• Energy Research

Dans de nombreuses villes méditerranéennes comme Alger, l’étalement urbain et les effets néfastes des changements climatiques affaiblissent progressivement de vastes zones agricoles de haute qualité. Pour s’adapter aux effets de ces phénomènes et les atténuer, les pouvoirs publics ont initié des politiques publiques de développement urbain, allant de la stratégie de la ceinture verte à la politique des 23 agriparcs. L’objectif de cet article est d’expérimenter la voie d’une alternative qui exalte la constitution d’un territoire agriurbain durable. Une méthode de double durabilité (interne et externe) proposée par Ba et Aubry (2011) est appliquée et développée dans la commune de Chéraga, afin de fournir un premier diagnostic global sur la durabilité de l’agriculture urbaine présente dans les agriparcs. Ceci nous permet d’identifier plusieurs enjeux majeurs, en vue d’optimiser la durabilité de l’agriculture urbaine, réduire les carences et remédier aux déséquilibres constatés.

For vegetable farmers, climate change brings many issues and its impacts may vary by regions and crops. The objective of our exploratory study was to develop a participatory process to investigate collectively with vegetable farmers their priorities and needs to adapt to climate change based on climate data relevant to them. Our work relied on an iterative process involving workshops with agricultural experts and vegetable farmers on 3 contrasting territories of the Parisian Region and climate projections using DRIAS (Data on French Regionalized climate scenarios and Impacts on the environment and Adaptation of Societies). We first identified the relevant climate factors and thresholds to which specific vegetables are particularly sensitive. Simulations, downscaled at the local level (8*8km area) of the relevant climate factors were provided and discussed with farmers. This allowed us to refine the main climate factors that were judged relevant by farmers to support their strategic thinking about adaptation to climate change. This climate factors were presented at the temporal scales judged relevant by farmers: (i) comparison of reference years of the past 1990-2020, near future 2020-2040, far future 2040-2060, (ii) seasonal scale (winter, spring, summer, autumn). This information, explained to farmers on short videos, was used to carry out an online survey in order to identify the future actions to prioritize to adapt vegetable production to climate change from farmers’ perspective in terms of practice exchanges between farmers, training, experimentation, public policy (work in progress). As interactions with farmers showed a strong concern about water use, a dedicated collective workshop will be organized in autumn 2022, combining (i) projections of water availability in the region, (ii) modelling of increased water needs by farmers, (iii) involvement of local authorities to discuss water regulations and governance. To our knowledge, this study is the first attempt to involve vegetable farmers in a collective participatory process about adaptation to climate change based on climate projections with indicators and temporal scales relevant to their specific needs.

Dans un contexte de déprise des exploitations agricoles spécialisées en cultures légumière ou fruitière, et, paradoxalement, d’une attente sociétale accrue pour des productions de qualité et de proximité, et pour des formes agricoles multifonctionnelles, le modèle de revitalisation agri-urbaine proposé offre un nouveau regard sur les potentialités des friches périurbaines. Le projet porte sur l’évaluation d’une expérimentation de revitalisation par le maraîchage hors-sol, la location de jardins et l’accueil pédagogique, d’une friche périurbaine polluée dans les Yvelines (78). Une évaluation de systèmes de cultures organiques ou hydroponiques hors-sol a permis de définir les usages propres à chacun d’eux. Un réseau de partenaires et un guide méthodologique ont été créés autour de la revitalisation agriurbaine. In a context of abandonment of vegetable or fruit crops specialized farms, and paradoxically, an increasing societal expectation for quality productions and proximity, and for multifunctional agricultural forms, the proposed model of agri-urban revitalization offers a new prospect at the potentialities of periurban wastelands. The project focuses on the evaluation of a revitalization experiment by off-ground above-ground market gardening, the rental of gardens and the educational reception, of a polluted periurban wasteland in the Yvelines (78). By the evaluation of off-ground organic or hydroponic cultivation systems, the specific uses of each of them have been defined. A network of partners and methodological guidelines have been created around agri-urban revitalization.

Urban planners are increasingly interested in agriculture around cities and have to decide whether to maintain or not areas of agricultural land use within and close to growing cities. There is therefore a need for researchers to design tools to guide public decision-making on land use. Various approaches, originating from different disciplines, may be adopted in this respect. We designed an interdisciplinary research program in order to test two related concepts: the "sustainability" and the "multi-functionality" of agriculture. We show that these concepts provide a useful framework for obtaining appropriate knowledge about urban agriculture, which urban planners could apply in real situations. In close collaboration with urban planners, we applied an interdisciplinary research methodology, based on common farm surveys and territorial approaches, to the Antananarivo area (Madagascar). The main functions analyzed were the food production and environmental roles of urban agriculture. Two aspects of sustainability were assessed: the farm sustainability and the territorial sustainability, with expert scores. This approach identified a wide diversity of farming systems that performed differently, depending on their intra- or suburban location. The food supply function appeared to be important not only for fresh produce but also for rice consumption. The function of protection against flooding is now important and this importance will increase with climate change. A diagnosis of sustainability was made and discussed with urban planners: several farming systems and zones were identified in which agriculture was considered important as a means of maintaining or developing the food supply, employment and incomes, and even landscape or environmental quality. We also identified other areas in which poor production conditions and/or the negative effects of urbanization on agriculture jeopardized its sustainability. This methodology appeared to be useful for determining the most appropriate role of urban agriculture in the land-use planning of this city. Our study raises new questions on the subject and should lead to more focused research programmes. We discuss several points of interest and the limitations and possible extension of this method.

Social, economical and environmental conditions of Urban Agriculture are very different between industrialized and developing countries, some research models and operational tools may be similarly questioned by this agriculture. In three case studies: in Senegal, France and Madagascar, where agro-economic surveys where done in punctual or long-term research programs, we question the renewal of the representation of farming systems' diversity, the duality of the concepts of sustainability and the analysis of multi-functionality of Urban Agriculture according to different actors. The global activity system must be taken into account due to the frequency of external activities to understand the agricultural production system itself. An external sustainability, i.e. the vision the urban planners and residents have about Urban Agriculture compared to other urban uses of land, is as important as the classical internal sustainability of farming systems to diagnose the future of urban agriculture. The place the urban planners give to agriculture in urban projects depends on the functions they or the inhabitants recognize to it. Thus, research must analyse them and lighten the hierarchy of functions made by these different stakeholders. The analysis of multifunctionality of urban agriculture crossed with internal and external diagnosis of sustainability is an important tool to help urban decision-makers to consider agriculture in urban planning.

Depending on the city and its socio-geographical context, urban and peri-urban agriculture presents different types of production systems. Considered as a way to alleviate poverty, this type of agriculture has gradually acquired certain legitimacy in urban projects. In a study carried out in Dakar, we investigated six categories of stakeholders - from the agricultural and policy-making sectors - to analyze their perception of this type of agriculture in areas like Niayes (interdune depressions which very favorable to agriculture), and to characterize the production systems. By adopting an innovative analytical approach, we were able to highlight the following: a typology of farms representing the diversity of production systems and household activities, an analysis of their location in four agricultural zones differentiated by urban proximity, the variability of the internal and external sustainability of farms, an analysis of multi-functionality of agriculture and agricultural areas based on the perception of the six categories of actors. These elements provide new insights into various stakeholders. However, in order to provide solutions for the various problems faced by this type of agriculture, we suggest scientific and technical solutions such as the creation of an agriculture observatory.

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