Modélisation robuste de l'impact agrégé de retenues collinaires sur l'hydrologie de surface

En raison du développement de l'industrie légumière, les retenues collinaires à vocation d'irrigation se multiplient dans le département du Morbihan (Bretagne, France). Même si de tels aménagements hydrauliques ont une influence individuelle faible, leur multiplication et leur concentration géographique peuvent avoir des conséquences dommageables sur l'hydrologie de surface. Nous proposons d'utiliser une fonction de transfert de type Hydrogramme Unitaire Géomorphologique, basée sur l'identification de la fonction aire normalisée du bassin versant contribuant effectivement à l'écoulement et sur l'estimation d'une vitesse moyenne d'écoulement dans les thalwegs. Le déterminisme de cette fonction de transfert permet de semi-distribuer l'afflux pluviométrique. Il nous permet en outre de proposer une méthodologie de simulation explicite de l'effet agrégé des retenues collinaires, connaissant leur mode de fonctionnement hydraulique local. Puis, pour le bassin versant pilote de l'Yvel (302 km2), nous étudions a priori l'impact de l'implantation de retenues collinaires selon un scénario géographique de développement préférentiel et pour différents degrés d'intensification.In response to the increasing demand from the food industry for fresh produce, many farms located in the administrative county of Morbihan (Brittany, France) have intensified their vegetable crop production (e.g. peas, beans, spinach) due to their high value. To obtain the best yields and to respect contracts signed with industrial partners, irrigation has been widely used by the farming community to support this production. Since 1989, 500 to 600 ha/year of irrigated farmland have been developed with financial support from state, regional and county agencies. The official purpose of this financing program is to irrigate 50% of the fields cultivated for vegetable crops. Water use for irrigation was estimated to be 6 million m3 in 1999. The demand for irrigation coincides with the period of low water levels in the stream. Thus, there is strong competition with drinking water demands and ecological flow requirements. Moreover, the potential use of groundwater to fulfill these demands is not possible. One of the solutions is to build small headwater dams to store winter flows and use this resource during the growing season. In order to help local public authorities assess their strategy, we need to develop a robust quantification method to study the impact of this development.The 302 km2 Yvel watershed is the site of a highly developed region of small headwater dams because the geological substratum is composed mainly of schist with low groundwater reserves, precipitation is less than the regional average, and the industrial demand for vegetable crops is high. For all these reasons, this watershed is particularly vulnerable. Moreover, from a regional policy point of view, the downstream part of the watershed is located within the Morbihan county whereas the upstream part is located within the Côtes d'Armor and Ille et Vilaine counties, which do not provide any financial support for irrigation development. The current concentration of headwater irrigation dams reflects these regional development incentives as dams are mostly built in the downstream part of the watershed.To study the impact of small headwater dams on watershed hydrology, we propose a conceptual tool built around a geomorphological instantaneous unit hydrograph (GIUH) modelling approach. The GIUH structure, which is based on the effective watershed normalized area function and an estimated mean flow velocity, allows for the explicit accounting of dams and, and thus, can be used for a priori assessment studies. It can also be used in a semi-distributed perspective, where spatial discretization is determined from rainfall variabilities instead of gauging station constraints. These two points allowed us to study three regional irrigation development scenarios: construction of 100, 200 and 300 future headwater irrigation dams. Using two observed rainfall events, we showed that the simulated hydrograph shape at the watershed outlet can be significantly modified. In conclusion, in situ observations and simulation results suggest that : (1) headwater dams do not have any impact when reservoirs are full - lamination is locally observed and thus, does not have any impact on the watershed hydrograph; (2) a spatially homogeneous implementation of headwater dams modifies the watershed hydrograph according to a contributing watershed area ratio; similar behaviour is observed for low water level periods; and (3) localized implementation can be studied through modelling with enough precision to give relevant information to decision makers

Challenges in operationalizing the water–energy–food nexus

Concerns about the water–energy–food (WEF) nexus have motivated many discussions regarding new approaches for managing water, energy and food resources. Despite the progress in recent years, there remain many challenges in scientific research on the WEF nexus, while implementation as a management tool is just beginning. The scientific challenges are primarily related to data, information and knowledge gaps in our understanding of the WEF inter-linkages. Our ability to untangle the WEF nexus is also limited by the lack of systematic tools that could address all the trade-offs involved in the nexus. Future research needs to strengthen the pool of information. It is also important to develop integrated software platforms and tools for systematic analysis of the WEF nexus. The experience made in integrated water resources management in the hydrological community, especially in the framework of Panta Rhei, is particularly well suited to take a lead in these advances

Epistemological dimensions of the water–energy–food nexus approach: reply to discussions of “Challenges in operationalizing the water–energy–food nexus”

We thank the authors, Varis and Keskinen, and Nauditt, for their constructive contributions. We endorse their key comments, further referring to recent literature and events, including the UN 2018 High Level Political Forum on sustainable development. Here, we elaborate on the epistemological perspective of the water–energy–food nexus conceptualization, assessment, discourse and operationalization

Invigorating hydrological research through journal publications

Over the past five years, the editors of a number of journals in the discipline of hydrology have met informally to discuss challenges and concerns in relation to the rapidly changing publishing landscape. Two of the previous meetings, in Götenborg in July 2013 and in Prague in June 2015, were followed by joint editorials (Blöschl et al. 2014; Koutsoyiannis et al. 2016) published in all participating journals. A meeting was convened in Vienna in April 2017 [during the General Assembly of the European Geosciences Union (EGU)] that was attended by 21 editors representing 14 journals. Even though the journals are published in very different settings, the editors found common cause in a vision of the editor’s role beyond just that of gatekeeper ensuring high-quality publications, to also being critical facilitators of scientific advances. In that enabling spirit, we as editors acknowledge the need to anticipate and adapt to the changing publishing landscape. This editorial communicates our views on the implications for authors, readers, reviewers, institutional assessors, and the community of editors, as discussed during the meeting and subsequently

Food and agriculture

Food security has long been a challenge for human societies and will become an increasingly pressing global issue over the coming decades (Fischer, 2018). Although global food production has kept pace with population growth, close to 750 million people (or 10% of the global population) were exposed to severe levels of food insecurity in 2019 (FAO/IFAD/ UNICEF/WFP/WHO, 2020). Unfortunately, this number has increased even further over the course of 2020 due to the COVID-19 pandemic and its economic impacts worldwide. In the 2030 Agenda for Sustainable Development, Sustainable Development Goal (SDG) 2 aims to “end hunger, achieve food security and improved nutrition and promote sustainable agriculture” (UNGA, 2015). The food system is almost entirely supported by water, and agriculture uses the major share of global freshwater resources. However, water use for food production is being questioned continually as intersectoral competition for water intensifies and water scarcity increases. Additionally, in many regions of the world, water for food production is used inefficiently (D’Odorico et al., 2020). This is a major driver of environmental degradation, including depletion of aquifers, reduction of river flows, degradation of wildlife habitats, and pollution (Willett et al., 2019). A fundamental transformation of how water is being managed in the food system is therefore necessary if most of the SDG 2 targets are to be achieved by 2030, without further degradation of water resources to concurrently achieve SDG 6 to “ensure availability and sustainable management of water and sanitation for all” (IFPRI, 2019)

Chronic Delivery of Antibody Fragments Using Immunoisolated Cell Implants as a Passive Vaccination Tool

BACKGROUND: Monoclonal antibodies and antibody fragments are powerful biotherapeutics for various debilitating diseases. However, high production costs, functional limitations such as inadequate pharmacokinetics and tissue accessibility are the current principal disadvantages for broadening their use in clinic. METHODOLOGY AND PRINCIPAL FINDINGS: We report a novel method for the long-term delivery of antibody fragments. We designed an allogenous immunoisolated implant consisting of polymer encapsulated myoblasts engineered to chronically release scFv antibodies targeted against the N-terminus of the Aβ peptide. Following a 6-month intracerebral therapy we observed a significant reduction of the production and aggregation of the Aβ peptide in the APP23 transgenic mouse model of Alzheimer's disease. In addition, functional assessment showed prevention of behavioral deficits related to anxiety and memory traits. CONCLUSIONS AND SIGNIFICANCE: The chronic local release of antibodies using immunoisolated polymer cell implants represents an alternative passive vaccination strategy in Alzheimer's disease. This novel technique could potentially benefit other diseases presently treated by local and systemic antibody administration

Neurodegeneration of the retina in mouse models of Alzheimer’s disease: what can we learn from the retina?

Alzheimer’s disease (AD) is an age-related progressive neurodegenerative disease commonly found among elderly. In addition to cognitive and behavioral deficits, vision abnormalities are prevalent in AD patients. Recent studies investigating retinal changes in AD double-transgenic mice have shown altered processing of amyloid precursor protein and accumulation of β-amyloid peptides in neurons of retinal ganglion cell layer (RGCL) and inner nuclear layer (INL). Apoptotic cells were also detected in the RGCL. Thus, the pathophysiological changes of retinas in AD patients are possibly resembled by AD transgenic models. The retina is a simple model of the brain in the sense that some pathological changes and therapeutic strategies from the retina may be observed or applicable to the brain. Furthermore, it is also possible to advance our understanding of pathological mechanisms in other retinal degenerative diseases. Therefore, studying AD-related retinal degeneration is a promising way for the investigation on (1) AD pathologies and therapies that would eventually benefit the brain and (2) cellular mechanisms in other retinal degenerations such as glaucoma and age-related macular degeneration. This review will highlight the efforts on retinal degenerative research using AD transgenic mouse models

Twenty-three unsolved problems in hydrology (UPH) – a community perspective

This paper is the outcome of a community initiative to identify major unsolved scientific problems in hydrology motivated by a need for stronger harmonisation of research efforts. The procedure involved a public consultation through on-line media, followed by two workshops through which a large number of potential science questions were collated, prioritised, and synthesised. In spite of the diversity of the participants (230 scientists in total), the process revealed much about community priorities and the state of our science: a preference for continuity in research questions rather than radical departures or redirections from past and current work. Questions remain focussed on process-based understanding of hydrological variability and causality at all space and time scales. Increased attention to environmental change drives a new emphasis on understanding how change propagates across interfaces within the hydrological system and across disciplinary boundaries. In particular, the expansion of the human footprint raises a new set of questions related to human interactions with nature and water cycle feedbacks in the context of complex water management problems. We hope that this reflection and synthesis of the 23 unsolved problems in hydrology will help guide research efforts for some years to come