Aquifer types and the geoelectric/hydrogeologic characteristics of part of the central basement terrain of Nigeria (Niger State)

ion from springs nowadays is through two spring boxes: the protection box to protect the water against surface contamination and the collection box to provide storage and ensure that the all the water from the spring is collected. Loose stones are piled up at the back of the spring box to serve as a wall and to prevent the washing away of soil. the spring boxes are often fitted with an overflow pipe and a drain pipe. From the collection chamber water is conveyed either straight to the consumers or to the service reservoir. Most of the spring capping works done in ethiopia are for small rural towns and villages and are executed at the regional level and often by NGOs working in the area. In ethiopia, wells with depth up to 60 m are normally considered as shallow. Shallow depth wells are either hand dug or augers are employed to drill or are bored using rigs. Most hand-dug wells are lined using either stone masonry or pre-cast concrete rings and when used communally it is normally covered and equipped with hand pumps. the abay river basin master plan estimates that 70 percent of the rural community of the basin gets their water GROUNDWATER AVAILABILITY AND USE IN SUB-SAHARAN AFRICA: A Review of 15 Countries 35 from hand-dug wells fitted with hand pumps and 20 percent from boreholes with submersible pumps. In rural areas where traditional dug wells are used the main water lifting equipment is the ‘‘rope and bucket’’ system. these types of wells are not well covered and mostly exposed to pollution. In wells constructed by the government and NGOs, the hand-dug wells are properly covered and fitted with hand pumps. the walls of the wells are cased with concrete rings or masonry. For shallower wells (up to a depth of 45m), mostly afridev hand pumps are fitted. For depths up to 80 m, Indian Mark II pumps are installed. these hand pumps are selected because of their simplicity during operation and maintenance. they are usually termed as ‘‘Village Level Maintained and Operated’’ (VLMO) pumps. In most places where the groundwater table is at an average depth of 10 m, privately owned hand dug wells are found. these wells are normally open and are rarely lined and may serve as a sole source of water or a supplementary source to the household. Cost of groundwater development the cost of drilling in ethiopia is very high, owing to limited drilling companies and the high price of machinery and accessories for drilling. hence development of groundwater sector requires a huge financial investment towards appropriate machinery and building capacities to handle them. In some governmental organizations like the amhara Water Works Construction enterprise (aWWCe), the cost of drilling is higher, mainly due to the greater staff numbers and the aged machineries with high maintenance cost. Cost analysis of wells shows that the percentage share of cost based on itemized costs varies from place to place and significantly from country to country. In ethiopia all drilling equipment, including vehicles, casings, fuel, oil, lubricant spare parts, etc., are imported, with the depreciation costs accounting for 33 to 42 percent, and the material costs including fuel, oil, grease accounting for 22 to 25 percent and the labour, overhead, profit margin, and Vat accounts for 33 to 45 percent (aWWCe, 2004).typical costs of groundwater development are shown in table 3.5.

https://www.iwmi.cgiar.org/Publications/Books/PDF/groundwater_availability_and_use_in_sub-saharan_africa_a_review_of_15_countries.pdf

Groundwater availability and use in Sub-Saharan Africa: a review of 15 countries

Assessing the impacts of climate change in cities and their adaptive capacity: Towards transformative approaches to climate change adaptation and poverty reduction in urban areas in a set of developing countries

The present work is a review on the quality characteristics of groundwater in Nigeria. The aim was to collate, synthesize and analyse hydrochemical data from available literature in order to evaluate the physical and chemical character, quality and determine the sources of ions. The review process covered four major groundwater sedimentary basins viz Benin, Benue, Niger Delta, Sokoto and the Crystalline Basement Complexes. The issue of saline groundwater in parts of Benue and Niger Delta Basins were given attention. In general, data show that on the average, TDS for the groundwater from the different basins was < 250 mg/l compared to the saline groundwater with average TDS as high as 15700 mg/l. The high salinity was attributed to dissolution of salts and seawater intrusion. Nitrate concentration on the average is high especially, for Sokoto Basin indicating anthropogenic pollution. Descriptive and multivariate statistics together with cross plots indicate that the major geologic controls on the groundwater chemistry are chloride dissolution, weathering (silicate and carbonate) and ion exchange. With respect to agricultural and irrigation purposes, the groundwater are excellent besides the water from the saline groundwater from Benue Basin and the coastal aquifers.

	 

	Key words: Groundwater, chemistry, quality, Nigeri

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Groundwater chemistry and quality of Nigeria: A status review

Lessons learned from Khartoum flash flood impacts: An integrated assessment.

Determining when and where flood strikes can be a daunting task. Apart from heavy and prolonged rainfalls and river overflows, there are anthropogenic causal factors of flooding. These anthropogenic factors are significantly variable and exacerbate floods, but may be difficult to measure. This study aims to unravel some of the anthropogenic factors, particularly with respect to their contributions to the flood in Ibadan City on 26 August 2011. Data were collected through structured questionnaire and key informant interviews. The August 2011 Ibadan flood was perhaps the worst in the history of this ancient city. Twelve anthropogenic factors are broadly identified as having contributed to the flood and the flood had five major consequences. Some policy implications that can help prevent future flood occurrence are outlined.

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The August 2011 Flood in Ibadan, Nigeria: Anthropogenic Causes and Consequences

Groundwater prospects in the basement complex rocks of southwestern Nigeria

This paper revisits flooding problems in Ibadan Metropolis, in the past fifty years, especially the most recent flood of August 2011. Flood disasters can be attributed to the unnecessary risks people take when they encroach on flood plains. There will be no flood disasters if human beings stayed away from the flood plains. The methodology adopted for the flood investigations includes site visits, interviews of affected inhabitants, and analyses of flood data collected during the field investigations. These investigations were complemented with review of past records of flooding, and interpretation of satellite imagery of flood affected areas, especially for inaccessible areas, to produce flood hazard maps. Results of the spatial analysis of flooding in the 11 local government areas of Ibadan indicate that 26,553 buildings were constructed within the statutory set back to the rivers and streams while 2,105 were flooded. Large scale encroachment into the river floodplains was observed throughout the area.  The major cause of flooding in Ibadan Metropolis is due to uncontrolled urbanization of the area. The Nigerian Meteorological Agency (NIMET) predicted that there will be very heavy rains and flooding in a number of states in Nigeria in 2012. In Oyo State, Ibadan is specifically mentioned as a city to experience flooding. This emphasises the urgent need to put in place measures to facilitate effective management of the anticipated floods to prevent the re-occurrence of the damage and losses of the 2011 disaster.

Flood Management in an Urban Setting: A Case Study of Ibadan Metropolis

Quality of groundwater in the Coastal Plain Sands aquifer of the Akwa Ibom State, Nigeria

Boreholes drilled in the crystalline rocks of Nigeria have a reputation of failures and low yields. The performance of 256 boreholes drilled in different parts of the crystalline rocks of SW Nigeria were reviewed to determine their failure characteristics. 100% success was claimed for 105 boreholes constructed by one driller. Out of 111 other borehole records supplied by three other drillers 35 were abortive, representing a failure rate of 32%. In contrast, 24 owners of 40 boreholes reported 24 failures representing a failure rate of 60%. The common causes of borehole failure in the crystalline rocks of SW Nigeria are seasonal variations in water level, improper casing of the overburden, damage to pumps and other system failures such as blocked pipelines and malfunctioning tanks. Non-penetration into the water bearing horizon also features as a cause of borehole failure in this study. It is suggested that proper construction, operation and maintenance of boreholes will reduce the incidence of borehole failures in crystalline rocks of SW Nigeria.

Owolabi Ajayi

Papers

The August 2011 Flood in Ibadan, Nigeria: Anthropogenic Causes and Consequences

Groundwater prospects in the basement complex rocks of southwestern Nigeria

Flood Management in an Urban Setting: A Case Study of Ibadan Metropolis

Quality of groundwater in the Coastal Plain Sands aquifer of the Akwa Ibom State, Nigeria

Borehole failures in crystalline rocks of South-Western Nigeria