ABSTRACT
A study on the geology and hydrogeology of part of Minna Sheet 164NE was conducted with the aim of establishing the groundwater potential and control mechanism. Minna lies along longitude 6°30′E and 6°32′E and latitude 9°37′36′′ N and 9°39′34.5′′ N covering a total area of 14 km2. The area has a high population most of whom depends on groundwater for domestic uses. Geology of the area was studied on a scale of 112,000 using traverse method. Structural disposition of outcrops was established and positions taken. Thin sections of representative rock samples were made and analysed using petrological microscope. Groundwater inventory consisting of well locations, including borehole depth, water level and yield were taken. Samples of the water were obtained and analysed for physical and chemical composition. 90% of the area is underlain by rocks belonging to the older granite suite of the Nigerian Basement complex system while the remaining 10% is underlain by schist. Joint direction is principally in the NNE-SSW. Thickness of the weathered rock is in the range of 5-10m. Wells have a mean depth of 5m and water level of 3.57m. Boreholes have an average depth of 134m and mean yield of 71.28m3/d(0.83lt/s). Groundwater potential map shows that the north-eastern part of the area has greater potential at shallow level while other areas have slightly lower potential. Regional groundwater flow is in the NE-SW direction. Groundwater has a mean pH of 7.3, Electrical Conductivity 637.5µS/cm, and temperature of 28.6oC. Parameters with higher concentration include chloride 82.35mg/l, bicarbonate 70.18mg/l, sodium 56.18mg/l and calcium 46.16mg/l, nitrate. Trace elements that occur in fairly high concentration include zinc 1.15mg/l, phosphate 0.81mg/l and fluoride 0.32mg/l. The water primarily plots as mixed calcium- magnesium-chloride water and secondarily as sodium-bicarbonate water. The heavy metals are considered as Potentially Toxic Elements (PTEs)
CHAPTER ONE
1.0 INTRODUCTION
1.1 Background to the study
According to The Department of Economic and Social Affairs (Vale, 2017), half of the global population already lives in cities, and by 2050 two-thirds of the world’s people are expected to live in urban areas. But in cities two of the most pressing problems facing the world today also come together: poverty and environmental degradation. The majority of people move to cities and towns because they view rural areas as places with hardship and backward/primitive lifestyle. Therefore, as populations move to more developed areas (towns and cities) the immediate outcome is urbanization. This normally contributes to the development of land for use in commercial properties; social and economic support institutions, transportation, and residential buildings. Eventually, these activities raise several urbanisation issues.
Poor air and water quality, insufficient water availability, waste-disposal problems, and on density and demands of urban environments. Strong city planning will be essential in managing these and other difficulties as the world’s urban areas swell. Urban populations interact with their environment. Urban people change their environment through their consumption of food, energy, water, and land. And in turn, the polluted urban environment affects the health and quality of life of the urban population.
Approximately 97% of the earth’s water is stored in the oceans, and only a fraction of the remaining portion is usable freshwater. When precipitation falls over the land, it follows various routes. Some of it evaporates, returning to the atmosphere, some seeps into the ground, and the remainder becomes surface water, traveling to oceans and lakes by way of rivers and streams.
Impervious surfaces associated with urbanization alter the natural amount of water that takes each route. The consequences of this change are a decrease in the volume of water that percolates into the ground; and a resulting increase in volume and decrease in quality of surface water. These hydrological changes have significant implications for the quantity of fresh; clean water that is available for use by humans, fish and wildlife.
Air pollution often plagues industrialized cities, particularly during their early development. Episodes of high levels of sulphurous smog killed or sickened thousands in Donora in 1948, as well as in London in 1952. Other cities—primarily in the industrialized regions of the United States and Europe—also suffered from notoriously bad air quality. These events were the result of very high emissions of sulphur dioxide, smoke, and other particles during stagnant, foggy weather conditions.
Urbanization has led to reduced physical activity and unhealthy nutrition. The World Health Organization predicts that by 2020, non-communicable diseases such as heart disease will account for 69 percent of all deaths in developing countries. Another urbanization-related threat is infectious diseases. Air travel carries bacteria and viruses from one country to the next. In addition, people relocating from rural areas are not immune to the same diseases as long-time city residents, which puts them at a greater risk of contracting a disease.
The cost of living in urban areas is very high. When this is combined with random and unexpected growth as well as unemployment, there is the spread of unlawful resident settlements represented by slums and squatters. The growth of slums and squatters in urban areas is even further exacerbated by fast-paced industrialization, lack of developed land for housing, large influx of rural immigrants to the cities in search of better life, and the elevated prices of land beyond the reach of the urban poor.
Although urbanization is a necessary condition for modernization, we can mitigate the effect of it. We just need to learn how to save the planet and conserve our natural resources, through recycling water and the use of renewable energy.
Water is essential for the survival of every form of life and the need for water is constantly increasing due to high rates of population growth and urbanization. However, the increased demands in water for drinking, domestic agricultural and industrial purposes are not commensurate with water availability thus, posing significant risks in maintaining acceptable water quality. Therefore, the quality of accessible water is an important index of the living standard (Dara, 2000; Gopinath et al., 2011). Hydrogeochemical study of water sources involves the studying of the chemistry /geochemical elements of water, nature and quality of water in relation to its geology and waste disposal. Mineralogical composition of the underlying rocks and the nature of the surface run off are factors that affect quality of groundwater. Hence, the quality of groundwater is largely controlled by a discharge and recharge pattern, nature of host and associate rocks as well as human activities.
In the study area, there is the challenge of lack of supply of pipe borne water hence many homes have wells sited around the house at unacceptable distances from the septic tanks. It is known that for most communities, the most secure source of safe drinking water is pipe-borne water from municipal water treatment plants. Often, these water treatment facilities do not deliver or fail to meet the water requirements of the served community due mostly to increased population. The scarcity of piped water has made communities to find alternative sources of water where ground water sources are a ready source. Well is a common ground water source that is explored to meet community water requirement or make up the short fall.
These wells serve as major source of water for household uses (drinking, cooking, washing etc.). The most common cause of pollution is attributed to close proximity of septic tanks to wells, unhygienic usage of the wells for example some wells have no cover/lids; they are dirty and unkempt thus, making the water unfit for use, resulting into water borne diseases.
1.2 Statement of the research problem
Ethically, the beauty of any environment lies on its good sanitary condition. This is so because, when an environment is clean the lives of citizenry are not threatened by illnesses and diseases. Proper solid waste disposal is necessary to maintain this status. Also, proper use of available resources is required to ensure sustainability of these resources. Poor environmental management practices and unsustainable demand for natural resources have due to urbanization led to inadequacy in water supply, poor sanitation and environmental degradation issues. This research therefore, seeks to unravel ways in which groundwater has been impacted and recommend ways in which this situation can be remedied.
1.2.1 Some characteristics of the study area
The characteristics of the study area include:
• Densely populated (overcrowded).
• Houses closely packed together and built indiscriminately.
• Poor drainage system.
• Poor sanitation facilities.
• No proper planning.
• Waste disposal system is mostly in open dumps and drainages.
• Inhabitants rely heavily on groundwater for water supplies.
1.3 Justification for the study
It has long been recognised that urbanisation results in important changes to the groundwater balance both by replacing and modifying groundwater mechanisms and by introducing new discharge patterns due to abstraction from wells. In particular, main water and sanitation systems can have a significant impact on shallow aquifers that underlie a city and they may become major components of the urban hydrologic cycle as a result of leakage and/or seepage. The aquifers at such depths have been overwhelmed by population growth and other environmental conditions. Also, aquifers beneath these sites are also prone to contamination.
Further pressure is anticipated as the years go by considering the fact that Minna is experiencing a high population growth rate. Therefore, investigating these activities which are a direct result of urbanisation is important. Furthermore, the results of these investigations will provide information that would be utilised by agencies of the government and public sector to make policies that would regulate these activities. UNEP and WHO (1996), argued that it is not significant to merely have access to water in adequate quantities. The water also needs to be of adequate quality to maintain health and it must be potable. Poor sanitation or lack of them, improper municipal and industrial waste disposal system could pose pollution problems to groundwater supplies. For example, influent seepage of urine and leachate from polluted surroundings, a pit latrine or a soak away, sited upstream and near a borehole, could enrich the groundwater with phosphates and ammonia (Okoye and Adeleke, 1991).
1.4 Scope of work and limitations
This research seeks to establish impacts of urbanisation on the environment as it relates to groundwater contamination in shallow aquifers as well as the effects regarding to open dumpsites using information on open dumpsites, hydrogeological and hydrogeochemical data.
The study was limited to Kpakungu, Soje and Barikin Sale areas. It involves a study of the geology, hydrogeological conditions, water quality, wastewater and solid waste disposal as they relate to groundwater contamination. The various results will be used to propose strategies for effective use and sustainability of groundwater resources and suitable methods of solid waste disposal. Acquisition of archived secondary data from relevant agencies may be problematic due to challenges in archiving data by these agencies. However, these limitations will have no negative impact on the outcome of the research.
1.5 Aim and objectives of the study
The research is aimed at evaluating the impact of urbanisation on water resources in parts of Minna metropolis, North Central Nigeria.
Objectives of the study are to:
i. Determine the geology, hydrogeology and the weathering profile of the study area.
ii. Determine the extent of pollution of water due to developmental activities.
iii. Determine the quantities and types of waste generated in the study area
iv. Assess the impacts of activities on the groundwater system and the environment of the study area.
1.6 Study area description
1.6.1 Location, Extent and Accessibility
Minna, the capital city of Niger State is located within the North-Central part of Nigeria. It is located between Latitudes 9°35ˊ24˝N and 9°38ˊ24˝N and Longitudes 6°31ˊ12˝E and 6°34ˊ12˝N. It covers Chanchaga Local Government Area and parts of Bosso Local Government Area.
The focus of the study covers Kpakungu, Barikin-Sale and Soje areas of Minna.
1.6.2 Climate and Vegetation
The area falls within the Guinea Savannah vegetation. There are two seasons associated with the climate. These include the rainy and dry seasons. The total annual rainfall in this area is between 1270 mm and 1524 mm, spread over the month of April to October (NIMET, 2019). The maximum daytime temperature is about 35°C in the months of March and April, while a minimum temperature of about 24°C is recorded in the months of December and January. The mean annual temperatures are between 32°C to 33°C. It should however be noted that the above climatic conditions stated are subject to changes. The dry season is marked by influence of harmattan which is a result of North- East trade wind that blows across the Sahara and that is often laden with red dust and lasts from the month of December to the month of February.
1.6.3 Relief and drainage
The area is majorly flat line with contour values ranging from 350 – 400 m also found within the area occurring as a spot height is the geographical point reference referred to as the Minna datum which defines the Universal Traverse Mercator (UTM). This is an elevated spot in the predominant part of the area studied at the top of which the Niger State water and sanitation board placed a 10 million litre capacity concrete reservoir for water distribution by gravity flow to neighbouring areas.
The drainage pattern of the area is the dendritic pattern, seasonal rivers such as river Biyako, Dutsen Kura and Gbaiko drain the area with smaller tributaries joining them. This all eventually drains into River Chanchaga which is a perennial river that occurs in the southern part of the sheet flowing in the SW direction. The seasonal stream within the study area flows from the NE-SW direction. Figure 1.3 is the topographic map of parts of Minna covering the study area, it shows the topographic structure and drainage of the study area.
1.6.4 Local Geology
Minna falls within the North-Central part of Nigeria; the study area is Basement Complex of Nigeria is underlain by Precambrian rocks. This groups of crystalline rocks generally represents; Migmatites, Gneisses, and Meta-Sedimentary Schist (Adeleye, 1976). Two lithological units underlie the area; granites and Gneisses with Pegmatites and quartz veins. About 80% of granitic rock is covered in the areas which are exposed mainly at the western part of the town. The highly jointed, fractured, foliated outcrops are granitic which appears as boulders in some places. The second lithologic unit which is gneiss covers about 20% of the total area. (Adeniyi, 1985). Gneissose banding which
are fine grained, characterized by swaying lighter coloured minerals of quartz and feldspar, darker coloured biotite-mica with an intrusion of highly weathered and fractured granitic rocks. A few of the Gneisses contain augen structures, banding and boudinages.
This material content is developed to serve as a GUIDE for students to conduct academic research
ENVIRONMENTAL EFFECTS OF URBANISATION ON GROUNDWATER RESOURCES IN PARTS OF MINNA METROPOLIS, NORTH-CENTRAL NIGERIA
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