HAL-BRGM, les publications scientifiques en libre accès du BRGM
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Towards multiservice irrigation for an agroecological future
No full textInternational audienceAgroecology and water management knowledge spheres have long been disconnected. This paper advocates bridging this divide to boost sustainable food production. We stress that a paradigm shift is needed so that irrigation will no longer be viewed merely as a technical productivity support tool. A multiservice irrigation concept is proposed whereby irrigation is planned and applied to enhance ecosystem functions essential for sustainable food production
Étude de l'impact de l'irrigation sur les services et dis services écosystémiques fournis par les plantes de service dans des systèmes en transition vers l'agriculture de conservation
No full textMémoire de fin d’études pour l’obtention du diplôme d’Ingénieur Agronome spécialité Science et Génie de l’EnvironnementMasterThis master’s thesis focuses on conservation agriculture and sustainable water management, in a context of climate change where water is becoming increasingly scarce. The main objective is to compare the impact of different irrigation regimes on the ecosystem services (ES) and disservices (EDS) provided by cover crops. These service plants play a key role in soil fertility, protection, and resilience, but their effectiveness strongly depends on their development, and thus on water availability.The experiment was conducted at two contrasting INRAE sites: Toulouse-Auzeville (oceanic climate) and Montpellier-Lavalette (Mediterranean dry climate). Three irrigation regimes were tested (rainfed, single irrigation after sowing, and unlimited irrigation) on summer cover crops (sorghum alone or in mixture with cowpea and sunflower), followed by winter cover crops (faba bean) and a cash crop (grain sorghum).The study assessed crop growth and biomass, as well as several ES and EDS: nitrogen and nutrient restitution, carbon storage, weed regulation, soil structure, and moisture retention. Results show that irrigation significantly influences biomass production and thus ecosystem services, especially under dry Mediterranean conditions, with biomass nearly doubling at Lavalette under unlimited irrigation. However, short-term effects on the cash crop were limited.These findings highlight that irrigation can enhance the ES provided by cover crops but may also generate EDS linked to water consumption. It should therefore be considered as a trade-off, adapted to climate conditions and agronomic objectives, in order to balance agricultural performance with the sustainability of agroecosystems.Ce mémoire de fin d’études porte sur l’agriculture de conservation et la gestion durable de l’eau, dans un contexte de changement climatique où cette ressource devient limitée. L’objectif principal est de comparer l’impact de différentes modalités d’irrigation sur les services écosystémiques (SE) et les disservices écosystémiques (DSE) fournis par les couverts d’interculture. Ces plantes de service jouent un rôle clé dans la fertilité, la protection et la résilience des sols, mais leur performance dépend fortement de leur développement, donc de la disponibilité en eau.L’expérimentation a été conduite sur deux sites de l’INRAE contrastés par leur climat : Toulouse-Auzeville (océanique altéré) et Montpellier-Lavalette (méditerranéen sec). Trois modalités hydriques ont été testées (pluvial, irrigation de levée, irrigation sans restriction) sur des couverts d’été (sorgho seul ou en mélange avec niébé et tournesol), suivis par des couverts d’hiver (féverole) et une culture de rente (sorgho grain).L’étude a porté sur la croissance et la biomasse des couverts, ainsi que sur plusieurs SE et DSE : restitution en azote et éléments minéraux, stockage de carbone, régulation des adventices, structuration et humidité du sol. Les résultats montrent que l’irrigation influence fortement la biomasse et donc les services rendus, surtout en climat sec. En revanche, l’impact sur la culture principale reste limité à court terme.Ces travaux montrent que l’irrigation peut renforcer les SE fournis par les couverts, mais aussi générer des DSE liés à la consommation d’eau. Elle doit donc être pensée comme un compromis, ajusté au climat et aux objectifs agronomiques, afin de concilier performance agricole et durabilité des agroécosystèmes
Microclimate, Soil and Plant Dataset From a Mediterranean Urban Canyon With Irrigated Planters
No full textInternational audienceDataset obtained from a fully instrumented experimental urban street canyon, located on a research site in Montpellier (France, Mediterranean climate) and monitored between 21 July 2023 and 31 July 2024. This east–west canyon consists of two parallel concrete walls (height 2.3 m, length 12 m, width 5 m). Three nearly adjacent planters (height 0.9 m, length 2.3 m, width 0.8 m) are aligned along its inner north wall and contain climbing plants of the Lonicera japonica species. Three other nearly adjacent planters (height 0.9 m, length 2.3 m, width 1.1 m) are aligned along its inner south wall and contain shrub plants of the Abelia grandiflora species. Each planter includes 11 sensors to measure soil temperature, water content and matric potential, collecting data every 10 min. Drip irrigation was used and each series of planters received identical irrigation amounts. The irrigation strategy changed several times, to monitor the impacts of irrigation on the overall water balance of the soil–plant–atmosphere system, especially on the local microclimatic variables. A dense network of 102 sensors was installed to monitor wind direction and velocity, air temperature, relative humidity, radiation, grey globe temperature and rainfall at 1.3 m above the ground, which is a standardised measurement height for determining the variables used to quantify thermal comfort indices. This dataset supports (i) understanding thermal, radiative and aerodynamic processes in urban canyons, (ii) detecting irrigation impact on microclimate, (iii) validating CFD‐based microclimate models and (iv) identifying methods to manage urban heatwaves through water resource optimisation. By encompassing a full year of seasonal and climatic variability, this study is the first to evaluate the combined effects of vegetation type and irrigation on urban thermal comfort in a Mediterranean context, providing a significant contribution to urban microclimate research
The Evolution of the Cocos-North America-Caribbean Triple Junction From Detrital Zircon Analysis
No full textInternational audienceThe tectonic framework and Cenozoic evolution of the Cocos–North America–Caribbean (Co–NA–Ca) triple junction remain subjects of major geological importance due to their complexity and regional impact. New U–Pb zircon geochronology of detrital sediments and detailed structural and geomorphic mapping from southern Chiapas, Mexico, provide insights into the magmatic and tectonic evolution of this plate boundary section. We identify the Escuintla Shear Zone as a lithospheric boundary separating the Chortís Block from North America, connecting eastward to the Motagua Fault and westward to the Tonalá Shear Zone. This structure has functioned as a pathway for Miocene arc magmatism and currently separates pre-Jurassic crystalline rocks to the north from the Huixtla Intrusive Suite to the south—a set of plutons recording protracted magmatic activity from the Cretaceous. Structural and geochronological data show that the Escuintla and Tonalá shear zones accommodated left-lateral motion during the Miocene and were later reactivated as brittle faults, probably during the late Neogene. By integrating new zircon data with previously reported magmatic ages, we refine the timing and rate of the eastward Chortís Block migration (∼21.5 km/m.y.), estimating a total displacement of ∼1,050 km since the Cretaceous. Our results provide new constraints on the crustal architecture and tectonic history of the region and highlight the role of long-lived strike-slip faulting in controlling the spatial organization of arc magmatism and deformation. This region represents a structural node in the diffuse boundary between the Cocos, North American, and Caribbean plates— possibly acting as a true triple junction during recent geological times
Adaptive practices of researchers involved in low-tech co-innovation processes: Feedbacks from a multi-site experience with ICTs for irrigation systems
No full textInternational audienceInformation and CommunicationTechnologies (ICTs) remain poorly used in irrigation systems, particularly at the farm scale and in smallholder farms. ICTs innovations still need to be adapted to each local context to be more accessible to farmers. Coinnovation through a "low-tech" approach can increase the fit of technologies to end users' needs and help farmers to make, maintain and reproduce technological objects. Nevertheless, for researchers, being involved in such co-innovation approaches can be challenging as they have to continually adapt technological interventions to the social and environmental conditions. With the aim of supporting researchers' adaptive practices, this paper proposes an original approach to bring a reflexive stance about how co-innovation unfolds within and across case studies. A methodology to assess the interplay between local contexts, technologies, and facilitation processes from a researcher' perspective was implemented on a multi-country action-research project. Several on-farm experimentations, under a given overarching "low-tech" approach, were documented through qualitative interviews with the researchers involved in their implementation. As in any co-innovation processes, the development of ICTs makerspaces in agricultural settings proposes an alternative way to put ICTs back in the service of farmers. While the process of adapting technology to micro-desires and microenvironments can help restore economic and social accessibility, it also involves a great deal of information and facilitation work. Hence, lowtech approaches are promising solutions to address irrigation efficiency challenges, but their implementation in real world contexts forces researchers to adjust, relocate efforts, develop new facilitating skills, which in turn produces shifts in their position. This research finally raises questions about how to drive change in complex contexts while respecting strictly limited timelines, and opens up perspectives for clustering initiatives and capitalize on researchers' feedbacks.</p
Geometric Characteristics of Dripper Labyrinths and Accumulation of Solid Particles: Simulation and Experimentation
No full textInternational audienceEmitter clogging in drip irrigation systems is a recurring issue, affecting water application uniformity and system lifespan. This study investigated the anti-clogging performance of emitters and the accumulation patterns of solid particles in dripper labyrinths with varied geometric configurations, combining laboratory experimentation and computational fluid dynamics simulations. Fifteen labyrinth models were tested, divided into two groups: (Model A) emitters with well-defined vortexes and (Model B) emitters with uniform flow. The tests were conducted with solid particle concentrations of 125 and 500 mg L−1 over 200 h of operation. The results showed that none of the emitters became clogged, even under severe particle concentration conditions. However, distinct deposition patterns were observed. Emitters with vortex formation accumulated particles in low-velocity zones, especially in the first baffles of the labyrinth. In contrast, emitters with uniform flow minimized sediment buildup, maintaining high velocities throughout the channel section. Simulations confirmed that the relationship between labyrinth geometry and flow velocity directly influences particle deposition. Dripper design strategies aimed at reducing low-velocity zones in the channel could help mitigate clogging risks. The findings of this study provide valuable guidelines for developing more clogging-resistant emitters, contributing to the improvement of drip irrigation systems
Basin closure and water circularity: a pathway analysis from Oum Er Rbia river basin, Morocco
No full textInternational audienceThis water accounting study investigates the dynamics of basin closure in Morocco's Oum Er Rbia basin. It highlights how water and agricultural policies, including dam construction, conservation programmes, agricultural intensification and ever expanding supplies to cities and industry, led to wate scarcity. Reversing this trend requires curtailing demand and balancing economic development with ecosystem health. This explains why integrating water circularity principles (reduce, reuse/recycle, regenerate) at basin level is arduous. Local water circularity initiatives may even decrease return flows and increase water use. Water accounting is, therefore, essential to understand complex trade-offs for basins heading for closure
Role of exposure in adoption and intensity of tree planting practices among smallholder households in Rwanda
No full textInternational audienceAgroforestry, widely promoted across Sub-Saharan Africa to restore degraded landscapes and improve livelihoods, has the potential to positively impact Sustainable Development Goals (SDG), specifically SDG15 (life on land) and contribute towards the achievement of SDG2 (food security) and other SDGs. However, despite substantial investment in agroforestry programs, evidence of program effectiveness in enhancing adoption is inadequate. This paper employed the augmented inverse probability weighting method to analyze the impact of exposure to agroforestry practices on the adoption and intensity of tree planting using panel household data from Eastern Rwanda. The findings show that exposure increased the probability of adoption by 7% ( p = 0.03). A higher probability of adoption (15%, p = 0.01) was observed in households that were exposed both before and after the baseline period, suggesting cumulative effects of exposure over time. Exposure modestly enhanced the diversity of trees and the number of trees in cropping fields, but farmers tended to adopt more exotic than indigenous species. A higher probability of adoption and higher tree numbers were observed when male household members were exposed, and seedling provision enhanced tree numbers and species among adopters. Our findings underscore the need for continuous engagement of farmers and targeted gender-sensitive interventions. We also recommend a more structured approach to training and information dissemination, and a focus seedling availability and a suitable policy environment
Simulation of extreme functionals in meteoceanic data: Application to surge evolution over tidal cycles
No full textWe investigate the influence of time-varying meteoceanic conditions on coastal flooding under the prism of rare events. Focusing on conditions observed over half tidal cycles, we observe that such data fall within the framework of functional extreme value theory, but violate standard assumptions due to temporal dependence and short-tailed behavior.a To address this, we propose a two-stage methodology. First, we introduce an autoregressive model to eliminate temporal dependence between cycles. Second, considering the model residuals, we adapt existing techniques based on Pareto processes. This allows us to build a simulator of extreme scenarios, by applying inverse transformations. These simulations depend on an initial time series, which can be randomly selected to tune the desired level of extremes. We validate the simulator performance by comparing simulated times series with observations, through several criteria, based on principal component analysis, extreme value analysis, and classification algorithms. The approach is applied to the surge data, on the Gâvres site, located in southern Brittany, France.</div
Barriers and drivers for the organic farming of date palm in Moroccan oases
No full textInternational audienceThe potential for date palm organic farming in the oases of Morocco offers a sustainable solution to conventional farming systems and meets growing consumer demand for organic dates. However, transitioning to organic farming presents diverse barriers needing drivers for its emergence. This paper explores the organic date value chain in 10 territorial communities of the Dr & acirc;a-Tafilalet region, identifying barriers and fostering drivers. Field collective and individual surveys were conducted with certified organic, in-conversion, and conventional date palm farmers. Results showed that Mejhoul is the main date palm cultivar used in monocropped farms and promoted for its high-economical value. For date palm fertilization, farmers apply either compost or both compost and livestock manure. Production is marketed both nationally and internationally. Collectors play a central role in the supply chain, aggregating and purchasing dates from production areas to sell to wholesalers, semi-wholesalers, and retailers or to conditioning and packaging stations for export. A significant challenge is the lack of land ownership titles, limiting economic opportunities and investment potential. Our findings suggest that organic dates offer significant potential for farmers, addressing food security and promoting sustainable rural development in oases