A methodology for building agent-base simulations of common-pool resources management : from a conceptual model designed with UML to its implementation in CORMAS

Since 1995, our team has been developing a simulation platform called CORMAS (common-pool resources and multi-agent systems). It provides facilities to build and analyze agent-based models (ABMs) that represent ecosystems where various human activities compete for the use of natural resources. Few agent-based simulations can be mathematically proven, but they can be analyzed inductively. It is therefore important that simulations be replicated before they are accepted as correct. To tackle this thorny issue of ABM replication, we believe that, during the design process, a careful representation of the conceptual model is paramount. In this paper, we advocate using UML (unified modeling language), which is a formal language to describe systems using the object oriented paradigm. An archetypical agroforestry system is presented here, and serves as an example to design a very simple model dealing with common-pool resources management. Different types of UML diagrams are also introduced to describe the static structure of the model, as well as that of the dynamic processes. Adaptation of these diagrams for implementation using the CORMAS platform is detailed. Then, a simple simulation scenario is presented to illustrate how it is done in CORMAS, and a sensitivity analysis on one parameter of the model is conducted. (Résumé d'auteur

ContaMiCuenca : Simulation interactive de l'impact des usages des sols sur la pollution de l'eau dans le Guanancaste (Costa Rica)

Dans le cadre du projet FuturAgua (Belmont - ANR), un processus participatif avec les acteurs de l'eau est en cours. Il a pour but de réduire les conflits autour de l'usage et de la pollution de l'eau dans le Guanacaste, une région sèche au nord-ouest du Costa Rica impactée par des sécheresses récurrentes liées à El Niño et amplifiées par le Changement Climatique. Lors de nombreux ateliers avec des acteurs (municipalité, producteurs, entreprises agricoles, syndicat de l'eau, ministère de l'environnement), nous avons collectivement identifié les principaux problèmes d'eau, priorisé leur importance et défini les objectifs du processus. Les acteurs ont ensuite souhaité développer un outil de sensibilisation et d'éducation environnementale. Nous avons alors élaboré un modèle conceptuel lors d'ateliers participatifs. Puis plusieurs versions du simulateur ont été développées. Cet outil, appelé ContaMiCuenca (en espagnol, " conta mi cuenca " signifie Racontes-moi mon bassin versant, mais fait aussi penser à Contamination du bassin) est un simulateur multi-agents interactif où les principales décisions des agents informatiques sont décidées par les joueurs. Il s'agit donc d'un jeu de plateau assisté par ordinateur qui calcule les mouvements de l'eau superficielle et souterraine ainsi que sa contamination en fonction des différents usages des sols et des précipitations. Ce simulateur a été testé avec des adultes et des enfants et bien sûr avec les participants du projet. Lors de ces séances, ils ont souhaité améliorer la précision du modèle et son réalisme. Ces séances ont aussi permis d'identifier les manques de connaissances sur la pollution des eaux souterraines et la dynamique des aquifères, connaissances qui doivent être approfondies afin d'améliorer notre apprentissage collectif. Des divergences entre les attentes, les objectifs et les agendas des participants ont ralenti le processus participatif. Souvent, ils attendaient des solutions techniques. Surmonter ces contraintes est nécessaire pour une véritable participation à la prise de décisions communautaires pour une gestion intégrée de l'eau

Combining multi-agent simulations and cost-benefit analysis to evaluate policy options for the management of livestock effluents in Réunion Island

This study uses a multi-agent system to simulate the behaviour of economic players in a context of rapidly evolving environmental policy. The area under study is represented by a sector of a French overseas Department, Réunion Island, with a high concentration of pig farms in the upland region and extensive sugarcane plantations in the coastal zone. We first simulate local pig farmers' reactions to several policy options aimed at reducing the pollution coming from pig rearing. Multi-agent simulations are then coupled with cost-benefit analysis in order to calculate the net present value of different policy options. Advantages and limits of the use of the proposed methods to support decision-making are finally discussed. (Résumé d'auteur

Tradition and change in the Southern cone of America. Limits and potentialities of multi-agent systems as methodological tools for the study of the social impacts of territorial dynamics

The territorial transformations that have taken place during the last decade in the South American temperate grasslands - the "Pampas" - have been accompanied by dramatic social changes. As large-scale agribusiness replaces extensive livestock production, agricultural investment fund managers -IFM- break as the newest actors of the reshaped landscape. Unable to reproduce their traditional livelihoods under the growing economic and environmental pressures, many family farmers are selling or renting their properties to IFM while migrating to the cities. Uruguay is a privileged laboratory for the study of this coupled socio-territorial dynamics. As in Argentina and Brazil, Uruguayan Pampas' are being agriculturized2 by large-scale soybean mono cropping. This process is being accelerated by the emergence of the new markets of China and India, the two main soybean importers of the Pampean countries. Bounded by tradition and by values that go beyond profit making, some family livestock farmers strive to avoid rural exodus and to adapt to these new scenarios while maintaining their livelihoods, strongly identified with extensive cattle grazing. Small to medium-sized farmers usually choose between two adaptation strategies: i) to continue with cattle grazing through, a) technological innovation and intensification and/or b) cost reduction; or ii) to abandon livestock production and convert to soybean production. Any of these strategies are threatened, however, by the strong increase of land prices, generated not only by soybean mono cropping (dubbed the "white gold" of South America), but also by major forestry and pulp mill developments. This paper will not focus on the environmental impact of soybean mono cropping in the Pampa biome, an issue which is still highly disputed. It will, instead, offer an interdisciplinar, systemic approach to the social consequences of the land competition between modern, large-scale agriculture and traditional, low input livestock production. How do land concentration and large-scale mono cropping affect the social sustainability of extensive livestock farming systems operating in usually small production units? Is it possible to model - and simulate - simultaneously the dynamics of physical-biological systems interacting with social systems? This article aims at evaluating the interest, contributions and limits of multiple-agent-based simulations or Multi-Agent Systems (MAS) as a methodology to answer to these questions. The underlying hypothesis is that MAS contribute to improve the understanding of the decision-making processes of family farmers, who must decide between sticking to traditional cattle-breeding or investing in the higher and shorter-term profitability of soybean production. However, MAS models must be enhanced through the inclusion of socio (and even psychological) variables allowing to better understand the complex dynamics of land - use related decision making processes. The article's structure has five sections: i) brief introduction of MAS, ii) application of MAS simulations (DinamicaParcelaria) to the specific case of territorial transformations resulting from the dialectic monocropping / livestock family farming in the Uruguayan Pampas, iii) application of MAS simulations (Arapey) to a case study in Northern Uruguay, where the traditional extensive livestock production system has not changed in the last two centuries, remaining as the sole production system iv) crosschecking of the above-mentioned preliminary results with the outcomes of participatory meetings with livestock producers in Uruguay. (Résumé d'auteur

Participatory multi-agent system modelling for collective watershed management in northern Thailand : a companion modeling method

The companion modeling approach was used to facilitate collective learning process of key stakeholders of a highland watershed in northern Thailand, where a socialagroecosystem is located within the multiple political layers of resource uses and management. After analysis the system, role-playing games (RPG) were conducted with stakeholders using simplified rules and virtual environment. Performing the role allowed players understand consequences of individual role on dynamic processes of the whole system. Information obtained from the games supplemented with interviews mutually improved knowledge of both researcher and stakeholders. The design and results from he games were applied to multi-agents system (MAS) model design using Unified Modeling Language (UML). Cormas platform was used to develop computer MAS model to replicate dynamic and phenomena in the games. The aim is to apply in the field allowing stakeholders to verify, experiment interest scenario that could result in alternative sustainable resource management strategies desirable for all parties. (Résumé d'auteur

Facilitating the design of ABM and the code generation to promote participatory modelling

Designing and implementing an ABM is a hard task that needs programming skills besides design skills. This is especially true when dealing with Participatory Modelling (PM) where the model should no longer appear as a black box. On the contrary, participants of a PM process should easily understand the relationship between the outputs of a simulation and the underlying conceptual model, and even contribute to modify it. For that purpose, we have developed an UML Class Diagram Editor that allows the participants to design the structure of their model. Then it generates the source code of the model that can be loaded on Cormas, an ABM platform dedicated to natural resources management. Conversely, the editor is also able to read existing code to generate a diagram by reverse engineering. As autonomous software, our editor can produce standard XMI files and other types of codes. Currently, Cormas is the targeted platform, but code generation can be easily available for other platforms. Obviously the generated code does not enable to run a simulation. It contains only the structure of the model: classes, attributes (with their default value) and associations. Methods to instantiate a simulation and activate the agents still need to be implemented. Nevertheless, Cormas offers many useful methods of its generic classes that can be reused by the specific agents of the modellers. As Cormas is oriented toward interactive simulation, this code generator will greatly facilitate the involvement of stakeholders in participating in the design of models to explore scenarios regarding their own socio-environmental systems

Couplage d'un modèle multi-agent de la dynamique d'une ressource marine avec un modèle multi-agents de l'exploitation halieutique artisanale sénégalaise

La recherche menée dans le cadre du projet MOPA (Modélisation de la Pêche Artisanale) s'insère dans le cadre de la réflexion sur la viabilité des systèmes écologiques et économiques. La modélisation présentée dans ce travail se réfère à la compréhension des conditions de développement durable d'une exploitation halieutique. Compris comme une interaction entre Nature et société, nous nous sommes intéressés aux modalités du couplage au moyen de modèles multi-agents. Le modèle est fondé sur la représentation du comportement des communautés actives (pêcheurs et mareyeurs) en interaction avec la variabilité de la ressource naturelle et du contexte socio-économique dans lequel ils s'insèrent. L'environnement est naturel d'un côté, économique de l'autre. Dans ce cadre, les changements exogènes se réfèrent à l'aspect biologique de l'exploitation (effets des conditions écologiques sur la ressource (e.g., global change, fluctuations de l'upwelling) ou à l'économie de l'exploitation (changement du cours des espèces, valeur de la monnaie). On cherche donc à représenter une exploitation en tant que système dans un environnement, système soumis et répondant à des changements soit exogènes soit endogènes. (Résumé d'auteur