experiments. A dual-medium behavior (mobile-immobile) was observed for contaminant transfer in the studied soil. |
Action V – flux: Evaluation of the SEBS evapotranspiration model using LANDSAT8 in the Lebna catchment”
Rim Zitouna (INRGREF), Hedia Chakroun (ENIT), Frédéric Jacob (IRD/LISAH)
See more
| Goals | The main objective of this action is to explore the use of remote sensing to spatialize the real evapotranspiration of crops in a hilly watershed: case of the Lebna watershed |
| Approach/methodology | Modeling of the ETR by the Surface Energy Balance System model, SEBS, (Su, 2002) integrating inputs from LANDSAT8 time series and meteorological data (2015-2016) Comparison of the results of the simulations of the fluxes of sensible heat and latent heat with observations of the Kamech flux tower Establishment of real evapotranspiration map for the year 2015-2016 |
| Principal results | The confrontation of the SEBS model with the field observations representing a few pixels (figure 1) proves to be consistent for the majority of the simulation dates, even without making topographical corrections. The analysis of the sensible heat simulations by the SEBS model showed that the wind speed has an important influence, hence the importance of taking into account the variability of the wind speed at the basin scale. pouring. The information provided by remote sensing is promising for the simulation of surface energy fluxes and particularly the real evapotranspiration in a hilly environment. |
Master2: Fedi Sebai
Co-supervisors: Hédia Chakroun (ENIT), Rim Zitouna-Chebbi (INRGREF), Fréderic Jacob (IRD)
See more
Setting up agro-climatic stations
December 2017
Setting up agro-climatic stations in Beni Khalled and stations for measuring the actual water consumption of CTA Nabeul orchards (turbulent covariance technique). This action was led by Rim Zitouna in December 2017.