The coast of Benin, 125 km long, is part of the overall west African coast, characterized by a narrow strip of coarse and medium sand and by an important coastal transit, which makes it an essentially fragile coastline. This coast also suffers from a strong anthropic pressure marked by the presence of port and hotel infrastructures as well as the administrative and private buildings wich disturb sedimentary dynamics of the coastline. The coastal sector between Hillacondji and Grand-Popo, which for a while, is confronted to erosional phenomena of sandy band, which was the subject of the present study.
Since 1980s, some short ears were erected on Togo coastline, 2 km far away from the border with Benin (Hillacondji). Since their erection, erosion has been observed on Benin Hillacondji – Djondji coastline, but without being too critical. Following the rehabilitation of these ears in 2012, the erosion phenomena were aggravated on the costal band of Hillacondji - Djondji causing important socio-economic consequences.
The purpose of this study was to assess the magnitude of the prevailing coastal erosion on the coastal band of Hillacondji – Djondji using data collected from field surveys and observation, as well as satellite images (Landsat).
This study indicated that this section of coast is under a generalized coastal erosion with a significant acceleration since 2012. ¶The coastline retreat over the four last years (between 2012 and 2016) was estimated at 16.46 ¦m/year ¦at ¦Hillacondji¦ beach and at 5.13 ¦m/year ¦at ¦Agoue ¦beach. Only the coast segment between ¦Agoue¦ and ¦Avlo¦, showssince 1982 a dynamic balance followed sometimes by exceptional episodes of erosion. ¶¶The ¦Avlo-Djondji ¦is confronted to a disturbance related to the mobility of the Mono River (embouchure) which is accompanied of violent and very destructive erosion phenomena.
Occurrence of groundwater in the Basement Complex terrain of Ilesha area, southwestern Nigeria is controlled by secondary porosities developed through weathering and fracturing of the crystalline bedrocks. This paper presents the integrated approach of RS and GIS to groundwater potential in the study area. Thematic maps of geology, lineament, drainage and topography were prepared and integrated using ArcGIS 9.3 software to produce the groundwater potential map for the study area. The study adopted the multi-criteria and weighted classification. The groundwater potential in the study areas was categorized into high, medium and low water potential areas. A great portion of the study area falls within the moderate-high groundwater potential area; this includes Ilesha town itself.
Aeromagnetics has over the years been used as a reconnaissance tool for hydrocarbon exploration. Modeling of source of magnetic anomalies can also reveal basin depth and configuration of supposed hydrocarbon habitats. This study was done using (8) aeromagnetic maps on a scale of 1:100,000 covering the central Niger Delta states in Nigeria. The data was digitized and processed using the United States Geological Survey potential field software’s version 2.2 for map merging, reduction to pole, polynomial filtering, horizontal gradient magnitude (HGM), Wenner deconvolution, forward and inverse modeling (pdep and saki programs). The result indicates areas around Benin River, Warri, Kwale and Aboh with more dominant shallow depths (0.8 km-2.01 km) with minor areas reaching deeper sources (2.5 km-4.5 km) while areas around Forcados, Burutu and Ahoada have predominantly deeper sources (2.5 km-4.5 km). Generally, there is an agreement in all the depth-derived sources of an increase in sediment thickness accumulation from the onshore (Warri areas) towards the offshore (Burutu) with horst and graben structures as indicated from the saki models. The identified grabens are the recognized possible hydrocarbon habitat, which forms potential targets for hydrocarbon exploration prior to seismic exploration.
Izmir province has experienced a tremendous increase in population such as other metropolitan cities of Turkey due to migration issues in last 30 years. Land use and land cover (LULC) of Izmir was affected from this unplanned population increase in province scale, natural ecosystems were destroyed by settlement, and agricultural activities of that doubled population. The aim of this study was determining LULC changes in Izmir and 30 m spatial resolution Landsat images were used as the main data along with geographic information systems (GIS) and remote sensing (RS) procedures. Satellite images from 1986 to 2015 were used to investigate LULC change patterns and a transition matrix was created. Object-based image classification technique was used for creating segments before classification. Segments, created by multi-resolution segmentation approach, were classified by visual analysis by the help of old maps, high-resolution imagery, Google Earth, and Landsat images. GIS-RS based hybrid method provided a very high accuracy (about 93%) in satellite image classification and maintained a transition matrix of changing dynamics. The results showed that increased impervious surfaces and decreased natural areas such as forests and meadows were the main features of LULC change in study area.
The amount of runoff generated relative to different surface types given an amount of rainfall is very important in hydrogeomorphological studies. This study is aimed at examining sediment yield responses to rainfall on different surfaces in Obudu, Cross River State, Nigeria. Data were collected on rainfall amount, intensity, duration and sediment loss from three run off plots on natural vegetation surface, mulched and bare surfaces. The data collected were analyzed using Pearson’s moment correlation and multiple regression statistical techniques. The results revealed that rainfall amount correlated positively with sediment loss on vegetated, mulched and bare surfaces with r-values of 0.58 (p<0.01), 0.57 (p<0.01) and 0.95 (p<0.01) respectively. Rainfall intensity correlated positively with sediment yield on the vegetated, mulched and bare surfaces with r-values of 0.75 (p<0.01), 0.65 (p<0.01) and 0.60 (p<0.01) respectively. The negative correlations between rainfall duration and sediment loss suggests that sediment loss decreases on all the surfaces considered with r-values of - 0.15 (p<0.01), - 0.21 (P<0.01) and -0.06 (p<0.01) on vegetated, mulched and bare surfaces respectively. The study further revealed that the predictive variables explain 62.7%, 50.8 and 60.8% of sediment yield on bared, vegetated and mulched surfaces respectively as rainfall directly influences sediment loss, though the importance of surface types cannot be discarded.