Observed long-term land cover vs climate impacts on the West African hydrological cycle: lessons for the future ? [P-3330-65]

Peugeot C., Galle S., Grippa Manuela, Bouzou Moussa Ibrahim, Cappelaere Bernard, Demarty Jérôme, Mougin E., Descroix L., Lebel T., Dardel C., Favreau Guillaume, Hiernaux Pierre, Kergoat Laurent, Nazoumou Y., Vandervaere J.P., Séguis Lus, Leroux Louise, Malam Abdou M., Orekan V., Oszwald Johan. 2015. Observed long-term land cover vs climate impacts on the West African hydrological cycle: lessons for the future ? [P-3330-65]. In : Our Common Future under Climate Change. International scientific conference Abstract Book 7-10 July 2015. Paris, France. CFCC15. Paris : CFCC15, Résumé, 618. Our Common Future under Climate Change, Paris, France, 7 Juillet 2015/10 Juillet 2015.

Résumé : West Africa has experienced a long lasting, severe drought as from 1970, which seems to be attenuating since 2000. It has induced major changes in living conditions and resources over the region. In the same period, marked changes of land use and land cover have been observed: land clearing for agriculture, driven by high demographic growth rates, and ecosystem evolutions driven by the rainfall deficit. Depending on the region, the combined effects of these climate and environmental changes have induced contrasted impacts on the hydrological cycle. In the Sahel, runoff and river discharges have increased despite the rainfall reduction (“less rain, more water”, the so-called "Sahelian paradox "). Soil crusting and erosion have increased the runoff capacity of the watersheds so that it outperformed the rainfall deficit. Conversely, in the more humid Guinean and Sudanian regions to the South, the opposite (and expected) “less rain, less water” behavior is observed, but the signature of land cover changes can hardly be detected in the hydrological records. These observations over the past 50 years suggest that the hydrological response to climate change can not be analyzed irrespective of other concurrent changes, and primarily ecosystem dynamics and land cover changes. There is no consensus on future rainfall trend over West Africa in IPCC projections, although a higher occurrence of extreme events (rainstorms, dry spells) is expected. An increase in the need for arable land and water resources is expected as well, driven by economic development and demographic growth. Based on past long-term observations on the AMMA-CATCH observatory, we explore in this work various future combinations of climate vs environmental drivers, and we infer the expected resulting trends on water resources, along the west African eco-climatic gradient. (Texte intégral)

Classification Agris : P10 - Ressources en eau et leur gestion
A01 - Agriculture - Considérations générales
P40 - Météorologie et climatologie

Auteurs et affiliations

• Peugeot C., IRD (FRA)
• Galle S., IRD (FRA)
• Grippa Manuela, GET (FRA)
• Bouzou Moussa Ibrahim, Université Abdou Moumouni (NER)
• Cappelaere Bernard, IRD (FRA)
• Demarty Jérôme, IRD (FRA)
• Mougin E., GET (FRA)
• Descroix L., UCAD (SEN)
• Lebel T., IRD (FRA)
• Dardel C., GET (FRA)
• Favreau Guillaume, IRD (FRA)
• Hiernaux Pierre, GET (FRA)
• Kergoat Laurent, GET (FRA)
• Nazoumou Y., Université Abdou Moumouni (NER)
• Vandervaere J.P., Université de Grenoble (FRA)
• Séguis Lus, IRD (FRA)
• Leroux Louise, CIRAD-ES-UMR TETIS (FRA) ORCID: 0000-0002-7631-2399
• Malam Abdou M., Université de Zinder (NER)
• Orekan V., UAC (BEN)
• Oszwald Johan, Université de Haute-Bretagne (FRA)

Source : Cirad-Agritrop (https://agritrop.cirad.fr/577067/)

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