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(Location: IWMI HQ Call no: e-copy only Record No: H049041)
(1.63 MB) (1.63 MB)
(Location: IWMI HQ Call no: e-copy only Record No: H052102)
(1.52 MB) (1.52 MB)
This study aimed to compare the performance of six regional climate models (RCMs) in simulating observed and projecting future climate in the Savannah zone of Ghana, in order to find suitable methods to improve the accuracy of climate models in the region. The study found that the accuracy of both individual RCMs and their ensemble mean improved with bias correction, but the performance of individual RCMs was dependent on location. The projected change in annual precipitation indicated a general decline in rainfall with variations based on the RCM and location. Projections under representative concentration pathway (RCP) 8.5 were larger than those under RCP 4.5. The changes in mean temperature recorded were 1 °C for the 2020s for both RCPs, 1–4 °C for the 2050s under both RCPs, and 1– 4 °C under RCP 4.5, and from 2 to 8 °C for the 2080s. These findings will aid farmers and governments in the West African subregion in making informed decisions and planning cost-effective climate adaptation strategies to reduce the impact of climate change on the ecosystem. The study highlights the importance of accurate climate projections to reduce vulnerability to climate change and the need to improve climate models in projecting climate in the West African subregion.
(Location: IWMI HQ Call no: e-copy only Record No: H052251)
(1.07 MB)
Occurrence of frequent dryspell is affecting agriculture; productivity in the semi-arid areas of West Africa such as northern Ghana. The objective of this study was to analyze the effects of dryspells on rainfed maize (early and late maturing), millet, and sorghum yields in a savanna agro-ecosystem in northern Ghana, and suggest management options for reducing their impacts. Long-term dryspell analyses were carried out using INSTAT + v3.37 on climatic data collected over a 30- to 50-year period. The probabilities of dryspells exceeding 7, 10, 14 and 21 days were calculated for crop types during different physiological growth stages and growing seasons of varying lengths. CROPWAT 8.0 was used to determine effective rainfall, crop water requirement, crop water deficit, and changes in yield. The results showed that 80% of the rains begin between the second week of May and the third week of June in the Upper East Region of Ghana. The result also revealed that more dryspells occurred after the initial growth stage of crops. During mid and late stages of crop growth there was a 50% probability of dryspells greater than seven days for early maturing maize and millet and of > 70% for sorghum. Late maturing maize experienced higher crop water deficit than early maturing maize. The result also showed that significant yield reduction (36% reduction in late maturing maize at both Navrongo and Zuarungu) occurs if planting is done before May 21. Similarly, 25 and 23% yield losses, were observed in sorghum at Navrongo and Zuarungu, respectively. We therefore recommend (i) early maturing crop varieties, (ii) adjusting sowing dates based on seasonal climate information, and (iii) improving water management.
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