Simulating Rural Environmentally and Socio-Economically Constrained Multi-Activity and Multi-Decision Societies in a Low-Data Context: A Challenge Through Empirical Agent-Based Modeling

Development issues in developing countries belong to complex situations where society and environment are intricate. However, such sites lack the necessary amount of reliable, checkable data and information, while these very constraining factors determine the populations' evolutions, such as villagers living in Sahelian environments. Beyond a game-theory model that leads to a premature selection of the relevant variables, we build an individual-centered, empirical, KIDS-oriented (Keep It Descriptive & Simple), and multidisciplinary agent-based model focusing on the villagers\' differential accesses to economic and production activities according to social rules and norms, mainly driven by social criteria from which gender and rank within the family are the most important, as they were observed and registered during individual interviews. The purpose of the work is to build a valid and robust model that overcome this lack of data by building a individual specific system of behaviour rules conditioning these differential accesses showing the long-term catalytic effects of small changes of social rules. The model-building methodology is thereby crucial: the interviewing process provided the behaviour rules and criteria while the context, i.e. the economic, demographic and agro-ecological environment is described following published or unpublished literature. Thanks to a sensitivity analysis on several selected parameters, the model appears fairly robust and sensitive enough. The confidence building simulation outputs reasonably reproduces the dynamics of local situations and is consistent with three authors having investigated in our site. Thanks to its empirical approach and its balanced conception between sociology and agro-ecology at the relevant scale, i.e. the individual tied to social relations, limitations and obligations and connected with his/her biophysical and economic environment, the model can be considered as an efficient "trend provider" but not an absolute "figure provider" for simulating rural societies of the Nigrien Sahel and testing scenarios on the same context. Such ABMs can be a useful interface to analyze social stakes in development projects.Rule-Based Modelling, Rural Sahel, Confidence Building, Low-Data Context, Social Criteria

Benchmarking humanitarian support : empirical agent-based modeling of development action types in Nigerian villages

International audienceThe purpose of this article is to simulate and analyze the impacts of development interventions on the population of three different sites in Sahelian millet-cropping Niger (Sahelian Africa), taking account the differentiation of social and agro-ecological constraints on the different types of villagers. The work is based on a previous article (Saqalli, 2006), which has shown that using an individual Agent-based model (ABM) is a relevant approach to integrate agro-ecological, social and economic characteristics of a system and that family internal rules have strong impacts on village and environment evolutions. Two development project interventions are simulated in a context of no land scarcity: inorganic fertilizers availability for farmers and an inventory credit technique based on millet yields that some villagers may choose to use. Two rationalities are tested, one upon economic values and the second upon the intra-village "reputation" gains. Our results illustrate that a village cannot be considered as a whole and project operators must take in account the precise target population rather than all adult villagers. Project involvements concern only sites where savings for securization or intensification are possible: These proposals need actually some food security and investment capacities that are largely conditioned by family manpower and size. Inorganic fertilizers have little success without any intensification process in a context of good land availability. Inventory credit intervention engages a maximum of 25% of the population in the site with medium agro-ecological conditions. Reputation has little effect on the population behavior and should be considered more as a local wealth estimation factor between villagers. Therefore, one should consider these proposals as a potential support tool for a limited part of the population capable to go beyond the survival level,but not as a global poverty-alleviation panacea

Targeting rural development interventions : empirical agent-based modeling in Nigerien villages

International audienceThe aim of this article is to analyze the impact of development interventions on the population of three Nigerien villages that differ in terms of their agro-ecological, social and economic characteristics. This is performed by simulating the behavior of individuals in an agent-based modeling framework which integrates the village characteristics as well as the family internal rules that condition access to economic and production activities. Villagers are differentiated according to the social and agro-ecological constraints they are subjected to. Two development project interventions are simulated, assuming no land scarcity: increasing the availability of inorganic fertilizers for farmers and an inventory credit technique based on millet grain. Two distinct approaches were used to model the rationale of farmers' decision making: gains or losses in economic value or gains or losses in within-village ''reputation''. Our results show that village populations do not respond en masse to development interventions. Reputation has little effect on the population behavior and should be considered more as a local proxy for wealth amongst villagers, suggesting the monetization of these societies. Populations involve themselves in the two simulated development interventions only at sites where savings are possible. Some level of household food security and investment capacity is actually required to take part in the development interventions, which are largely conditioned by family manpower and size. As long as uncultivated land remains available in the village territory, support for inorganic fertilizers has little impact in the absence of any intensification process. Inventory credit engages a maximum of 25% of the population at the site with medium agro-ecological conditions. Therefore, both interventions should be viewed as a potential support tool for a limited part of the population capable of going beyond the survival level, but not as a generic poverty-alleviation panacea

Testing Social-driven Forces on the Evolution of Sahelian Rural Systems: A Combined Agent-based Modeling and Anthropological Approach

International audienceThis article presents the results of a methodology combining an extensive fieldwork, a formalization of field-based individual rules and norms into an agent-based model and the implementation of scenarios analyzing the effects of social and agro-ecological constraints on rural farmers through the study of three different sites in Nigerien Sahel. Two family transition processes are here tested, following field observations and literature-based hypotheses: family organizations can evolve between a patriarchal mode and a non-cooperative one because of family income redistribution tensions. Family inheritance systems can shift between a "customary" mode and a "local Muslim" one through family land availability tensions. Our results show that both agro-ecological and socio-economic characteristics determine the simulated family type distribution and consequently the allocation of resources. Results from simulations with no evolution processes show that villages specialize themselves on different economic activities according to natural resources: An intensification gradient is observed from the most favored site, with more local productions and improved ecological indicators, to the less-favored one, with a growing proportion of the population wealth coming from migration remittances and "off-shore" livestock. Once introducing such processes, the differentiation also occurs within the population level, subdividing it into specializing groups according to their size, their assets and their social status. Emerging individualistic family types increase the village populations' robustness through different and site-specific evolutions

Reconstituting family transitions of Sahelian western Niger 1950-2000 : an agent-based modelling approach in a low data context

International audienceThis research analyses the impacts of the family organization on the diversity of income sources and the sustainability and the dynamics of rainfed farming systems of Sahelian Niger, through an individual-centred agent-based model which variables were defined through anthropological investigation. Results show that family organisation has strong effects on wealth levels and distribution and on demographic growth. They also suggest a historic shift from the patriarchal mode to a mono-nuclear mode in the 70's in this specific area, due to a higher resilience of the latter thanks to a broader diversification and a better adequacy between wealth and family demograph

Tillage-induced spatial distribution of surface crusts on a sandy paleustult from Togo

The spatial distribution of crusts in coarse-textured soils and the processes affecting it are poorly documented, despite the potential impact of crusts on water infiltration. This study addresses the influence of tillage-induced microrelief on the morphology and spatial distribution of surface crusts in an oxic paleustult from southern Togo (West Africa). Replicate 1 m2 plots were exposed to 217 mm of natural rainfall during a 6-wk period, during which the surface topography was measured three times. Subsequently, 24 undisturbed crust samples were used for micromorphological analysis. The crusts exhibited a range of morphologies but were nevertheless adequately mapped and characterized according to two main types. Type 1 crusts (= runoff crusts) showed several superposed clay bands, 100 to 500 mm thick, buried within a micromass-depleted sand layer lesser or equal to 12 mm thick. Type 2 crusts (= erosion crusts) had an exposed clay band a few tenths of a millimeter thick. The spatial distribution of crusts at the time of sampling appeared better correlated with the initial than with the final microtopography of the plots. These findings suggest that crust distribution should be regarded as history dependent and that erosion and deposition processes largely governed the development of the crusts. This latter aspect is in agreement with the recent crust genesis model of Valentin and Bresson, as is the fact that clay bands in our plots were laterally continuous at all observational scales lesser or equal to 0.1 m. Other mechanisms proposed in the literature for the developement of clay bands did not seem able to account adequately for the observed pattern. (Résumé d'auteur

Caractérisation morphologique des cuvettes oasiennes du Centre-Est du Niger

peer reviewedSituées en zone semi-aride à aride du Niger, les cuvettes oasiennes du département de Gouré sont actuellement menacées d'ensablement en raison de la dégradation du couvert végétal et d'un accroissement de l'efficacité érosive des vents. Afin de comprendre les processus d'ensablement autour de ces cuvettes, une caractérisation de leurs formes et orientations a été entreprise. Le coefficient de compacité de GRAVELIUS a permis de mettre en évidence des cuvettes circulaires (8,5 %), ovales (46,8 %), amiboïdes (10,9 %), étirées (17,6 %) et très étirées à tendance amiboïde (16,1 %). Les cuvettes oasiennes de forme circulaire ou ovale renvoient à des drains partiellement comblés par les apports éoliens. Les formes étirées et très étirées sont liées à un morcèlement du réseau hydrographique par des édifices dunaires. Enfin, la mesure de l'orientation a permis d'apprécier la distribution entre quatre secteurs majeurs : E-O (22,8 %), N-S (21,4 %), NE-SO (21,6%) et SE-NO (34,3 %). Les cuvettes orientées E-O et NE-SO sont associées à des dunes longitudinales et celles orientées N-S et SE-NO à des dunes transversales

Identifying determinants, pressures and trade-offs of crop residue use in mixed smallholder farms in Sub-Saharan Africa and South Asia

<p>Crop residues (CR) have become a limited resource in mixed crop-livestock farms. As a result of the increasing demand and low availability of alternative resources, CR became an essential resource for household activities, especially for livestock keeping; a major livelihood element of smallholder farmers in the developing world. Farmers' decisions on CR use are determined by farmers' preferences, total crop production, availability of alternative resources and demand for CR. Interaction of these determinants can result in pressures and trade-offs of CR use. Determinants, pressures and trade-offs are shaped by the specific socio-economic and agro-ecological context of these mixed farms. The objective of this paper is to provide a comparative analysis of the determinants of CR use and to examine some options to cope with pressures and trade-offs in 12 study sites across Sub-Saharan Africa and South Asia. Drawing on socio-economic data at household and village level, we describe how cereal intensification and livestock feed demand influence use, pressures and trade-offs of CR use across study sites, specifically cereal residue. Our results show that in low cereal production and livestock feed demand sites, despite a low demand for CR and availability of alternative biomass, pressures and trade-offs of CR use are common particularly in the dry season. In sites with moderate cereal production, and low-moderate and moderate livestock feed demand, alternative biomass resources are scarce and most residues are fed to livestock or used to cover household needs. Subsequently, pressures and potential trade-offs are stronger. In sites with low cereal production and high livestock feed demand, pressures and trade-offs depend on the availability of better feed resources. Finally, sites with high cereal production and high livestock feed demand have been able to fulfil most of the demand for CR, limiting pressures and trade-offs. These patterns show that agricultural intensification, better management of communal resources and off-farm activities are plausible development pathways to overcome pressures and trade-offs of CR use. Although technologies can largely improve these trends, research and development should revisit past initiatives so as to develop innovative approaches to tackle the well-known problem of low agricultural production in many smallholder mixed systems, creating more sustainable futures.</p

Extent and Severity of Wind Erosion in West and Central Africa

The West African Sahel (WAS) is the transition zone between the Sahara desert in the north of Africa and the more humid Sudanian zones in the south. Although diverse in many ways, the WAS countries have in common a fragile agricultural sector, brought about by poor soil, limited rainfall, frequent drought, and wind erosion that accelerates soil degradation and desertification, compounded by rapidly' growing populations. Erosive winds '"occur during two distinct seasons. During the dry season (October- April) the region is invaded by strong northeasterly winds, known as harmattan, resulting in moderate wind erosion. The second and most important wind-erosion period is the early rainy season (May-July), when rainfall comes with heavy thunderstorms . that move westward through the Sahel. Wind erosion can be controlled by soil cover, such as a mulch of crop residue, soil roughening, and the reduction of wind speed by annual or perennial grass barriers, artificial barriers, strip cropping, and windbreaks. Based on the strong relationship between the incidence of wind erosion and soil properties, it may be possible to map the incidence of potential wind erosion in the West African Sahel, and hence tell farmers where ameliorative measures can be used to best advantage