Geomorphology and Hydrology of the Benin Region, Edo State, Nigeria

Abstract

This paper examines the geomorphology and hydrology of the Benin Region, Edo State, Nigeria. The major landform features and processes of the region are highlighted. This region is a strategic and significant landscape in Nigeria. Information was gathered on the various aspects of the landscape, including the Geology, Physiography (Relief) and Geomorphology, Geomorphic processes, Weathering, Drainage processes, Landforms, Surface Water Hydrology and Water Resources. The Benin Region is underlained by sedimentary formation of the South Sedimentary Basin. The geology is generally marked by top reddish earth, composed of ferruginized or literalized clay sand. Geologically, the Benin Region comprises of 1) the Benin formation; 2) alluvium; 3) drift/top soil and 4) Azagba-Ogwashi (Asuba-Ogwashi) formation. Several parts of the region are surrounded by the Benin historical moats. The region has been described as a tilled plain in the south western direction. The local relief of the region is 91 m. Boreholes records in the Benin Region show evidence of deep chemical weathering overtime. Soil profile reveals that the region is composed mainly of reddish brown sandy laterite. Intermittent layers of porous sands of sandy clays may reach a large depth as found in the borehole drilled in the region. These are products of deep chemical decay of the original parent rock materials. Three river systems drain the Benin Region. They are the Ikpoba River, the Ogba River and Owigie-Ogbovben River systems. The mean annual discharge of Ikpoba River for 1982-1983 and 1993-2002 was 1411 mm/yr, which was 1.019 × 10 9 m 3 with a mean annual baseflow of 1256.23 mm (0. 907 × 109 m 3). This constitutes 87.65% of the total flow. It has a mean annual surface runoff of 225.18 mm (0.112 × 10 9 m 3) or 24.4 % of the total discharge. The water resources of the region include surface water and underground water.

Impact of Urbanizing Ovia-North East on the Quality of Groundwater using Water Quality Index

“…The Local Government Area (Ovia North East) is situated in Benin City and Benin City is located within the rainforest zone of Nigeria with mean annual rainfall in the range of 1500 mm to 2500 mm and the mean monthly temperature varying from 25°C to 28°C (http://www.edoworld.net/Edotourismweather.html). The Benin Region is underlain by sedimentary formation of the South Sedimentary Basin (Ikhile, 2016) and it constitute part of the Benin formation which is made up of over 90% massive, porous, coarse sand with thick clay/shale interbeds having high groundwater retention capacity (Adegbite et al, 2018). The geology is generally marked by top reddish earth, composed of ferruginized or literalized clay sand (Ikhile, 2016).…”

Determinants of Flooding and Strategies for Mitigation: Two-Year Case Study of Benin City

“…Variations in Akoko Edo consist of shallow, stony, reddish clay at the feet of inselbergs in the higher section, lateritic clay and fine-grained to sandy soils, while in the upper slope, lateritic tablelands and ferruginous soil on the crystalline acid rocks are on the basement complex. In Orle Valley, the soil is lateritic, gravelly sand, while on the Esan Plateau, the soil is either clayey sand or porous red sand soil type in the Benin lowland-these soils range from loose, poorly productive sand in the southwest to fertile, clayey soil in the northeast close to the Niger, the Osse, and the Benin River that are alluvial and hydromorphic [18]. As a result, the pedological complexity of the area's soil genesis constitutes factual basis for flood concern via its pedogenic processes and soil patterns.…”

“…Rivers Osse, Orhionmwon, and Ikpoba drain the area. With the exception of the River Osse that has a wide flood plain, the other rivers are characterized by steeply incised valleys in their upper courses; they become broad as they enter River Ethiope in Delta State [17,18]. The Northern Plateau ranges from 183 to 305 m of basement rock with occasional granite peaks rising above 610 m. Its southern portion is mainly sandstone.…”

Physiological and biochemical responses of selected cowpea (Vigna unguiculata (L.) Walp.) accessions to iron toxicity

“…The conditions needed for the cultivation of cowpea such as above 80 % sandy content are also present in some other states such as Edo State, Nigeria, Edo State but have recorded very low production (IITA, 2003). One of the reasons for this shortfall may be due to the presence of high iron in most of these soils (ferruginous ultisols) as shown by the geological evidence of Ikhile (2016) and collaborated by Imasuen & Onyeobi (2013).…”