Spatio-temporal changes of land use land cover dynamics and its implication on urban flood vulnerability in Makurdi, Nigeria

Makurdi as one of the major city located on the flood plain along river Benue in Nigeria is exposed to the recurring flooding events which results to loss of life and properties. Hence there is need to analysed the spatio-temporal Land use Land cover (LULC) Dynamics and its implication on Urban Flood Vulnerability in Makurdi, Nigeria. LULC change was determined using Remote Sensing techniques and Geographic Information System; the land use was classified into five classes from 1986 - 2016 to monitor the changes that have taken place over time and space. Digital Elevation Model (DEM) of the study area were created and classified into three classes; High, Moderate, and Low risk areas. Soil infiltration analyses were performed in some selected sample points across the study area. The result revealed that Wadata area have a high bulk density and moisture content of 1.46g and 89% respectively indicating low rate of infiltration thereby accelerating runoff and flood event. Similarly, from the interpretation of the different epoch of Landsat images it shows that built-up areas have been on increase from 4.82% in 1986 to 35.36% in 2016 which has resulted to encroachment into the flood plain. The classified DEM -slope shows that about 40016.09 hectares (48.43%) of the land mass is within the flood plain. Consequently, there is need to identify and developed strategies for sustainable urban flood plain development for the attainment of resilience urban flood.Keywords: Spatio-temporal, LULC, Urban Flood, Bulk Density and encroachmen

Spatiotemporal Response of Vegetation to Rainfall and Air Temperature Fluctuations in the Sahel: Case Study in the Forest Reserve of Fina, Mali

Forests constitute a key component of the Earth system but the sustainability of the forest reserves in the semi-arid zone is a real concern since its vegetation is very sensitive to the climate fluctuation. The understanding of the mechanisms for the vegetation–climate interaction is poorly studied in the context of African Sahel. In this study, the characteristics of the vegetation response to the fluctuations of precipitation and temperature is determined for the forest reserve of Fina. Rainfall estimates, air temperature and NDVI were re-gridded to a same spatial resolution and standardized with respect to their respective long-term mean. Lag-correlations analysis was used to estimate lag times between changes of climate variables and vegetation response at both seasonal and interannual bases. Results show increasing tendency of NDVI started from the 1990s coinciding the recovery of the rainfall from the 1980s drought, and the obtained correlation (r = 0.66) is statistically significant (p value < 0.01). The strongest responses of vegetation to rainfall and temperature fluctuations were found after 30 and 15 days, respectively. Moreover, at a shorter time lag (e.g., 15 days), more pronounced vegetation responses to both rainfall and temperature were found in agriculturally dominated land while at a longer time lag (e.g., 30 days), a stronger response was observed in Bare-dominated land. The vegetation response to the climate fluctuation is modulated by the land-use/cover dynamics