A conceptual model for multipoints of view analysis of complex systems. Application to the analysis of the carbon dynamics of village territories of the west African savanna

Belem Mahamadou. 2009. A conceptual model for multipoints of view analysis of complex systems. Application to the analysis of the carbon dynamics of village territories of the west African savanna. Montpellier : AgroParisTech, 189 p. Thèse de doctorat : Informatique et simulation : AgroParisTech

Titre français : Un modèle conceptuel pour la représentation et l'analyse multi-points de vues des systèmes complexes. Application à l'analyse de la dynamique des ressources en carbone des terroirs villageois de la savane ouest-africaine

Encadrement : Müller, Jean-Pierre

Résumé : Modelling complex systems that cover multiple domains, for their better understanding, increasingly demands collaboration between different disciplines. However, these disciplines do not necessarily share the same points of view on the real objects of the system, and these can be complementary. In addition, the representation of such systems requires multi-scale description implying at least the local (individual), global and underlying environment. This PhD work proposes (1) a conceptual framework for complex systems analysis and representation from different points of view at the global and the local levels while taking into account the environment and (2) its application to the representation and analysis of the carbon dynamics from plot to village levels in the West African savannas (WAS). Using multi-agent system (MAS) organizations-centered approach, the Organization-Role- Entity-Aspect (OREA) meta-model has been proposed to represent a complex system from different points of view. At the global level a point of view is reified as an organization made of the roles the entities can play in the organization; at the local level the points of view decompose an entity internal structure in a set of aspects. Through the concept of role, an entity can play different roles in different organizations. Through the concept of aspects, an entity can play a role in different ways. OREA is an extension of the Agent-Group-Role meta-model where: (1) roles are not limited to agents but can be assigned to any kind of object (including the environment), (2) the decomposition does not only apply to the organizations only, but also to the entities themselves, (3) the use of the framework for knowledge representation rather than a pure software engineering paradigm is emphasized. OREA provides a framework to specify explicitly and separately the macro and the micro levels. The macro-level in OREA is specified without any assumption on the micro-level. The macro-level is relevant to the "what" while the micro-level is concerned by the "how". The environmental objects are explicitly defined in the organization structure allowing defining the perception of the environment by the entities through their roles. The OREA methodology allows specification of the structure of a system based on the identification of the scales of description and their underlying processes. The OREA model has then been used for the modelling of the carbon (C) dynamics from plot to village levels in the WAS. Carbon is an important determinant of the sustainability of West African farming systems and of the greenhouse effect. To deal with the complexity of C dynamics various models have been developed to simulate and predict carbon dynamics. These models are mathematical, process-based or individual-based. To better include social and economic dimension and handle system heterogeneity a generic multi-agent model for the analysis of C dynamics at the village level, CaTMAS (Carbon Territory Multi-Agent Simulator), has been designed and implemented. CaTMAS assumes that a better analysis of C dynamics at the village level requires consideration of (1) social, economic, physical and biological factors, (2) the individual's actions and the multiplicity of interleaved dynamics. CaTMAS is based on the OREA model, the MAS approach, and coupling with the Century model and a Geographic Information System. The model allows a multiple-point-of-view analysis of C dynamics as organisations made of roles played by entities through various aspects. CaTMAS not only provides a framework for an explicit and realistic description of a farming system but also allows assessment of the viability of farming systems under various socio-economic and bio-physical scenarios. The model integrates the interactions between the human's activities and the environment and some environmental feedbacks. Using CaTMAS, it is possible to analyze how population growth impacts C dynamics and vice-versa. The model has been used to analyze the impacts of climate and economic change on the one hand, and of two cropping systems on the other hand, on the C dynamics of the village territory. Future efforts on the OREA model should focus on improving the methodology and the verification and on taking into account the holonic representation. Developments on CaTMAS could include enlargement of simulations to the country scale and integration of the economic potential of the C market at the national, regional and the local levels.

Mots-clés Agrovoc : modèle de simulation, cycle du carbone, village, système de culture, changement climatique

Mots-clés géographiques Agrovoc : Afrique occidentale

Mots-clés libres : Systèmes multi-agents, Modélisation conceptuelle, Multi-points de vue, Cycle du carbone

Classification Agris : U10 - Informatique, mathématiques et statistiques
P40 - Météorologie et climatologie
P33 - Chimie et physique du sol

Champ stratégique Cirad : Axe 1 (2014-2018) - Agriculture écologiquement intensive

Auteurs et affiliations

• Belem Mahamadou, CIRAD-ES-UPR GREEN (FRA)

Source : Cirad-Agritrop (https://agritrop.cirad.fr/591805/)

Métriques

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