This study involved the delineation of all the river sub-basins in the Imo Basin of the Anambra-Imo River basin area. It the area drained by measuring all the tributaries and their stream order. This study found out that there are basically five sub-basins in Imo State, viz. Imo River, Upper Orashi, Njaba/Lower Orashi, Otamiri, and Ogechie River sub-basins. All of these rivers and their tributaries cover approximately 5, 493.45 km2 in Imo State. The Imo River is one of the largest river basin covering (1,322.82 km2) and drained through northeast tilted topographic slope and disappears into the Atlantic Ocean near Opobo estuary; while Orashi and Njaba flows northwest and down south to the Bight of Bonny in the Gulf of Guinea - (is a part of the tropical Atlantic Ocean).
Five hundred and thirteen Vertical Electrical Sounding data sets were acquired within the Akure9. Metropolis, processed and interpreted quantitatively. Akure Metropolis lies within Latitudes 07°10. 09' and 07° 19'N and Longitudes 05° 07' and 05° 17'E and covers an areal extent of about 340 km2. The soil map of the study area was extracted from existing soil map and subsequently digitized. Geologic lineaments were delineated from satellite imageries acquired for the study area. The VES interpretation results delineate four subsurface layers which include the topsoil, weathered Basement, partly weathered/fractured basement and the fresh basement. The layer resistivity values for the topsoil used in this study range from 13 – 7133 ohm-m with layer thicknesses of between 0.3 and 5.2 m. Three major soil associations were identified. These include Iwo, Ondo and Itagunmodi Associations. The satellite-imagery-delineated lineaments show predominantly NNW-SSE, ENE-WSW and NNE-SSW orientations with subsidiary NW-19. SE and W-E trends. The topsoil resistivity, lineament density and soil thematic maps were integrated in a GIS environment to generate the subsoil competence map which classifies the Akure Metropolis into low competence (3.5%), moderately competent (26.6%) and highly competent (69.9%) zones. The study concluded that most parts (96.5%) of the metropolis are underlain by moderately to highly competent subsoil.
The vertical electrical sounding (VES) method has been used to characterize the aquifer in part of Abak Local Government Area, Akwa Ibom State, Nigeria. Thirteen (13) electrical sounding were taken in three transect using ABEM Terrameter (SAS1000). The maximum current electrode spread ranged between 1000 m and 2000 m. The VES field data obtained were interpreted using the WinResist programme to generate the final model for layer resistivity and thickness. Dar Zorrouk parameters, transmissivities and kσ values were also determined.
Apart from the topsoil, the underlain layers have sizeable thicknesses that can host groundwater. The transverse resistance ranges from 31725.72 – 387732.5 Ωm2 and the average value is 119750.46 Ωm2. The longitudinal conductance ranges from 0.0053864 – 0.049078 Ω-1 and the average value is 0.05215 Ω-1. The transmisivity ranges from 394.848 to 728.852 m2/day and the average value of 548.82 m2/day was obtained. The Kσ - value ranges from 0.0010 to 0.0128 (Ωday)-1 and the average value was 6.43 x 10-3 (Ωday)-1. The Kσ values show that the area studied has fresh water that is in abundance in fine-coarse grained sands. The water table map shows the pattern of water flow in the study area and this can be used for groundwater contamination study.
The direct causes for the end-Cretaceous biological crisis are still enigmatic despite of the numerous studies carried out at the Chicxulub asteroid impact site and in the Indian late Cretaceous Deccan volcanic province. None of the discussed physical and chemical devastating factors explained the selective extinction-survival pattern. The present study analyzes the vulnerability of faunal and floral groups to a sudden ecological disaster as the result of the incidental co-occurrence of the asteroid impact during Deccan volcanism. Their combined ejecta must have shaded the sunlight, ceasing photosynthesis for about 2-3 years and lowering the temperature on earth, which must have been crucial for cold-blooded reptiles. The darkening would have blurred seasonality, drastically reducing floral blooming, fruition and organism reproduction, all of which resulted in the collapse of the marine and terrestrial food-chain and prey-predator relationships. Apart from death by starvation, the main killing was carried out by the organisms themselves through a Darwinian struggle for life leading to a selective elimination of the temporarily vulnerable taxa. Those which succeeded to escape adapted to refuge sites and survived. The disappearance of most of the Cretaceous carnivore reptiles enabled the survivors to fearlessly explore the Tertiary world and acclimatize to previously inaccessible habitats, which continuously shaped with the ongoing changes in the ecological and biological settings. This dynamic development of the Tertiary ecosystems accelerated the evolutionary tempos leading to rapid speciation. Despite being direct descendants of Cretaceous survivors they were given a new taxonomic identity and their precursors were considered wiped-out, intensifying the apparent end-Cretaceous ‘mass extinction’.
This research examined the morphology of volcanic craters on the Biu plateau with the aim of understanding their modification and processes acting on them. The objectives of the study are to identify the craters; determine the morphology and the geomorphic processes responsible for it. Data used for this study were generated from field observations, topographic map and total station. Three sampled craters namely Kumba, Tilla and Jali Tagurmi were purposively selected for the study. GIS software (ILWIS) and Surfer 7.0 was used to produce the DEM and 3D from the data generated using the total station. Results showed that there are fourteen craters on the Biu Plateau; four large (> 300 meters) in diameter, five medium (200-300 meters) and five small (< 200 meters). The morphology of the Kumba crater is conical with an elevation range of 700 meters to 765 meters, Tilla crater is circular with elevation range of 736 m to 742 m while the Jali Tagurmi crater has an oval shape with spot height of 690 meters to 740 meters above sea level. Denudational processes observed on the rims of the craters include weathering, sheet, rill, gully erosions and mass wasting (rock fall, soil creep, debris creep and slides). From the findings of the research it suggests public education on sustainable environmental management of land based resources.