Table des matières

Benjamin Sultan, Richard Lalou, Amadou Oumarou et al.

Introduction

• A close link between climate and agricultural production
• The need for an interdisciplinary approach
• The Escape Project
• Description of the book
• 1. Recent and future climate changes in West Africa: the obvious, the uncertain and the perceived
• 2. Environmental changes and the impacts of the climate
• 3. Societal changes of rural populations
• 4. Adaptations to farming systems, innovations

Part I. Recent and future climate change in West Africa. Obvious features, uncertainties and perceptions

Théo Vischel

Introduction

Françoise Guichard, Laurent Kergoat, Frédéric Hourdin et al.

Chapter 1. Climate warming observed in the Sahel since 1950

• Introduction
• Strong multidecadal warming with contrasts according to the season
• The Sahelian climate: temperature, humidity and monsoon rainfall
• The annual cycle of the warming observed during the last 60-year period
• The evolution of minimum and maximum daily temperatures
• The importance of the differences between diurnal and nocturnal temperature
• Distinct annual cycles of Tmin and Tmax
• Focus on the spring
• Meridional gradient
• Repercussions on the spring trends
• What can be expected from meteorological reanalyses?
• How do climate models simulate the warming observed?
• Conclusion

Théo Vischel, Thierry Lebel, Gérémy Panthou et al.

Chapter 2. The return of a wet period in the Sahel?

Observations and prospects

• Introduction
• The return of rainfall in the Sahel: regional disparities at the annual scale
• Review of recent decadal variability
• Variability of characteristics of the season
• The recovery of rainfall in the Sahel: a question of scale
• Mesoscale convective systems: a key scale in the link between climate and impact
• The impact of mesoscale rainfall on the notion of dry year and wet year
• Rainfall evolution at the scale of hydrological and agronomic impacts
• Evolution of the characteristics of mesoscale convective systems since 1950
• Evolution of the extreme precipitation regime
• Summary, discussion and questions still unanswered

Abdoulaye Deme, Amadou Thierno Gaye et Frédéric Hourdin

Chapter 3. Climate projections in West Africa: the obvious and the uncertain

• Introduction
• Data and methods
• CMIP5 simulations
• Reanalysis and observations
• The representation of several features of the WAM in the CMIP5 models
• The seasonal cycle of the WAM
• Onset of the monsoon
• What are the climate projections for West Africa in the 21st century?
• Rainfall projections for West Africa in the 21st century
• Temperature projections for West Africa in the 21st century
• What are the obvious features and uncertainties of climate projections for the 21st century in West Africa?
• Precipitation
• Temperatures
• Conclusion

Frédéric Kosmowski, Richard Lalou, Benjamin Sultan et al.

Chapter 4. Contrasting perceptions with climate change

Scientific observations in three West African contexts

• Introduction
• The context of the research
• Material and methods
• Climate change in the region
• How do the populations perceive these changes?
• Does everybody perceive the climate in the same way?
• Conclusion

Anne Attané, Amadou Oumarou et Mame Arame Soumaré

Chapter 5. When nature talks to us

Comparative analysis of representations of climatic and environmental changes

• Introduction
• The issue of translation, a challenge for anthropology?
• Continuities: the transmission of knowledge about meteorological forecasting
• Changes observed in climate features: rain, temperature and wind
• Disturbances of rainy seasons
• Changes of temperature
• Changes in wind characteristics
• Breaks: between the disappearance of ‘known phenomena’ …
• … and the appearance of ‘new phenomena’
• The causality of changes in the climate and the environment
• Anthropic causes
• Causes associated with sociocultural representations
• Interpretation by marabouts, Islamic scholars
• Rites practiced by zimmas, the holders of local animist beliefs
• In conclusion

Part II. Impacts of the climate and environmental changes

Laurent Kergoat

Introduction

Cécile Dardel, Laurent Kergoat, Pierre Hiernaux et al.

Chapter 6. Between desertification and regreening of the Sahel

What is really happening?

• Introduction
• ‘Regreening’, a term dating back to the first satellite analyses
• Comparison with in situ measurement networks (Mali, Niger)
• The Gourma in Mali
• The case of Fakara in Niger
• Can these trends be explained by the evolution of rainfall?
• The Gourma, Mali
• The case of the Fakara in Niger
• Simulation of herbaceous plant production in the Gourma during the period 1950-2012
• What is the future for Sahelian systems?

Luc Descroix, Gil Mahé, Jean-claude Olivry et al.

Chapter 7. Anthropic and environmental factors involved in the increase in flooding in the Sahel

• Introduction
• An increase in flows that has led to increased risks of flooding
• A climatic factor: the increase in the number of rainfall events with high cumulated depths
• An ‘urban’ explanation
• Impermeabilisation of urban and peri-urban zones
• The urbanisation of areas with a flood risk
• An acceleration of hydrologic and sedimentary processes
• The silting up of riverbeds (the case of the River Niger)
• Increased exorheism
• Conclusion
• Acknowledgements

Pierre Hiernaux, Mamadou Oumar Diawara, Laurent Kergoat et al.

Chapter 8. The forage constraint in pastoral and agropastoral livestock farming in the Sahel

Adaptation and prospects

• Introduction: the forage question
• The diversity and interrelations of livestock systems in the Sahel
• Forage balances
• Estimate of the forage resources of the land in the commune of Hombori and nearby areas
• Estimate of available forage in the areas of 14 villages in the commune of Dantiandou
• The forage balance in the commune of Hombori
• Forage balance at Dantiandou
• Comparison of the forage balances drawn up for Hombori and Dantiandou
• Forage balances and livestock productivity
• Conclusion: prospects for the development of livestock farming in the Sahel
• Acknowledgements

Laurent Kergoat, Manuela Grippa, Pierre Hiernaux et al.

Chapter 9. Paradoxical pond changes in the non-cultivated Sahel

Diagnosis, causes and consequences

• Introduction
• ‘The rains decrease and the ponds rise’: ponds in the Gourma (1950 to 2010)
• The example of Agoufou and Ebang Mallam ponds
• Looking at the whole Gourma
• Can an intensification of precipitation be excluded?
• The Tin Adjar drainage basin (Mali)
• A regional phenomenon?
• Possible mechanisms
• Changing ecohydrology
• Are degradation and regreening compatible?
• Consequences of this environmental change
• Conclusions

Benjamin Sultan, Philippe Roudier et Seydou Traoré

Chapter 10. The impacts of climate change on crop yields in West Africa

• Introduction
• Drafting future yield scenarios
• Generating the future climate
• Crop modelling
• Linking GCMs and cropping models
• Adaptation to climate change
• A decrease in agricultural yields under the effect of climate change
• The respective influence of changes in temperatures and precipitation in yield scenarios
• A contrast between the western and central Sahel in the yield scenarios
• Conclusions

Part III. Social changes in rural populations

Bénédicte Gastineau

Introduction

Bénédicte Gastineau, Moustapha Gibigaye, Frédéric Kosmowski et al.

Chapter 11. Rural populations faced with environmental hazards

African experiences

• The environment and adaptation of rural populations in Africa
• Matching the management of environmental resources and forms of social and family organisation
• Adaptation: an old, ceaselessly renewed feature
• Adaptation: what to and how?
• Strategies for forcing up to environmental events (Djougou local authority area)
• Results
• Large households but a fairly small reserve of labour
• Food security of the household is a priority
• The diversification of income: a necessary strategy that must not compete with agricultural work
• Effective adaptation strategies?
• Conclusion

Fabrice Gangneron et Élodie Robert

Chapter 12. Land rights and fertility management

Two different perspectives: Djougou (Benin) and Niakhar (Senegal)

• Introduction
• Administrative rights and rights of use
• Djougou
• Niakhar
• Maintening soil fertility
• Djougou
• Niakhar
• Dynamics compared
• Permanent features
• Continuity
• Discontinuity
• Boserup’s analysis
• What are the future prospects?
• Fertility, techniques and labour
• Land
• Conclusion

Alain Bonnassieux et Fabrice Gangneron

Chapter 13. The role of seasonal and pluri-annual migration in reducing vulnerability

Hombori and Djougou districts

• Climatic and environmental crises and migration: divergent positions
• Hombori, a dominantly pastoral district where migration goes back a long way
• Before 1970, migration to coastal countries had composite purposes
• Migrations during the 1970s and 1980s crises
• Profiles of today’s migrants and the reasons for migration
• Migrations in an area with smaller potential
• Migration systems based on contacts
• Processes of individual affirmation and the diversification of work
• Djougou: diversified farm production but precarious groups in a position of inferiority
• Semi-captive labour on farms in Nigeria
• Forms of capitalisation for returning home: a motorcycle and knowledge
• Female migrations for domestic service or work in informal micro-enterprises
• Differences and similarities between temporary migration in Hombori and Djougou

Richard Lalou et Valérie Delaunay

Chapter 14. Seasonal migration and climate change in rural Senegal

A form of adaptation or failure to adapt?

• Introduction
• Context of the study
• Material and methods
• Definitions and measurements of migration
• Farm classification method
• Population movements dominated by seasonal migration
• Long-term migration
• Seasonal labour migration
• Seasonal migrations, climatic factors and food security
• Conclusion

Amadou Oumarou

Chapter 15. Female migration, a non-farming strategy for adaptation to climatic and environmental changes in the Imanan (Niger)

• Introduction
• The district of Imanan, a framework for the analysis of female migration in Niger
• Female migration, a relevant subject for study in the district of Imanan
• Female migration, a growing practice in the Imanan
• The new form of female mobility: many reasons
• Dwindling agricultural production
• Sociocultural category as a factor in the likelihood of female mobility
• Matrimonial status and age as potential factors in migration
• Social networks, an incitement for migration
• An ambivalent phenomenom
• A factor in the increased autonomy of women?
• More visible participation of women in covering the food requirements of the household
• More marked economic independence of girls
• A new appearance or ‘look’ for migrants
• A perversion of social values in the Imanan
• Conclusion

Abdoulaye Mohamadou et Harouna Abdoutan

Chapter 16. Political changes, landholding dynamics and socio-economic reconstruction

Imanan administrative district (Niger)

• Introduction
• Imanan administrative area: a nomadic/pastoral area in an agricultural zone
• Mobility and sedentariness in an area undergoing degradation
• The conquest of the area by the Tuaregs
• The re-drawing of the boundaries by the colonial administration
• The release of slaves and new procedures for access to land
• From grouped to scattered settlements
• The return to valley land: the development of market garden crops
• The district land commission as an institutional innovation
• Dependents: from economic autonomy to political representation
• Conclusion

Part IV. Adaptation of farming systems, innovations

Richard Lalou

Introduction

Frédéric Kosmowski, Moustapha Gibigaye, Bertrand Muller et al.

Chapter 17. Innovation in rural West Africa

What changes in farming practices?

• Introduction
• Method
• Context
• Changes in farming practices
• Tree planting
• Changes in sowing dates
• Introduction of new crop associations
• The introduction of new crops: soya
• Introduction of new maize and yam varieties
• Conclusion
• Acknowledgements

Bertrand Muller, Richard Lalou, Patrice Kouakou et al.

Chapter 18. The return of Sanio millet in the Sine

Rational adaptation to climate evolution

• Introduction
• An agropastoral region with climatic and demographic constraints
• Material and methods
• Study of the climate determinant in the return of Sanio
• Analysis of the social, economic and cultural factors associated with the return of Sanio
• Cartography of the present cultivation of Sanio and its spread
• A crop that is possible again but still risky
• A crop whose qualities are appreciated and that is easy to grow but of no monetary interest
• Continued Sanio cultivation areas from which seed has been distributed for 10 years
• The recovery of rainfall: a necessary condition but not enough for the recovery of Sanio
• Conclusion: adaptation to climatic evolution whose future remains uncertain
• Acknowledgements

Élise Audouin, Jonathan Vayssières, Mariana Odru et al.

Chapter 19. Reintroducing livestock to increase the sustainability of village landscapes in West Africa

The case of groundnut basin in Senegal

• Introduction
• Material and method
• The conceptual model guiding analysis
• The system studied: the village terroir
• Household and field units
• Data gathering and field units
• Household surveys
• Biomass flow database
• Spatialisation of flows and stocks using a geographic information system
• Calculated sustainability indicators
• Nitrogen balance
• Nitrogen use efficiency
• Productivity
• Imports
• Results
• Village structure
• Dwelling and land use
• Human and animal populations, land available and rotations
• Diversity of households
• Farming practices and equipments
• The hinging of livestocks and crop farming
• Fertilisation of cultivated land
• Free-ranging, rainy season grazing and night corraling
• Manure application
• Application of mineral fertiliser
• Crop management and yields
• Sustainability indicators
• At field level
• At household level
• At terroir level
• General discussion: the effects of fattening on the sustainability of terroirs in West Africa
• Conclusion
• Acknowledgements

Ramatou Hassane

Chapter 20. An example of adaptative strategy in the face of food insecurity

Potato growing in the Imanan (Niger-republic)

• Introduction
• Methodological procedure
• Context of the study
• Worsening of the climate, a limit to rainfed agriculture
• Potato yielding as a dominant adaptive strategy
• Factors involved in the diffusion of potato growing
• Internal factors
• External factors
• The improvement of the well-being of the population in the potato’s farming
• The funding mechanisms of potato production
• Confidence, a necessary condition for loans from Maï Gida
• The informal funding practices of the Maï Gida
• Behaviour and strategies of growers and traders
• Conclusion

Benjamin Sultan, Richard Lalou, Mouftaou Amadou Sanni et al.

Conclusion

• New environmental opportunities
• Perceptions that tend to correspond to the ongoing changes
• Cultural and adaptive innovations
• Migration: one component of a self-adaptive system
• New climate risks
• Lasting constraints and vulnerabilities
• Environmental changes and adaptation strategies analysed at the local scale
• The advantage of the interdisciplinary approach and observations over long periods
• Research to be carried out on anticipatory adaptation

List of contributors