There is no translation available.

Le bassin de Bouregreg au Maroc, est très peuplée, avec une agriculture intense et un climat semi-aride. L'irrigation s'étend sur la plaine et elle est assurée par les oueds, et par un pompage généralisé de l’eau souterraine qui connait un épuisement. Dans les conditions actuelles de diminution des précipitations, de diminution des apports des oueds et de l'augmentation de la demande en eau d'irrigation, l’eau souterraine est de plus en plus surexploitée et connait une baisse accélérée qui menace la durabilité de la ressource et de l’irrigation. Dans ce contexte, il est nécessaire de caractériser l’eau souterraine utilisée pour l’irrigation et évaluer sa durabilité.

La présente thèse a pour objectifs de délimiter les zones de recharge, d’identifier les sources de recharge (eau de pluie, oueds, retours d’irrigation), d’analyser les contaminant émergents dans les aquifères, et d’analyser la relation hydraulique entre l’amont (zone potentielle de recharge) et l’aval (zone d’exploitation). Les résultats obtenus serviront à évaluer la durabilité de la ressource en eau en identifiant les ressources renouvelables de celles non renouvelables, en étudiant les processus de recharge et d’écoulement, et en mettant en évidence l’évolution de la qualité des eaux souterraines du bassin.

 

Mots clés : recharge des eaux souterraines, qualité des eaux souterraines, ressources en eaux souterraines

 

In a context of increasing pressure on water resources, the search for better agricultural productivity of irrigation water leads to optimize watering schedules according to soil water conditions and crop development stages. Spatial remote sensing can now provide spatialized information in near-real time on soil and vegetation characteristics. In particular, radar data have shown great potential for estimating soil moisture. Similarly, optical data have been used for a long time to estimate vegetation parameters (leaf area index, biomass...). This information can be integrated in crop models to simulate in real time the evolution of the yield. The general objective of the thesis is to show how information from high spatial and temporal resolution remote sensing can be used to retrieve the water and vegetation dynamics of an irrigated area. The approach is based on experiments carried out on an irrigated cereal (maize) plot system, with spatial and ground observations with high temporal repetitivity, and the use of a crop model.

 

The first part of the thesis aims to evaluate the characterization of soil parameters (roughness and moisture) and vegetation by coupling radar remote sensing data in C and L bands (respectively Sentinel-1 and ALOS-2/PALSAR) and optical (mainly Sentinel-2). The coupled use of C- and L-band data will allow a better estimation of soil moisture due to a better penetration of the L-band radar wave in dense agricultural canopies. In addition, we should be able to jointly estimate soil moisture and soil roughness. The current availability of L-band data (ALOS2/PALSAR) and the planned launch of new L-band sensors (SAOCOM-1A and NISAR) gives this objective a strong scientific legitimacy. Vegetation parameters such as LAI will be computed from Sentinel-2 optical data.

 

The second component, conducted in parallel, will consist in the realization of a remote sensing module for the Optirrig crop model, developed at the UMR G-Eau (Montpellier) and involved in many academic and operational partnerships. The challenge of this component will be at least to carry out the forcing of observations obtained by remote sensing and if possible to go towards data assimilation in the mathematical sense (i.e. allowing a recalibration of the model parameters).

 

Key words :  remote sensing, Optirrig, irrigation, Sentinel-2, vegetation, LAI, soil moisture

 

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Figure 1: Illustration of the difference (E) between the LAI without irrigation (LAI0i) and the noisy one (vLAI) representing the LAI derived from remote sensing that allows us to identify evidence of irrigation between the Sentinel-2 images (ti)

The lens of agroecology has, to date, seldomly been used to study farming systems and cropping systems in North Africa, even the more in irrigated zones. Yet, agroecological practices are common within small-scale irrigated farming systems, although often undertaken in combination with more conventional practices.

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© Photos : preparation of manure tea (Leauthaud et al. submitted)

 

 

In particular, one innovation that has spread with the use of drip-irrigation and fertigation strategies, is the use of manure-based teas, applied to various fruit and green market products. This bottom-up innovation remains mostly invisible to decision makers and researchers, while questions arise concerning its composition, agronomic effects as well as its interactions with the soil, and in the case of fertigation applications, its role on pipe and drip emitter clogging. This project aims to conduct original research bridging irrigation science - agronomy- soil science and participatory processes, within the framework of a collaboration between the two research units Eco&Sols and Geau.

The team will initiate a PhD-level research work, aimed at improving fertigation practices of farmers, by characterizing and co-experimenting with farmers improvement pathways of this locally existing innovative agroecological practice of artisanal manure-based tea extracts in irrigated agriculture in North Africa.

 

Three specific questions, in particular, underlie this goal:
  • What are the major physico-chemical and biological properties of artisanal manure teas?
  • What are the impacts on soil physicochemical and biological properties, on crop growth and on the irrigation system?
  • How, and in which conditions, can the implementation of participatory processes in co-learning lead to improved fertigation strategies of farmers, and in fine to more virtuous uses of organic liquid fertilizers?
 
To bring answers to these questions, the PhD candidate will:
  • Undertake with farmers a participatory co-design process to initiate collaborative reflections on improvement of fertigation strategies, by (i) describing the use of manure tea by farmers, and (ii) implementing a set of workshops with the famers to co-design novel solutions. This will be implemented in two to three different sites in Tunisia. 
  • Uundertake experimental characterizations of (i) used manure teas, and its impact on the (ii) soil, cropping and (iii) irrigation systems.

 

Key words: manure teas, fertigation, irrigated agriculture, co-design processes, physicochemical and biological properties.

image2© Photo : I. A. Ramos-Fuentes (Sun’Agri 3 – 2021)

 

 

Access to drinking water is declining in most countries (Burek et al., 2016), due to several demographic and climatic factors, as well as inefficient management of water resources, especially in agriculture. In France, irrigated agriculture is an important activity, mainly concerning arable crops (corn and other cereals), in a context where water use restrictions are proving to be more and more frequent, especially in the Mediterranean countries. It has been shown that "well thought out" cultivation under agrivoltaic systems can reduce water requirements and maintain a level of production comparable to that of open-air growth.

 

 

image1© I. A. Ramos-Fuentes (Sun’Agri 3 – 2021)

 

 

The dynamic agrivoltaic devices (DAV) would allow additional control over the system via the control of the rotation of the panels, to reduce the heterogeneity of the distribution of rainfall resulting from their presence. These tracking systems also involve more complex optimization questions, in particular, because the movement of the panels changes the spatial and temporal patterns of the cast shadow and therefore the plant's response to these heterogeneities. Therefore, the water balance of the soil, the water requirements of the crop, its growth, and its biomass production must be described by processes specific to the dynamic agrivoltaic context. This is particularly the case for field crops, as they are crops with long cycles, exhibiting more complex physiology and diverse radiation responses (type C3 or C4 metabolisms; Campillo et al., 2012). These are also crops for which constraints on irrigation will certainly exist and will have to be simulated (adaptation of irrigation techniques, availability of the resource) to optimize the use of water.

 

Keywords: Dynamic Agrivoltaics; Irrigation; Crop modeling; Water optimization; Field crops

In a global scenario of population growth, increased urbanisation, strong pressure on water resources and an increase in the frequency of extreme temperatures, urban hot spots will be more pronounced, more difficult to combat and their deleterious effects will affect an increasingly large population. These findings call for initiatives to build resilient cities based on the analysis of new data sources, resources and the use of water of all qualities present in urban areas. The objective of this thesis is to evaluate the capacity of vegetation to improve the quality of life of the population and the urban ecosystem. The methodology chosen for this purpose is the multi-scale modelling of the energy balance existing between the building, the substrate of the vegetation and the vegetation itself, and the interactions with the turbulences of the urban canopy. The idea is to identify the direction, geometry, temporality and relative importance of the heat flows (conduction, convection, radiation and phase change) involved in the system. We will attempt to identify quantitatively what is the attenuation of urban temperatures and how to optimize the performance of vegetation to contribute to build smarter and perennial cities.

image1 ©ADEME, 2021

 

 

 

 

In addition to the production and analysis of micro-climatic and agronomic data, modelling work and similarity experimentation are also planned. The objective of this thesis is to develop a systemic approach and to produce an integrated model allowing to couple crop growth and aeraulics in order to help decision making in terms of the choice of vegetalisation of cities according to various hydraulic, thermal, energetic and aesthetic constraints. This model, which will work at the scale of a meter, can then be coupled with meteorological models adapted to cities or heat exchange models of buildings.

 

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Key words : Urban Vegetation, Numerical Simulation, Computational Fluid Dynamic, Crop Model, Smart Cities.

There is no translation available.

Cécile Hérivaux a soutenu ses travaux de thèse en Validation des Acquis de l’Expérience (VAE) intitulés "Economie de la soutenabilité et protection des eaux souterraines" le 16 décembre 2021 à 14h à Montpellier Supagro,

devant le jury composé de :

  • Harold LEVREL, professeur, AgroParisTech, UMR CIRED                                                           Rapporteur
  • Anne ROZAN, professeure, ENGEES, UMR GESTE                                                                       Rapporteur
  • Carole SINFORT, professeure, l’Institut agro-Montpellier SupAgro                                        Présidente du jury
  • Damien JOURDAIN, professeur associé, CIRAD, CEEPA                                                             Membre invité
  • Marielle MONTGINOUL, directrice de recherche, INRAE, UMR G-EAU                                  Référente scientifique

 

Résumé :

Ce mémoire porte sur les approches économiques en réponse aux problématiques associées à la protection des eaux souterraines. Il a été préparé en vue de l’obtention du doctorat en Sciences Economiques par la Validation des Acquis de l’Expérience (VAE). La première section présente parcours professionnel et scientifique, au travers des différents projets de recherche appliquée sur lesquels je me suis impliquée, les publications qui en ont résulté, ainsi que les activités de formations et les principales collaborations scientifiques. Mes travaux de recherche mobilisent les concepts et outils principalement issus de l’économie de l’environnement et des ressources naturelles, en les adaptant aux spécificités des eaux souterraines et des aquifères (échelle de temps et d’espace), en les combinant avec des approches issues d’autres disciplines (modélisation hydrogéologique, modélisation des changements d’usage des sols, approches socio-culturelles) et avec la participation des acteurs des territoires étudiés tout au long de la démarche (ateliers, entretiens, enquêtes). La seconde section résume ces travaux en les organisant autour de leurs apports aux quatre principes de l’économie de la soutenabilité : (i) une approche systémique intégrant activités humaines et aquifères, (ii) la prise en compte du temps long, (iii) les approches coût-efficacité appliquées aux programmes de restauration de la qualité des eaux souterraines et (iv) la prise en compte des dimensions de justice inter, intra-générationnelle et intrinsèque à la nature dans l’évaluation des bénéfices associés à la protection des eaux souterraines. Pour chacun de ces principes, le mémoire décrit les démarches scientifiques développées et appliquées sur différents territoires, les résultats et les principaux enseignements associés, ainsi que les perspectives de recherche.

photo Dominguez © Photo : Juan Dominguez 2021 - Irrigated corn cultivation under soil conservation agriculture

In the South of Europe, climate change leads to an increased frequency of drought episodes and a rise in temperatures with the consequence of an increase in crop evapotranspiration and the degradation of soil water balance. Irrigation could represent a solution to mitigate the effects of drought and ensure the sustainability of agricultural production.

There is no translation available.

La fabrique d’une anthropologie « chez » les hydrologues repose sur une pratique scientifique originale, qui interroge la rencontre des sciences de la nature et celles de la société, ainsi que le rôle de l’anthropologue dans ce contexte interdisciplinaire.
À partir de son expérience, Jeanne Riaux analyse la manière dont des scientifiques de disciplines différentes travaillent sur un même terrain et construisent un raisonnement commun.
 
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