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International audience; Under climate change conditions, optimizing water resources management in rainfed agricultural production systems requires the reasonable choice of crops. In this context, the adoption of crops diversification is promoted to increase the agricultural production and the added value per cubic meter of rain water (green water) used by crops. Contributing, therefore, to increase agricultural production and to preserve soil and water resources. The objective of this study is: (i) to identify mixed crops within agricultural fields and, (ii) to evaluate the biomass production and the water productivity in the Lebna watershed (Cap-Bon, Tunisia) using remote sensing and field measurements. The study area, covering 210 km 2 , is characterized by the predominant of cereals, legumes and fodder cropping systems. The experiments allowed the quantification of crop evapotranspiration and the observed biomass production at the agricultural field plots. The use of the sentinel images and the observations at different agricultural fields allowed to produce NDVI maps. The results first confirmed a good correlation between biomass production and NDVI values. The exponential relationships showed a values of R 2 greater than 0.7. The use of sentinel images and GIS allowed to compute water productivity from field to watershed scale. The results revealed a considerable spatial variation in water productivity values for different crops. Compared to a single crop, the cereal-legume mixture cropping improved the water productivity. The maximum value with 9.07 kg m −3 is observed for the mixture crops. The lowest value (0.12 to 2.40 kg m −3) was obtained for the cereal crop. These results help to recommend adaptation measures in agricultural production systems to climate change.

Les paysages méditerranéens sont une résultante des conditions hydroclimatiques plus ou moins sévères et des activités humaines séculaires. L’eau, soit par son impact direct, soit par celui de l’usage qu’on en fait, en est le principal architecte. De par l’aridité, les paysages naturels se composent de végétation qui va du chêne aux steppes présahariennes et sont modelées par le relief. Cette région du monde ayant accueilli les civilisations les plus anciennes, celles-ci se sont adaptées aux conditions et contraintes naturelles. En gérant la ressource en eau, elles ont profondément modifié ces paysages, souvent en les embellissant, comme dans le cas des villes-jardins ou des systèmes agro-sylvo-pastoraux, mais parfois en les fragilisant. Dans cette communication, les auteurs s'intéressent particulièrement à la méditerranéenne sèche et présentent des exemples d’aménagements traditionnels du paysage par l’hydraulique. Ils montrent également les défis liés à la dégradation de ces paysages due aux fortes pressions anthropiques, aggravés par un climat qui s’assèche., Le travail de D.R. bénéficie du financement du Projet n° ANR-22-CPJ1-0050-01 dans le cadre d'une Chaire de Professeur Junior IRD en Géoagronomie, {"references":["Alaya, K., Viertmann, W., Waibel, Th. 1993. Les tabias. Imprimerie Arabe de Tunisie, Tunis, Tunisia. 192 pp.: IRA","Albergel, J. (2021, mars 24). Les techniques mises en œuvre en aridoculture [Séances hebdomadaires publiques de l'Académie]. Séance consacrée à l'Aridoculture, Académie d'Agriculture de France. https://www.academie-agriculture.fr/actualites/academie/seance/academie/seance-consacree-laridoculture","Ben Zaied, M. (2019). Tabia [Tunisia] (A. Gavilano & D. Niggli, Éds.). WOCAT SLM Database; https://web.archive.org/web/20230505223134/https://qcat.wocat.net/en/wocat/technologies/view/technologies_1420/. https://qcat.wocat.net/en/wocat/technologies/view/technologies_1420/","Black, J., Maimbo, M., Oduor, A. R., Cherogony, K., & Meerman, R. (2012). Rainwater Harvesting Inventory of Kenya. An overview of techniques, sustainability factor and stakeholders. The World Agroforestry Centre (ICRAF). http://rgdoi.net/10.13140/2.1.2299.5208","Castelli, G., Oliveira, L. A. A., Abdelli, F., Dhaou, M. H., Bresci, E., & Ouessar, M. (2019). Effect of traditional check dams (jessour) on soil and olive trees water status in Tunisia. Science of The Total Environment, 690, 226 236. https://doi.org/10.1016/j.scitotenv.2019.06.514","Critchley, W., & Siegert, K. (1991). Water harvesting. A manual for the design and construction of water harvesting schemes for plant production. Rome (Italy). http://www.fao.org/docrep/U3160E/U3160E00.htm","Deffontaines, J.-P. (1996). Du paysage comme moyen de connaissance de l'activité agricole à l'activité agricole comme moyen de production du paysage. L'agriculteur producteur de paysages. Un point de vue d'agronome. Comptes Rendus de l'Académie d'Agriculture de France, 82, 57 69. http://catalogue.bnf.fr/ark:/12148/cb34410364w","Ennabli, N. (1993). Les aménagements hydrauliques et hydro-agricoles en Tunisie. Institut National Agronomique. Département du Génie Rural des Eaux et des Forêts.","Gao, X., & Giorgi, F. (2008). Increased aridity in the Mediterranean region under greenhouse gas forcing estimated from high resolution simulations with a regional climate model. Global and Planetary Change, 62(3), 195 209. https://doi.org/10.1016/j.gloplacha.2008.02.002","Gomes, N., Touma, J., & Albergel, J. (2008). Water harvesting Techniques, State of the Art, New Researches and Challenges (AquaStress 6th EU Framework Programme for RTD, p. 69) [Project report]. IRD.","King, R., Cori, B., & Vallega, A. (2001). Unity, diversity and the challenge of sustainable development : An introduction to the Mediterranean. In R. King, P. de Mas, & J. Mansvelt Beck (Éds.), Geography, Environment and Development in the Mediterranean (p. 1 17). Sussex Academic Press.","Mbilinyi, B. P., Tumbo, S. D., Mahoo, H. F., Senkondo, E. M., & Hatibu, N. (2005). Indigenous knowledge as decision support tool in rainwater harvesting. Physics and Chemistry of the Earth, Parts A/B/C, 30(11), 792 798. https://doi.org/10.1016/j.pce.2005.08.022","Mekdaschi Studer, R., & Liniger, H. (2013). Water Harvesting—Guidelines to Good Practices. International Fund for Agricultural Development (IFAD). https://www.wocat.net/en/projects-and-countries/projects/water-harvesting-guidelines-good-practice","Mekki, I., Albergel, J., Ben Mechlia, N., & Voltz, M. (2006). Assessment of overland flow variation and blue water production in a farmed semi-arid water harvesting catchment. Physics and Chemistry of the Earth, Parts A/B/C, 31(17), 1048 1061. https://doi.org/10.1016/j.pce.2006.07.003","Mühlematter, D. (2018). Conservation des eaux et des sols suivant la technique des « Jessour » [Tunisia]. WOCAT SLM Database. https://qcat.wocat.net/en/wocat/approaches/view/approaches_4151/","Prinz, D., & Singh, A. (2000). Technological potential for improvements of water harvesting. In World Commission on Dams (Vol. 126, p. 10). https://publikationen.bibliothek.kit.edu/24242000/3247","OSS – Observatoire du Sahara et du Sahel (2017). Meskat. Portail LCD. https://web.archive.org/web/20230524164637/http://projet.oss-online.org/LCD/index.php/groupe-de-pratiques/bonnes-pratiques-d-amenagement-des-sols-et-gestion-de-l-eau/128-meskat","Ridolfi, C. (1827). Sulle colmate di monte. Atti dell'Accademia dei Georgofili, 5, 150 166.","Rizzo, D., Sabbatini, T., & Bonari, E. (2022). A Method to Assess the Fragility of a Terraced System as an Example of Landscape Agronomic Analysis. In D. Rizzo, E. Marraccini, & S. Lardon (Éds.), Landscape Agronomy : Advances and Challenges of a Territorial Approach to Agricultural Issues (1re éd., p. 113 159). Springer International Publishing. https://doi.org/10.1007/978-3-031-05263-7_4","Taamallah, H. (2010). Gestion durable des terres en Tunisie : Bonnes pratiques agricoles (LADA Land Degradation Assessment in Drylands). FAO.","Tarolli, P., Preti, F., & Romano, N. (2014). Terraced landscapes : From an old best practice to a potential hazard for soil degradation due to land abandonment. Anthropocene. https://doi.org/10.1016/j.ancene.2014.03.002","Wang, W., Straffelini, E., Pijl, A., & Tarolli, P. (2022). Sustainable water resource management in steep-slope agriculture. Geography and Sustainability, 3(3), 214‑219. https://doi.org/10.1016/j.geosus.2022.07.001","Waelti, C., & Spuhler, D. (2019, avril 4). Micro Basins. Sustainable Sanitation and Water Management Toolbox. https://web.archive.org/web/20230509084043/https://sswm.info/ar/sswm-solutions-bop-markets/improving-water-and-sanitation-services-provided-public-institutions-0/micro-basins"]}

Freshwater - a fragile resource - is essential for life, development, and the environment. The Senegal River is a strategic region for the socio-economic development of these countries. The Senegal River's water management in time and space is possible thanks to the existing and future hydropower reservoirs. Hydropower is the world's largest and most widely used renewable energy source. In the future, hydropower is expected to be profoundly impacted due to the changes in river flow caused by climate change. This study examined the impact of climate change on the hydropower potential in the Senegal River basin for the periods P2 (2035-2065) and P3 (2065-2095) compared to P1 (1984-2014) under ssp 126 and ssp 370. We found that for P2, compared to P1, an increase of 6% in the annual flow would lead to an increase of 3% in annual hydropower generation for the ssp 126. A decrease of -1% in annual flow would reduce -0.7% in annual hydropower generation for the ssp 370. For P3 compared to P1, a reduction of annual flow by -6% and -13% would cause a decrease of -8% and -14% in annual hydropower, respectively, for ssp 126 and ssp 370. The planned reservoirs would increase the surface water storage, but it would cause a loss of -11% of the hydropower of the existing reservoir. Therefore, it is crucial to develop new adaptation techniques by combining hydro, solar and wind energy to mitigate the effects of climate change., The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)

Research and innovation (R&I) feature high in both the African Union’s and the European Union’s agenda. While the African Union “Science, Technology and Innovation Strategy for Africa 2024” (STISA-2024) places science, technology and innovation at the epicentre of Africa’s socio-economic development and growth, European investments in R&I are seen as a means to help Europe to compete globally and improve the daily lives of people.Under the AU-EU partnership, both continents have also confirmed their commitment to strengthen R&I collaboration and partnership to address common or complementary society challenges. The EU’s main tool to support such collaborative efforts is the Horizon Europe Framework programme which will run over the period 2021-2027. This programme, which builds on the previous R&I framework programmes, also integrates new instruments such as “missions” and “European partnerships” which aim at finding new R&I research funding instruments and innovative ways of collaboration involving all stakeholders (from consumers to industry) as partners. In this context, it will be important to understand how new joint research and innovation (R&I) mechanisms can support research and development activities.Through an online survey, African and European partners were invited to share their experience with LEAPAgri and the lessons learned in order to develop suggestions for a strategy that would promote the partnership forward by evaluating and identifying mechanisms to sustain collaboration and innovation in the FNSSA field. All 24 partners of the LEAP-Agri consortium were asked to share their opinion which is highly valuable since,apart from being partners in the project, most of them also represent national agencies or funding bodies with solid experience in financing FNSSA's R&I activities. The participants shared their own experience in the field, either through LEAP-Agri or other similar co-funded projects such as ERAFRICA. On this basis, they provided inputs regarding the important aspects of collaboration mechanism and ideas on alternative instruments capable of taking the FNSSA R&I partnership to the next level., La recherche et l'innovation (R&I) figurent en bonne place dans l'agenda de l'Union africaine et de l'Union européenne. Alors que la "Stratégie pour la science, la technologie et l'innovation en Afrique 2024" (STISA-2024) de l'Union africaine place la science, la technologie et l'innovation à l'épicentre du développement socio-économique et de la croissance de l'Afrique, les investissements européens dans la R&I sont considérés comme un moyen d'aider l'Europe à être compétitive au niveau mondial et à améliorer la vie quotidienne des gens.Dans le cadre du partenariat UA-UE, les deux continents ont également confirmé leur engagement à renforcer la collaboration et le partenariat en matière de R&I afin de relever des défis de société communs ou complémentaires. Le principal outil de l'UE pour soutenir ces efforts de collaboration est le programme-cadre Horizon Europe, qui s'étendra sur la période 2021-2027. Ce programme, qui s'appuie sur les précédents programmes-cadres de R&I, intègre également de nouveaux instruments tels que les "missions" et les "partenariats européens" qui visent à trouver de nouveaux instruments de financement de la recherche en R&I et des modes de collaboration innovants impliquant toutes les parties prenantes (des consommateurs à l'industrie) en tant que partenaires. Dans ce contexte, il est important de comprendre comment les nouveaux mécanismes conjoints de recherche et d'innovation (R&I) peuvent soutenir les activités de recherche et de développement.Par le biais d'une enquête en ligne, les partenaires africains et européens du programme LEAP-Agri ont été invités à partager leur expérience et les leçons apprises afin de développer des suggestions pour une stratégie qui ferait avancer le partenariat en évaluant et en identifiant les mécanismes permettant de soutenir la collaboration et l'innovation dans le domaine de la Sécurité Alimentaire, Nutritionnel et l'Agriculture durable (SANAD). Les 24 partenaires du consortium LEAP-Agri ont été invités à partager leur opinion, ce qui est très précieux car, en plus d'être des partenaires du projet, la plupart d'entre eux représentent également des agences nationales ou des organismes de financement ayant une solide expérience du financement des activités de R&I de la SANAD. Les participants ont partagé leur propre expérience sur le terrain, que ce soit dans le cadre de LEAP-Agri ou d'autres projets cofinancés similaires tels qu'ERAFRICA. Sur cette base, ils ont apporté des contributions concernant les aspects importants du mécanisme de collaboration et des idées sur des instruments alternatifs capables de faire passer le partenariat R&I de la SANAD à un niveau supérieur.

International audience; Rainfed agriculture provides several benefits such as food and water resource production. However, it is becoming increasingly exposed to climate and anthropogenic changes. Which can increase the threats on crop and water resource production. To investigate the future anthropogenic and climate change impacts on crops production and water resources' preservation it is essential to ensure that models can appropriately simulate complex agro-hydrological processes in rainfed watershed. The objective of this study was to perform a multi-criteria evaluation of the SWAT model to understand and simulate agro-hydrological processes of the rainfed semi-arid watershed in Tunisia. In this study, 20 years (1995-2015) of hydro-meteorological and vegetation data from the Mediterranean Observatory for Rural Environment and Water (OMERE) have been used. Monitoring includes daily hydrometric data, soil moisture on multiple profiles, actual evapotranspiration, and aboveground biomass. The study focuses on the Lebna watershed (210 km 2) northeast of Tunisia marked by the predominance of rainfed wheat, legumes and fodder crops. The SWAT model is implemented by adopting a three-step calibration procedure. A first step was devoted to sensitivity analysis using the SWAT_CUP tool for model parameters. The calibration of the discharge at the level of the watershed, followed by a simultaneous calibration of the discharge and the evapotranspiration in order to test the effect on the model performances. The third step is to specify the management operations in the model and to assess the impacts on the results. The simulation was performed for the years 1995 to 2015, of which the first four years were considered for warming up the model. The analysis of the results of the model is carried out based on the discretization of the watershed according to a parcel division into more than 600 distinct units. According to the results, the model performance was improved by the multiparameter and multivariable calibration in terms of NSE. The ongoing analysis will concentrate on implementing reservoirs to have a better understanding of the possible impacts on the simulation.

International audience

International audience

The hydrology of the Mediterranean region is affected by global changes such as climate and land use changes. In rural areas, changes in farming practices and landscape management can be the main drivers of changes in water cycles and in matter transport associated with hydrological fluxes, such as contaminants and sediments. The process underlying these changes can be slow, such as in land use or contaminant dynamics, or infrequent over time, such as erosion. Understanding these processes and their relationship requires long-term observations to capture slow dynamics or infrequent events. In this context, we present the Mediterranean agro-hydrological observatory OMERE (Mediterranean observatory of the rural environment and water) by explaining the observation strategy and by emphasizing how this strategy and associated research have contributed to a better understanding of the impact of agricultural and land management on mass flows in Mediterranean farmed headwater catchments.The OMERE observatory is made up of two agricultural catchments, one in the north of Tunisia and the other in the south of France, accounting for for the diversity of agricultural and ecosystem situations in hilly Mediterranean areas. The OMERE observatory belongs to the French national network OZCAR, dedicated to the observation of the critical zone. The observation strategy is motivated by monitoring the flow of water, sediments and contaminants and hydrological and climatic variables at different spatial scales from cultivated plots and landscape elements to the catchment scale. These measurements were made with fine temporal resolution on a long-term scale and examining land use, agricultural practices and soil surface characteristics. The long-term observation strategy aims to support multidisciplinary integrative research to elucidate the conditions that improve soil and water management and the provision of ecosystem services in the Mediterranean context of rain-fed agriculture. The observatory addressed three scientific questions: (i) better understand water flows, erosion and contaminants, in particular pesticides, and their natural and anthropogenic factors in the short and long term; (ii) analyze the overall effects of agriculture and land management on mass flows at different scales, from the plot to the watershed or the landscape; and (iii) develop new scenarios for sustainable agricultural management and better delivery of ecosystem services. Some of the scientific progresses driven by the questions drawn from the OMERE observatory are presented.Voltz, M., and A. Albergel. 2002. OMERE: Observatoire Méditerranéen de l’Environnement Rural et de l’Eau- Impact des actions anthropiques sur les transferts de masse dans les hydrosystèmes méditerranéens ruraux. Proposition d’Observatoire de Recherche en Environnement. Minist. Français Rech., ParisMolénat, J., Raclot, D., Zitouna R., ...., Albergel, J., and Voltz M., 2018, OMERE: A Long-Term Observatory of Soil and Water Resources, in Interaction with Agricultural and Land Management in Mediterranean Hilly Catchments, Vadose Zone J., 17:180086. doi:10.2136/vzj2018.04.0086

International audience; This study (i) presents a coupled vegetation-soil model adapted to perennial C4 seasonally flooded semi-arid grasslands; and (ii) applies the model to evaluate changes in the annual productivity of the grasslands of the Tana River Delta, Kenya, under changing flooding conditions. Main plant growth processes are modelled within coupled plant carbon balance and soil water budget modules: photosynthesis, allocation of photosynthates, respiration, translocation of root phytomass to aerial phytomass, senescence and litter production. Aerial phytomass can also be subtracted from the system, to simulate grazing or cutting. New features concern the inclusion of effects of floods on energy conversion efficiency, photosynthate allocation, senescence and litter production. The vegetation model, composed of four phytomass compartments (leaves, stems, roots, aerial dead matter), simulates three main growth phases related to flooding: floods, a post-flood phase and a non-flooded phase. It was designed to be used with limited climatic data. Data collected during a 14-month experiment (2010-2012) in the Tana River Delta, Kenya, in which different irrigation and cutting treatments and flood events were recorded, were used for calibration and validation purposes. Fourteen parameters, selected through a sensitivity analysis, were calibrated on half of these treatments. Uncertainty in parameter estimation was expressed through a stochastic ensemble of simulations. The remaining independent data were used for model validation. Overall, the model predictions are in good agreement with the experimental data. This model can be used to assess the impact of rain variability, grazing or flooding patterns on the annual primary productivity of Sub-Saharan floodplain grasslands composed mainly of Echinochloa stagnina (Retz) P. Beauv. In particular, simulations for the Tana River Delta suggest that past changes in the hydrological regime of the river, as well as future changes due to the construction of hydroelectric infrastructure, have led and will certainly lead to an important decrease of the floodplain grassland productivity. As local and regional livestock keeping activities rely heavily on the dry seasons' grazing resources available within the wetland, future development plans should seriously consider the negative effects of these changes on local activities and livelihoods.

L’idée d’un livre portant sur la coopération entre l’Afrique et l’Europe en matière de recherche et d’innovation est née en 2014, lors d’une discussion entre Gerard Ralphs et Andy Cherry. James Haselip et Isabella E. Wagner ont rejoint l’équipe peu après et ont assumé des rôles centraux dans le processus éditorial. Dès le début de la rédaction et avec l’encouragement de la commission de l’Union Africaine, une version en langue française a été envisagée. Les éditions de l’IRD en ont accepté l’...

Les relations scientifiques et technologiques entre l'Afrique et l'Europe ont une histoire longue, dynamique et parfois en dents de scie, qui traduit une certaine complexité en termes d'intérêts et de stratégies aux niveaux national, régional et international. Ce livre traite de la coopération dans le domaine de la recherche appliquée, en quête de solutions face aux défis sociétaux communs. Ainsi aborde-t-il quatre défis majeurs. Premièrement, fournir un aperçu compréhensible du paysage mondial des politiques de recherche et d'innovation dans lequel le partenariat stratégique Afrique-Europe fonctionne actuellement. Deuxièmement, procéder à une analyse critique des divers réseaux et organisations qui soutiennent, permettent et renforcent la coopération bi-régionale en matière de sciences, technologies et innovation [STI]. Troisièmement, éclairer les résultats et l'impact de certaines initiatives réelles des entreprises opérant dans le domaine de la STI. Quatrièmement, présenter une série de leçons claires susceptibles d'appuyer les futurs efforts de coopération entre l'Afrique et l'Europe en matière de STI.