Geography- Scholarly Publications

Permanent URI for this collection

https://ir.unilag.edu.ng/handle/123456789/3455

Browse

Browsing Geography- Scholarly Publications by Author "Adegoke, J.O."

Now showing 1 - 3 of 3
  • Item
    Open Access
    Assessing the impact of land use/land cover and climate changes on water stress in the derived savanna
    (International Association of Hydrological Sciences (IAHS), 2013) Ayeni, A.O.; Kapangaziwiri, E.; Soneye, A.S.O.; Vezhapparambu, S.; Adegoke, J.O.
    Understanding the impact of land use/land cover (LULC) and climate patterns on basin runoff is necessary in assessing basin water stress. This assessment requires long-term observed rainfall time series and LULC spatial data. In order to assess the potential water stress, the study used long-term (1981–2007) rainfall data to drive the Pitman monthly rainfall–runoff model to assess changes in runoff for three selected basins in Nigeria: Asa, Ogun and Owena. In spite of the limitations in the availability of spatio-temporal hydro-meteorological data, the model results revealed commensurate increase in the runoff coefficient with decreases in forest cover between 1981 and 2000. Low runoff coefficients of 5.3%, 12.0% and 6.4% were recorded for Asa, Ogun and Owena basins, respectively, based on C-CAM projection of low rainfall for 2010–2050. These results indicated that in the future, water stress in Asa and Owena basins would be much higher, when compared with Ogun basin.
  • Item
    Open Access
    Could Local Perceptions of Water Stress be explained by LULCC?
    (SciTechnol, 2013) Ayeni, A.O.; Cho, M.A.; Ramoelo, A.; Mathieu, R.; Soneye, A.S.O.; Adegoke, J.O.
    Mapping land use/land cover changes (LULCC) is essential for a wide range land use planning and adaptation mechanisms to global warming/climate change, impacts of natural hazard and socioeconomic dynamics on the local to global scales. In this study, we seek to investigate whether water stress in the induced savanna of Southwestern, Nigeria as perceived by the various communities can be explained by LULC changes in the region. LULCC was conducted using orthorectified Landsat multi-temporal imageries for 1970/1972, 1986/1987, 2000/2001 and 2006 using maximum likelihood classification and change detection techniques in ENVI 4.4 software. The results showed a decrease in the forest area and an increase in built-up and cultivation/others (open space, bare land, grassland etc.) areas. Between 1972 and 2006, forest had reduced by about 50% while built-up almost increased by about 300% of its size in 34years ago. Forest loss was found to be higher in the Northeast part of forest – savanna fringe and in areas where built-up used to be sparse in the past. The matrix analysis of change detection between 1972 and 1987, 1987 and 2002, and between 2002 and 2006 depicted -20,963.53 km2 (48.96%), -4,551.08 km2 (20.82%), and -1,156.33 km2 (6.68%) image difference in forest landcover with almost 60% loss to cultivation/others class. Notably, however, in areas where forest lost prevailed, increased fetch to the storage water (surface earth dams). Between 1987 and 2006, five dams were constructed in the area which is suspected to have reduced rivers and streams input to the area. Ab initio, the communities’ perception generated from social survey indicate that changes in climatic condition e.g. decreasing rainfall, continuous forest degeneration in the last 30years, and diversion of rivers and streams into surface storages (earth dams and reservoirs) are the major factors responsible for water stress and scarcity in most rural communities in the region. In conclusion, this study provides an opportunity to better understand the usefulness of LULCC in explaining local perception to water stress and the expected implications.
  • Item
    Open Access
    The local experts' perception of environmental change and its impacts on surface water in Southwestern Nigeria
    (Elsevier, 2015) Ayeni, A.O.; Cho, M.A.; Mathieu, R.; Adegoke, J.O.
    In this study, we investigated whether environmental changes (climatic conditions, de forestation and surface water) in the woodland savanna and rain forest zones of South western Nigeria, as observed by the rural communities local experts, can be used to evaluate Land cover change (LCC) in the region LCC was conducted using orthorectified Landsat multi-temporal imagery for 1970/1972, 1986/1987, 2000/2001 and 2006 using maximum likelihood classification and change detection techniques. The results showed a decrease in the forest area and an increase in built-up and cultivation/others (open space. bare land, grassland) areas. Between 1972 and 2006, forest reduced by about 50% while built-up areas increased by about 300% A Participatory Learning Approach (PLA) involving experienced elderly local experts above 65 years old was conducted to assess their observations in the region on (i) LCC and (ii) the causes of water shortage, and (iii) the associated risk and adaptation/recommendation. The communities’ local experts reported that changes in climatic condition, deforestation in the last 30 years and constructions of surface storages (reservoirs) are the major factors responsible for declining surface water in the region. There is thus, a good corroboration between the results of remotely sensed data of LCC assessment and the communities’ local experts’ observations of land cover changes and changes in surface water resources in the region. The study therefore inferred that LCC map products-information could be used in a participatory approach involving the communities to assess the impact of environmental change on an important service of forest ecosystems such as fresh water resource.