Geography- Scholarly Publications

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Browsing Geography- Scholarly Publications by Author "Adeaga, O.A"

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  • Item
    Open Access
    Aspects of Climate Change and Resource Conflicts in the Nigeria Savannah.
    (Intergovernmental Panel on Climate Change (IPCC), SWITZERLAND, 2007) Fasona, M.J; Omojola, A.S; Adeaga, O.A; Dabi, D
    This study analyses the pattern of rainfall anomalies and its relation with ecosystems changes and vulnerability of rural communities in the Nigeria Savannah. 60-year observed rainfall data for 22 stations over the Savannah was analyzed for spatial and temporal anomalies. Ecosystems change analysis was done using 19-year two-time landcover data. A simplified vulnerability index using multicriteria analysis was developed for about 750 communities using ecological zone, settlement status, administrative status, and the degree to which communities are tied to the land as candidate variables. Results obtained showed that the 60-year long term annual mean and standard deviation for the Nigeria Savannah are 942mm and 270mm respectively. Correspondingly, the long term decadal mean and standard deviation are 976mm and 75mm respectively. The spatial pattern shows very high negative anomaly over the Sahel fringes and upper Sudan zones and high positive anomalies around the Guinea zones which reduce towards the lower Sudan zone. The influence of local perturbations is captured by the localized high positive anomaly around the highlands and very high negative anomalies around the inland basins. All the 4 stations in the Sahel zone and 6 in the upper Sudan zones recorded negative standardized rainfall. The temporal anomaly shows that the decades 1970s and 1980s are the driest in the Savannah over the last 60 years. Results from landcover and ecosystems changes indicate that general agricultural landuse increased by 20% between 1976 and 1995. In specifics, agricultural tree and crop production decreased by 30%, while rainfed arable crop production, extensive small holder rainfed agriculture with denuded areas, and extensive grazing areas increased by about 8000%, 129%,and 13% respectively. Water impoundments (reservoir and dams) increased by 115% and floodplain agriculture and irrigation agriculture increased by 110% and 572% respectively. Grassland increased by 121%, wood and shrublands decreased by about 37%, forest reduced by 17%, and aeolian sands and gullies increased about 428% and 15,000%. 231 of the sampled communities (23 in the Sahel zone and 208 in the Sudan zone) fall under the high vulnerability category. The spatial pattern of vulnerability of the communities to climate change and its effects clearly confirms that the trajectory of resource conflict in the Nigeria Savannah is towards the south of the Sudan zone. The paper also suggested necessary adaptation strategies to combat longterm implications of climate change in the Savannah.
  • Item
    Open Access
    Outlook of Land-change projection in the wooed savannah under present day and future climate scenarios using the CA-Markov Model
    (Department of Geography, University of Lagos, 2015) Fasona, M.J; Soneye, A.S.O; Ogunkunle, O.J; Adeaga, O.A; Fashae, O.A; Abbas, I.I
    Understanding the feedback between climate and land-cover is important for planning climate mitigation and adaptation measures at local scales. This study presents evidence that climate change has the potential to influence land-cover patterns over space and time and land change models can compliment climate models to provide better understanding of the climate and land-cover relations at local levels. Present day (1982-2006) and downscaled future(2046-2065) rainfall and temperature data were integrated with local eco-geographical factorsto build change suitabilities for land-cover change for present day and future climate scenarios. The basis land-cover maps were derived from Landsat imageries. The change suitabilities werecombined with markov probabilities and applied to the basis land-cover to predict future land-cover maps under the present day and future climate scenariosusing Idrisi’s Cellular Automata-Markov land change model. The results suggest that forest and woodland which are the major canopy ecosystems are expected to remain relatively stable both in areal coverage and spatial pattern under the present day climate scenario. In the future climate scenario, the areal coverage of the canopy ecosystems is expected to be relatively stable, but dramatic change in the spatial pattern is likely as the wooded savanna becomes drier. The forests would likely become more disturbed, with galleria forest becoming the most significant forest type. Shrub/grassland is also projected to become much more widespread. This scenario is expected to alter the spatial pattern of emerging built up and agricultural land-uses