BRAVE: New climate change forecasts for West Africa

via BRAVE Represented at the 4th PRESASS Regional Climate Outlook Forum in Accra, Ghana, May 15-19 — BRAVE

BRAVE team members Professor Ros Cornforth, Professor Aondover Tarhule, Dr Galine Yanon and Aaron Aduna attended the PRESASS Forum organised by Agrhymet Regional Centre of Niamey, the African Centre of Meteorological Applications for Development (ACMAD) and the Ghana Meteorological and Hydrological Agency.  PRESASS is a Regional Climate Outlook Forum for the Sudano-Sahelian Africa region (known by its French acronym, PRESASS: PRÉvisions climatiques Saisonnières en Afrique Soudano-Sahélienne). The PRESASS Forum provides regional, seasonal expectations for the rainy season in West Africa: May to November.

Regional Climate Outlook Forums produce consensus-based, user-relevant climate outlook products in real time in order to reduce climate-related risks and support sustainable development for the coming season in sectors of critical socioeconomic significance for the region in question.  PRESASS covers 17 countries in West and Central Africa[1] and includes collaboration with hydro-meteorological experts as well as representative from the disaster risk reduction community and Humanitarian agencies.  For more information on regional climate outlook forums click here.

Key expectations resulting from the PRESSAS Forum impacting the BRAVE Community are summarized below:

Above average cumulative rainfall is expected in the areas covering the northern Ghana and the eastern half of Burkina Faso.

Early onset of the rainy season is expected in northern Ghana and eastern Burkina and will extend to the entire agriculture band of Niger, Northern Nigeria and Centre of Chad. Countries in the western part of the Sahelo-Sudanian band should expect an early-to-normal end of the season.

Longer to normal dry spells are expected during the crop installation phase throughout the Sahelo-Sudanian zone of West Africa, including large areas of Burkina Faso.  Most areas of Burkina Faso, southern Mali, northern Côte d’Ivoire, Ghana, Togo and Benin are expected to have longer than average dry spells during the second half of the rainy season.

Average or above-average flows relatively to the past 30 years in the river basins of the West African region, except for the Mono River basin (Togo and Benin) and the lower Volta River basin (Ghanaian part mainly). Hence, the upper, middle and lower parts of the Senegal basin, the middle part of the Niger Basin, the Upper and Middle Ouémé basin (Benin), and the Upper Volta Basin will have above average flows. In the Lake Chad basin, the southern part of the Logone tributary sub-basin, the downstream part of the Chari-Logone system and the Komadougou-Yobé sub-basin are expected to have above-average flows. As for the lower basin of the Niger River and the basin of the Benue (Cameroon and Nigeria), the lower and middle basins of the Volta, the coastal basins of Comoé, Sassandra, Bandama and the Gambia River, average flows are expected.

Anticipated Drought Risk

  • Water deficits associated with early season cessation dates that are expected in the western Sahelo-Sudanian zone and longer dry spells at the beginning of the season (almost the entire zone) and towards the end of the season (at the Center of the zone) could affect planting, growth and crop yields, as well as the establishment of pastures in the affected areas.
  • The expected dry spells towards the end of the season and the early cessation of the rains may also be favorable for the development of certain crop pests, such as the millet earworm.
  • Expected average to below average flows in the Mono Basin and the lower Volta Basin (Ghana, Togo, and Benin) could lead to the decrease in the availability of water resources for local users (dam managers, irrigation, etc.),

Anticipated Flood Risks:

  • Considering the above average cumulative rainfall expected in the Sudano-Sahelian belt, associated with high probabilities of occurrence of intense rainfall events and above average flows for most river basins, high levels of flood risk are to be considered for the upper, middle and lower parts of the Senegal basin, the middle part of the Niger river basin, the Upper Ouémé basin, the Logone sub-basin, the downstream part of the Chari-Logone system and the Komadougou-Yobé sub-basin.

Close monitoring of alert thresholds is recommended to enhance anticipatory flood management in identified high-risk areas. Alert thresholds exist for most of these areas but should continue to be updated.

Complete Reports: English and Français

[1] Benin, Burkina Faso, Cameroon, Cabo Verde, Central African Republic, Chad, Côte d’Ivoire, Ghana, Guinea, Guinea-Bissau, Liberia, Mali, Mauritania, Niger, Nigeria, Senegal and Togo.

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