IMPACT OF LAND USE CHANGE ON ATMOSPHERIC TEMPERATURE VARIATIONS IN PORT HARCOURT METROPOLIS
IMPACT OF LAND USE CHANGE ON ATMOSPHERIC TEMPERATURE
VARIATIONS IN PORT HARCOURT METROPOLIS
NALUBA BARINEKA AMBROSE
BEING A RESEARCH PROJECT SUBMITTED TO DEPARTMENT OF GEOGRAPHY AND ENVIRONMENTAL MANAGEMENT, FACULTY OF SOCIAL SCIENCES, UNIVERSITY OF PORT HARCOURT, IN PARTIAL FULFILLMENT OF THE REQUIREMENT FOR THE AWARD OF BACHELOR OF SCIENCE (B.SC) DEGREE IN GEOGRAPHY AND ENVIRONMENTAL MANAGEMENT
This study is primarily concerned with the impact of land use change on atmospheric temperature variation in Port Harcourt metropolis. It looked at the average temperature of the metropolis, and the temperature at various land – use surfaces. In addition to that, 303 questionnaires were administered from which 298 were analysed; also data was collected from the Nigeria meteorological agency. These data were subjected to statistical analysis and it was observed that statistical relationship exist between land-use type and atmospheric temperature variation, it was also discovered among others that there is no statistically significant difference between the temperature of Port Harcourt metropolis and that of its surrounding rural area. To this end the study recommended that urgent steps should be taken to control the rate and manner in which structures are erected within the city and to ensure that effort of the government to plant trees along major roads of the metropolis should be taken to other parts, and laws should be put in place to protect natural surfaces.
- BACKGROUND TO THE STUDY
The City of Port Harcourt had a humble beginning in 1913 as a fishing settlement, with initial population of about 5,000 people, Oyegun (1999). The city was cited on firm ground, 66 kms from the Atlantic Ocean, by the colonial administration to facilitate the inflow of goods and services in the region.
At its inception, the new city extended from the UTC junction to the new layout market. Nwala et al (1979) asserts that Diobu and Borikiri became part of the city in 1969, they further stated that consequent on the rapid industrial and commercial growth of the city in the 1960’s Port Harcourt expanded to include Ogbunabali, (East and West). Obio I and II and Oroworukwo. Port Harcourt city and Obio/Akpor Local Government and Council had their northern limit stretching from Choba to Rukpokwu and Eastwards to iriebe following the Local Government reforms of 1967.
Okoye; (1975) documents the population dynamics of the city as 7,185 in 1921, 15,201 in 1931 and 71,635 in 1953, the census of 1963 recorded that Port Harcourt has a population of 179,563. While Ogionwo; (1979) puts the population of the city in 1973 at 213, 443 and in 1991, the National Population Commission recorded the population of the city as 643,885 persons. Between 1991 and 2006 when the next national head court was conducted the city had more than double in population with Port Harcourt city, Obio/Akpor, Eleme and Oyigbo L.G.A’s, recording a total population of 1, 319, 474 persons.
This is an indication that the city is urbanizing at a very rapid rate. The land use and vegetation map of the Area drawn in 1975 shows that built up area of the city and its environment was only 16.25km2, but by 1995 an updated edition shows an increase to 285.25km2, indicating an increase of 17% in 20 years Oyegun (1999). This position has of course tripled by the year 2008.
The implication of this is that most of the vegetation has been converted to various industrial public and semi-public, transport, communication and recreational land uses. This modification of the vegetation can have dare consequences on the micro-climate of the metropolis.
- STATEMENT OF THE PROBLEM
Change in atmospheric temperature is not new to earth; Miller (2004) agrees that the past 900,000 years of the 4.7 billion years of earth’s history have witnessed prolonged periods of global cooling and warming. Thick layers of glacial ice covered vast areas of earth surface for about 100,000 years, these glacial periods alternate with warmer inter-glacial periods which last for between 10,000 and 12,500 years with marked increase in the temperature of the atmospheric.
The implication of the above statement is that variations in atmospheric temperature have been an inter-glacial part of earth’s history and that long term global temperature change is beyond man. Changes are inevitable and in most cases beyond man’s control. On the other hand we must seek to understand and manage short term variations in atmospheric temperature, which occur within the life span of present generations. Christopherson (2002) has observed that the last two decades were dominated by record high global atmospheric temperatures for both land and ocean and for both day and night with 1998 recording the highest temperature since the past 420,000 years.
Scholars are unanimous on the view that these noticeable increase in atmospheric temperature are as a result of human activities that have altered the natural land scape, and increased the amount of greenhouse gases within the lower atmospheric. Table 1.1 below an increase in the atmospheric concentration of Co2 for the periods between 1774 and 2050.
|Year||C02 Concentration||Parts per million (PPM)|
Source: christopherson (2002) adopted from Oyegun (2007)
Imyunka (2009) submits that the greatest culprit of global atmospheric temperature variations is the city, considering the fact that weather stations are situated around cities and the growth of cities can be directly linked with temperature increases.
This view is quite interesting, considering the fact that cities are growth centres and as human populations increase they tend to modify a greater area of land which has a corresponding increase in atmospheric temperature. The buildings, concrete, asphalt and industrial activities of urban centres tend to cause cities to maintain higher temperature than there surrounding country side.
Table 1.2 below shows modification in climate induced by urbanization and industrialization.
|Element Dust Particles||Compares’ with sub-urban Area 10 times more|
|Sulphur dioxide||5 times more|
|Carbon dioxide (C02)||10 times more|
|Carbon monoxide (C02)||25 times more|
|Radiation||5 to 20times more|
|Cloud cover||5 to 10% more|
|Sunshine duration||5 to 10% less|
|FUME||30 to 100% more|
|Precipitation||5 to 10% more|
|Temperature||0.3 to 1.0C0 more|
Source: Landsberg (1970)
Residents of Port Harcourt could observe that in recent past, there has been noticeable increase in the level of discomfort around the metropolis, especially in the evenings and this when compared to the report of the Nigeria Meteorological Agency which confirms that the night time temperatures over Port Harcourt have increase by 0.5 – 3.40C. These have led the researcher to ask the following questions.
- RESEARCHER QUESTIONS
During the study we attempted to answer the following questions.
- Is there a difference in the atmospheric temperature at different land uses within the metropolis?
- Is there any relationship between temperature and the level of discomfort, at the various land use surfaces?
- Is there any relationship between land-use type and the prevalence of temperature related sickness in the city?
- Is there any difference between the temperature of Port Harcourt metropolis and that of the neighbouring rural areas?
- AIMS AND OBJECTIVE
The aim of study is to examine the impact of land-use change on atmospheric temperature variations in Port Harcourt metropolis to achieve this aim, the following specific objectives where pursued.
- To examine the spatial variation in atmospheric temperature at different land-uses in Port Harcourt metropolis.
- To identify the relationship between temperature and level of discomfort in different land-use types in Port Harcourt metropolis.
- To ascertain if there is a relationship between land use type and the prevalence of temperature related ailments in the city.
To identify the urban – rural difference in temperature in the study area.
- RESEARCH HYPOTHESES
- Null Hypothesis I Hoi
There is no significant relationship between land use type and atmospheric temperature in Port Harcourt metropolis.
- Null hypothesis II Hoii
There is no significant difference between the temperature of Port Harcourt metropolis and that of its surrounding rural areas.
- SCOPE AND LIMITATION OF THE STUDY
The study was designed to examine the impact of urban land uses on temperature variations in Port Harcourt metropolis. Which also included the average temperature over time? In the cause of the study, we looked at the perception of people about the temperature of the city and if it has any impact on them. The study also looks at the degree of impact at various land uses.
However we had some limitation which included the reluctance of related government agencies to release data, and the non-availability of equipment that would have aided the research.
The contribution of other climatic factors on the problem, so as to fully understand how land use affects temperature.
The study covers 4 local Government Areas that makes up Port Harcourt metropolis, these are Port Harcourt city Local government area, Obio/akpor Local Government Area, Eleme local government area and Oyibo Local Government area. The Ikwerre Local government Area was used as a control to check the difference in temperature between the urban and rural settlements.
The major limitations of the study, was the time factor, because the time allocated for the research was not enough to collect enough data although secondary data was collected from, research agencies in other to make up for the time.
- GEOGRAPHY OF THE STUDY AREA
LOCATION: The study area is Port Harcourt metropolis. It is the hub of industrial and commercial activities in Rivers State. The area lies between longitude 40 48” and 50 00” N and latitude 60 rr” and 70 10”E.
Climate: climatically, due to its proximity to the equation. Its climate is tropically hot (humid). The mean annual temperature of the area is 300c. It is predominantly under the influence of the monsoon wind and also record heavy rainfall of 2370.5mm because of its elevation and urban factors especially pollution from industries,(osuiwu and ologunorisa, 1999). The rainy season which begins around April lasts through November with double maxima characteristics, that is, highest rainfall within June/July and September/ October with little break (August break). Similarly, the area experiences about five mouths of dry season which starts from about November through March.
Also climate system particularly rainfall in Nigeria is primarily the result of the interplay between two major pressure and wind systems.
It is the dynamically generated sub-tropical high pressure cells centred over Azores Archipelago (off the west coast of North Africa) and St. Helena Islands (off the coast of Namibia). These high pressure centres (or anticyclones) which are permanent, generate and drive the North East trade winds and the South-east winds which are northward extension of the South-east trade winds of the South Atlantic Ocean. Both air streams blow over the area at various seasons of the year. It is important to note that these air streams follow apparent movement of the sun, which passes the region twice on its ways to and from tropic of cancer.
The Port Harcourt metropolitan fringe area is endowed with abundant sunshine by virtue of its geographical location near the equator hence, the sun is vertically overhead throughout the year. Daylight hours are longer, because of the long duration of solar radiation at the surface which is substantially reduced mainly due to cloudiness consequent upon its coastal location. These moderating influences induce slight diurnal, monthly and annual variation in temperature over the region. Other influences aside cloud cover; include the harmattan, and the influences of vegetation.
Soils: the soil of the area consist of various types of superficial deposits overlying thick tertiary sandy and clayey deposits which are over 100m thick in places. The consistently high rainfall and temperature of the area encourage intense chemical weathering of the rocks, which result in the formation of clay minerals that are ubiquitous in the area.
Two broad groups of soils can be identified in the area. These soils are derived from the older sediments and those formed on younger quaternary and recent alluvium. The older soils have textures dominated by coarse sandy clays and loose reddish brown sandy loan topsoil. The younger soils have textures which, vary from sand to clay minerals that are ubiquitous in the area.
Two broad groups of soils can be identified in the area. These soils are derived from the older sediments and those formed on younger quaternary and recent alluvium. The older soils have textures dominated by coarse sandy clays and loose reddish brown sandy loan topsoil. The younger soils have textures which, vary from sand to clay but are mainly loamy.
The soils are generally poorly drained but have rich humus layers on the topsoil. Nitrogen and potassium are the most deficient minerals in the soils of the area because of intense leaching due to the rainfall. Volcanic parent materials, which derive from the Ogba highlands, make the soil of the area rich in phosphorus.
Relief and drained: The relief of a place describes the high and low land, when these high and low surfaces are considered over a large area or a place then the entire surface is referred to as the topography of the area or region.
Drainage on the other hand, describes the rivers and water-bodies that are present at a particular location.
The presence of numerous creeks, water bodies and rivers as well as extensive swamps is noticeable in the area. The relief of the area is low lying and the rivers are influenced by tidal fluctuations. In terms of general surface features, the area is very unique. The area falls within the coastal belt dominated by low-lying coastal planes which structurally belongs to the sedimentary formations of the recent Port Harcourt in Niger Delta (Umeuduji and Asuebogun 1999).
Izeogu and Aisuebegun (1989) view the beach ridge barrier Islands as depositional landforms which receives fine to coarse grained sands from the sea.
Generally, the land surface slopes gently (30 – 50 on the average) in a NW-SE direction.
The northern quadrant of the area characterized by gently rolling plains while swamp tidal basins, mud flats and sandbank predominate in the Southern sections of the area or region. One of the most striking features of the area or region is the uniqueness of surface drainage. Areole (1983 as cited by Umeuduji and Aisuebegun, 1999) describes the drainage of the area as poor, essentially due to a combination of low relief, high water table and high rainfall. The low relief of the area or region results in strikingly gentles slopes which have the effect of making flow velocities of the rivers very low. This situation results in the formation of well-developed river meanders. According to Aisuebegun (1995), meandering rivers in the area or region are irregular or even tortuous with sinuosity values exceeding 1-9.
The area falls within the Saltwater/Freshwater Transition Zone. The Imo Rivers just north of the area feeds several creeks, which ultimately merge with the Okrika/Bonny River and the New Calabar River. In the development of the area, some attempts have been made to integrate the natural drainage system with the built drainage system. The problem of flooding in the area and periodic urban flooding is worsened by the blockage of these drainage systems with refuse or even unplanned and illegal housing development, (Alagoa, 2002).
A closer observation of the rivers and Creeks and bodies in the area and its environs shows that the Network pattern created does not easily fit the conventional, typical dendrite or trellised pattern of drainage.
The entire area is crises-crossed by several rivers and creeks even water bodies which empty, into the Atlantic Ocean.
Transportation: Transportation is an essential service which enable the people, firms and various others to interact at spatially dispersed locations or centres. Interaction between the metropolitan fringes and city centre is made possible through linkages on the form of transport networks. The transport system in the area is the area is therefore a vital medium through which the interdependence of then complex, urban activities gets satisfied. It is also a medium through which integration is accompanied.
Once links are established the traffic flow in the area will be generated and will also be attracted from other areas; this however, depends on the complimentarily and transferability’s between the two areas, and the existence of intervening variables.
CONCEPTIONAL FRAMEWORK/LITERATURE REVIEW
Around half of the world human population live in urban areas (Arm field 2003). In the near future it is expected that global rates of urbanization will increase by 70% of the present world urban population as urban agglomeration emerge and population migration from urban to rural/sub-urban areas increase (Bailey et al 1997 voogt 2002). Therefore, it is not surprising that the negative impacts related to urbanization are an increasing concern capturing the attention of people worldwide.
In this chapter our primary task is to highlight various findings that have been published about the relationship between the growth of urban centres and the increase of its temperature in other to do this, the researcher uses two main headings which are the theoretical framework and the literature review.
2.1 THEORETICAL FRAMEWORK
GLOBAL RADIATION BALANCE
The difference between the amount of energy that enters and leaves the atmospheric is referred to as the earth’s heat balance (Kaufman and clover land 2008). Researchers are of the view that since earth is neither warming up nor cooling down (under normal conditions), there must be a balance between incoming isolation and outgoing terrestrial radiation. (Waugh 1995) reports that-
- There is a net gain in radiation everywhere on the surface of the earth except in Polar Regions which have high albedo surfaces.
- There is a net loss in radiation throughout the atmosphere
- After balancing the incoming and outgoing radiation there is a net surplus between 350 South and 400 North (this difference in latitude I attributed to the larger land masses of the northern hemisphere) and a net deficit to the pole ward side of these latitudes.
This according to (Waugh Ibid) means that there in a positive heat balance within the tropics and a negative heat balance at high latitude and high altitude. Two major flows or transfers of heat take place to prevent tropical areas from overheating and polar regions from freezing they include:
- HORIZONTAL THAT TRANSFER (FLOW). Heat is transfer away from the tropics, this preventing the equator from becoming increasingly cooler. Wind (air movement including set streams, hurricane and depressions) are ocean current are responsible for 20%
- VERTICAL THAT TRANSFER (FLOW)
Heat is transferred vertically thus preventing the earth surface getting hotter or cooler.
Table 2.1 below shows the radiation balance during every year in kly per year
|The Earth surface||124||52||72|
Source Ayoade (2004).
Source Waugh (1995).
The theory above describes a delicate balance between the incoming and outgoing radiations incidents upon the surface of Earth, it introduces us to different energy flows that help regulate the temperature on earth. Concerning these flows Cleveland and Kaughman (2008) warns that alteration in the flows can have severe consequences on earth and its inhabitants.
It can also be deduced from the framework that settlements within the same region of Earth should have the same temperature, since they receive the same amount of radiation every day. But this has been proved otherwise, as researchers between those of an urban centre and that of its surrounding rural areas. A phenomenon, they describe as the urban Heat Island (UHI).
2.1.1 URBAN HEAT ISLAND
Modern urbanization has a pronounced influence on most components of the energy balance and related atmosphere conditions (Marsh 2001). Generally the larger the city and the denser it’s population and development the greater the magnititude to change. Urbanization, negatively impacts the environment, mainly by the production of pollution, the modification of the physical and chemical properties of the atmosphere, and the covering of the soil surface.
Table 2.2 below is a summary of the energy-balance change in the components of urban climate.
|Incoming short wave radiation||Degrees
|Dust done, green house effect|
|Outgoing long wave radiation||Degrees
|Hard surface, sparse plant cover|
|Sensitive heat||Increase||Hard surface oversoil sparse plant cover|
|Mechanical turbulence (ground)||Degrees
|Large building and other structures|
|Convectional turbulence source Marsh (2001)||Increase||Heat island|
Source Marsh (2001).
Considered to be a cumulative effect of all these impacts is the urban heat island (UHI) it is defined as the rise in temperature of any man made area, resulting in a well-defined, distinct “warm Island” among the “cool sea” represented by the surrounding landscape which has a lower temperature (Kim 2005) Peterson (2003) is of the opinion that though heat islands may form on any rural area, at any spatial scale, cities are favoured since there surface are prone to release large quantities of heat.
In an earlier description of the phenomenon of urban heat island Hartson (1980) stated that higher temperatures are common in central city areas as compared to sub-urban and rural settlements, this he attributed to the presence of taller, darker and the abundance of vertical walls paved streets, and parking areas, which trap radiant energy in an urban environment in the works of Raven et al (1998). Heat released by human activities such as fuel combustion is also highly concentrated in areas of high population density, as a result the air in urban areas are warmer than that of it surrounding rural areas.
According to Waugh (1995). Large cities and combinations experience climate conditions which differ from those of the surrounding country side, they create heat; alter the chemical compositions and moisture content of the air. The main case of urban heat island has been attributed to the modification of land surface by urban development which uses materials which effectively retain heat, waste generated by secondary contributor. Ojo (1982) brings home this concept as he affirmed that Africa cities, have undergone considerable changes in their landscape, which has resulted in the alteration of the heat balance of these cities, increasing their temperature
The urban heat island effect is a way through which research have explained the alteration of the flows that make up the earths-energy balance these alterations have resulted in greater consequences and could even lead to more if measures are not taken.
2.2 LITERATURE REVIEW
Have a looked at a general framework on the topic so far, it is now pertinent for us to look at related literature concerning how the concept so described has affected port Harcourt if possible by looking at literature that could established this fact in port Harcourt.
2.2.1 SPATIAL GROWTH OF PORT HARCOURT METROPOLIS.
The city of Port Harcourt has undergone tremendous changes especially in its spatial formation. Actual policies and decision that lead to the creation and development of Port Harcourt started in 1912 (Port Harcourt master plan 1975) work began on the site of Port Harcourt on 10th November 1913. The city started growing rapidly, thus Anyanwu (1979) observed that the division of the town into two distinct residential areas, Europen and African helped to solve the planning problem of zoning right from the beginning of Port Harcourt history.
As early as 1926, the town was completely laid out and the cities were demarcated for building purposes, separating the two residential areas was a so called neutral zone, a quarter of a mile in breath and extending round the European towns, the green belt was kept clear of any undergrowth, and parade ground Nwala (1979).
Port Harcourt grew rapidly with new trends in both commercial and residential forms between 1925 and 1934, during this period, growth in trade was marked by a rapid expansion of the known beach road now Azikiwe Road, further more in 1928 a market was located at the Western end of what was then an African settlement close to the railway Nwala (Ibid). This market later became the famous Port Harcourt main market which was destroyed during the civil war.
In 1952, layouts and development of Diobu which as of then was located at the sub-urban of the city commercial, in the sixties, the trans amadi industrial estate was established by the eastern Nigerian Government. The Rainbow town Neighbourhood was developed by the Eastern Nigeria Housing corporation during this period to meet the housing need of the industrial estate (Anyanwu 1979).
Increase in political status of the city, lead to an increase in population resulting in a significant increase in the city to include Diobu creek layout, Ogbunabali east and west, Obio/ and 2 layout and the Oroworukwo commercial layout Nwala (0p.cit).
Port Harcourt urban from the master plan of 1975 covered build-up area of approximately 39.06km2, this area included Gborokiri main town, old G.R.A, Rainbow town, TransAmadi, Diobu, Ogbunabali, orogbum shell R.A, Rumukwurushi, Rumuigbo, RSUST and Amadi flat. Dar-al areas like okrika, Eleme Woji, oyigbo, Rumueme, Mgbuoba, Rumuomasi, Rumuigbo, Rumuokwuta, Rumukalagbo he further reports that the actual built up are of port Harcourt in 2008 is approximately 106.77km2. This however excluded water bodies and forest Area. And with the introduction of the greater Port Harcourt, master by the Amaechi Administration, the city, will still steal experience greater growth higher of commercial and industrial activities.
2.2.2 NATURAL SURFACES AND ATMOSPHERIC TEMPERATURE
It is a well-known fact that progressive replacement of natural surfaces by built surfaces, through urbanization constitute the man case of urban Heat island Buaman (2009). Natural surface are often composed of vegetation and moisture-tapping soil Buyantisyav and W.U. (2009). Therefore they utilize large proportions of the absorbed radiation in the evapotranspiration process and release water vapour that contributes to cool the air in their vicinity (BBauman Ibid).
Also vegetation intercept radiation and produce shade Heat also contribute to reduce heat in its area. The radiation of these areas such as parks and forest not only reduce these benefit but also inhibit atmospheric cooling due to horizontal air circulation generated by the temperature gradient between vegetation and urban centres (ka to and Yamaguchi 2005).
Vegetable according Cunningham and Cunningham (2006) also act as a carbon sink, and due to this activity most of the carbon-dioxide that could have altered the temperature of the environment is absorbed but vegetation thereby regulating the temperature. Absence of vegetation from urban centers can deprive the residents of these benefits and lead to the accumulation of heat.
Port Harcourt metropolis is usually a rainforest vegetation, but as a result of urbanization most of it forest have been replaced but building of different heights and colours;
2.2.3 BUILDINGS AND ATMOSPHERIC TEMPERATURE
He narrows arrangement of buildings along the city’s streets from crayons that inhibit the escape of the reflected radiation from most of the dimensional urban surfaces space. This radiation ultimately absorbed by the building walls thus enhancing the urban heat release. The obstruction of rural air flow by the wind ward face to built-up surfaces have been recognized as additional sources of heat. (Stathopoulos et al 2006), Streotkeu 2002, waug et al 2004).
Emenike (1999) reports that Residential areas of Port-Harcourt metropolis comprise of high, middle and low income classes. There are about eight major low and middle income are which include Diobu main town, Borokiri, Dockyard Harbour area, Orogbum layout, Oromenike, Rainbow town. The high income class residential areas are old G.R.A, presidential housing estate. Emenike (Ibid) reports that low income areas are (characterized with tenement buildings, which are compacted with little or no room for ventilation in between houses. These areas are compared by high accompany ratios of up to an occupants within the same room.
High income house in G.R.A for example are mainly Bungalows and Duplexes properly spaced with little occupancy to those of the low income areas.
2.2.4 LINKAGES AND ATMOSPHERIC TEMPERATURE
Asphalt paved roads have thermal and radioactive properties that promote a high heat release Waug et al (2004). As a result of this the total number of paved surface in an urban centre has a significant impact on the temperature of the area. Aghogomeh and Obot (1999) describe the road not work of Port Harcourt Heat as follows.
“The Port-Harcourt metropolis has three major important trunk A roads. Those are the Port-Harcourt Aba express way, the Ikwere Road and the East-West road. The Port Harcourt-Aba Expressway, which runs northwards links directly such hinterland town as Aba…………………………
The Ikwere road on the other hand runs in South north direction and link the city directly with Owerri……………………………. East-west road which is part of the proposed trans-west African route as the name implies, runs in a West-East direction crossing Ikwere road at Rumuokoro junction.
These roads stand out as the back bone or arteries, from which ribs or lines of feeder roads runs off into various directions in the city. The major feeder roads run within the metropolis are Rumuola Road. Elekahia/Market Road, Woji/Old Aba Road, Olu Obasanjo Road, Elekahia/Market Roads, Woji/old G.R.A Road, Okporo Road, Cho/University of Port Harcourt Road, Eligban Road/Psychiatric Hospital Road and Aggrey Road/Churchill/ Harold Wilson Drilce.
Apart from the trunki A roads mentioned earlier, the feeder road also constitute major road Network in the metropolis. There are minor roads, which connect traffic with the feeder roads, these assist in knitting up the network of roads in the metropolis. The major roads and the feeder roads are the busiest in terms of traffic volume and commercial activities and this constitute major traffic generation and attraction corridors of the metropolis. The entire road network of the metropolis, has a length of approximately 150km of which 70%is paved”.
Table 2.5 below shows the level of vehicular fic within the metropolis as at 1997.
|Artilary Junction Aba Express||Education Bus stop||Aggrey Road||Garrison Junction||Total|
Source field work, 1997 William, Adumo (1998) “A survey of vehicular traffic in Port-Harcourt metropolis. Culled from Agbogomeh and Obot 1999.
Vehicular traffic in Port –Harcourt has tripplied in 2009 with it’s attended high commission of green house gases it has significant bearing on the temperature of Port-Harcourt-metropolis.
2.25 URBAN URBAN ECONOMIC ACTIVITIES AND ATMOSPHERI
Port-Harcourt is the second largest Port in Nigeria and it was meant to export coal and other industrial goods from upland areas to oversea countries (Adeyemo 1999). It is presently the operational head quarter of the Nigerian oil industry, the rapid growth of the city in recent years is associated with the expansion of the oil industry which has also attracted many manufacturing industries. Today Port Harcourt is one of the most industrialized towns in Nigeria Adeyemo (Ibid).
An earlier study of the economic activities in Port Harcourt metropolis shows that the informal sect of the economy grew by 38.45% this is closely followed by manufacturing activities with 22.36% by 1987, 52 manufacturing firms were register with the Port-Harcourt chamber of commerce and industry. This number rose to 210 in 1990 and in 1997, the number had risen to 512 (F.O.S, 1997) at a growth rate of 88.46% per annum between 1987 and 1997. This is understandable when one identifies the industrial base of Port Harcourt to be attractive to industrialist Adeyemo (op.cit).
In addition to manufacturing activities, other economic activities like trading also go one within the metropolis, Emenike (1999) reports that there are several Commercial Areas which include Mile 1-3 Market New layout market, silver valley and Rumuomasi-Rumobiakani Market area. There is also the prevalence of smaller markets scattered all over the metropolis.
The implication of high economic activities is the increase in the release of green house gases Associated with the production of green house gases by industrial plants and processes.
2.2.6 Ayoade (2009) describes earth’s atmospheric as a thin layer of Odourless, Colourless and tasteless gases held to the earth surface by ferces of gravity. The atmosphere comprises a stable mechanical mixture of gases, the most important of which are Nitrogen, Oxygen, Argon Carbondioxide, Ozone, and water vapor. The important thing in this composition is that these gases occur in the atmosphere at finite amounts which should not be altered, but urban economic activities alter the quantity of these gases within the atmosphere. Add those which normally should not be in the atmosphere they include C02 CH4, CFC, N20
2.2.7 IMPACTS OF URBAN HEAT ISLAND
It has been largely demonstrated that cities with variable landscape and climate can exhibit temperature several degrees higher than there rural surroundings, a phenomenon which of increases in the future, may result in a doublings of the urban to rural thermal ration in the decade(Nichol 2003). Elevated temperatures from UHI, particularly during dry season, can affect our environment and quality of life, while some impacts may be positive such as increasing or lengthing the plant growing season, the majority of them are negative they include.
- Increase in energy consumption
- Elevation emission of air pollution and green house gases
- Compromise human health and comfort
- Impaired water quality
- Increase energy consumption.
Increase in temperature associated with urban heat islands increase the demand for cooling. Research shows that electricity demand for cooling increases 1.5-2.% for every increase in temperature. In topical cities where energy generation is low, the use of alternative source of electricity such as generation is very high, which further increase the level of heat in the area. Akbari (2005). Urban hear islands increase overall demand, as well as peak demand, which generally occurs on heat weekdays afternoons, when offices and homes are running cooling systems, lights and appliances. During extreme heat events, which are exacerbated by UHI, the resulting demand for cooling can overload systems and require a utility instituted controls.
- Elevated emission of air pollution and green house gases.
The primary pollutant from power plants include sulfordioxide (co2) and mercury (Hg) Dixon and mote (2003).
These pollutants are harmful to human health and also contribution to complex air quality problems such as the formation of group-level ozone (5mog), fine particulate matter, and acid rain, increased use of green house gases. In addition to their impact on energy, related emission, elevated temperatures can directly increase the rate ground water-level ozone formation. Ground-level ozone is formed when N0x and volatile organic compounds from waste react in the presence of sunlight and hot weather. Kabari (2005).
- Compromised human-health and comfort.
Increased daytime temperature, reduced nighttime cooling and higher air pollution levels associated with UHI can affect human health by contributing to general discomfort, respiratory difficulties, heat cramps and exhaustion, non-fatal heat stork, and heart-related mortality.
Heat islands can also exacerbate the impacts of heat waves which are periods of abnormal hot and often humid weather. Sensitive population such as children, older adults and those with existing health conditions, are at particular risk from those events. Excessive heat events, or abrupt and dramatic temperature increases, are particularly dangerous and can result in above average rate of mortality. Research estimate that from 1979 to 2003, excessive death’s in the united alone (center for disease control and prevention 2006)
- Impaired water quality
High pavement and root tops surfaces temperatures can heat stormwater runoff. Test have shown that pavement that are 380c James (2002). This heated rainwater general becomes runoff, which drains the water temperature as it is released into streams, rivers, ponds and lakes, James (Ibid)
Water temperature affects all aspects of aquatic life, especially the metabolic and reproduction of may aquatic species. Rapid temperature changes in aquatic eco-systems resulting from warm rain water runoff can be particularly stressful, even fatal to aquatic life.
This chapter is primarily concerned with how data on various aspects of the research work was collected; it also described the statistical technique that was used in arriving at the sample size and date analysis.
- NATURE OF DATA
The data that was use for the analysis was collected from people’s views on atmospheric temperature in recent years, and also information from relevant temperature data collecting agencies.
- METHOD OF DATA COLLECTION
Data that was analysed in this research was gotten from two sources which are the primary sources and secondary sources.
3.1.2 PRIMARY DATA SOURCES
The primary data sources for this research was basically data collected at various land uses, using a minimum and maximum temperature, in addition to this questionnaires were administered to collect relevant information for the research.
3.2.2 SECONDARY DATA SOURCESES
The secondary data resources for this research involved data from the Nigeria meteorological Agency (NIMETH) and the ministry of Urban development, it also included an in-depth study of written documents on the subjects matter, among these where text books, Journals, Maps, Unpublished student projects and discussion with professionals.
3.2.4 SAMPLING TECHNIQUE/SAMPLE SIZE
In other to adequately collect sample from all parts in the study area, the research adopted the cluster sampling technique Oyegun (2003) using this method, the entire land uses found within the metropolis which include, high residential, low residential, commercial, industrial and recreational areas (Emenike, 1999) was given alphabet A.B.C.D and E respectively and using a map of the study area, the entire area was demarcated unto smaller areas, and a table of random numbers is to be collected from and at this points. Measurements were taken and questionnaire administered, the same method was use to collect data from Umuawa which is the rural area used for the control of the study. In due to the large size of the population only 303 questionnaires were administered in the study.
- METHOD OF DATA ANALYSIS
Before arriving at our concluding the date collected during this study was analyzed using several statistical tools which include percentages and mean. The first Hypothesis was tested using the lingering Regression Y’ = a=bx, and the decision rule for the test was .
“Reject Ho favour of Hiif the standard difference between the sample slope(b) and the Hypothesized population slope 0 falls into the rejection region that is t> 2.44 or < – 2.44 otherwise fail to reject” (sanders and smidt, 2000).
The second hypothesis was tested using the chi-square test
X2 = (0-E)2
“he decision rule was, accept the null hypothesis if the calculated value is greater than the critical value, otherwise fail to accept” (sander and smidt ibid)
PRESENTATION AND DISCUSSION OF DATA
This chapter shows the various results of the Measurements carried out, and the various test conducted on the sample and the Analysis or discussion of the results.
- DATA PRESENTATION
Table 4.1 Questionnaires Summary
|Zones of Allocation||Allocation||Questionnaires Refund||Not fund||Total|
|Low income Residential||80||75 (98%)||5 (6%)||80|
|High income Residential||80||70 (98%)||10 (13%)||80|
|Commercial||80||78 (98%)||2 (3%)||80|
|Industrial||80||80 (100%)||0 (%)||80|
A total of 320 persons where sampled through the use of a questionnaire. Out of which a total of 303 copies were retrieved. However, some of the retrieved copies were not used for the analysis due primarily to incompletion of the relevant questions asked and inconsistency in responses. A total of 298 copies where used for the analysis.
Table 4.2 Age of responded
Source field survey (2009)
The table above indicated that 31, 17, 23 and 2.9% of the respondent respective falls within the following age bracket, 18-25, 26-35, 36-45 above 45.
Table 4.3 sex of respondent.
Source field survey (2009)
Table 4.3 above shows that 57% of respondents were male while 43% were female.
Table 4.4 to verify in respondents live within the city
Table 4.4 above shows that 90% of respondent actually line in Port-Harcourt while 70% when visiting.
Table 4.5 residence of respondent.
|High income Residential Area||72||24%|
Source field survey (2009).
Table 4.5 above shows that 31% of respondents lived in low income settlements, 24% are from high incomes settlements 31% live around commercial areas while 14% about industrial areas.
Table 4.6 number of year’s respondent has been within the study area.
|Number of years||Frequency||Percentage|
|Less than 5 years||50||17%|
Source field survey (2009)
Table 4.6 above shows that 17% of respondent have lived less than 5 years in Port-Harcourt, 28% have been there between 6-11 years, 24% have been there between 12-17 years and 31% have lived in Port Harcourt for more than 17 years,
Table 4.7 people’s perception of the temperature of Port Harcourt metropolis.
|Hotter than normal||264||89%|
|Cooler than normal||0||0%|
Sources field work (2009).
The above table shows that 89% of the respondents though that the city was Hotter normal while 11% thought it was normal, 0% thought was cooler than normal.
Table. 4.8 shows the relationship between place of residence and atmospheric temperature perception.
|Place of residence||Perception and Frequency||Total|
|Normal||Hotter than normal||Cooler normal|
|Low income residential||13 (14%)||80 (86%)||0||100% (93)|
|High income residential||23 (32%)||49 (68%)||0||72 (100%)|
|Commercial||5 (5%)||87 (95%)||0||92 (100%)|
|Industrial||6 (15%)||35 (85%)||0||41 (100%)|
|Total||47 (16%)||251 (84%)||0||298 (100%)|
Source field survey (2009).
Table 4.8 above in trying to show relationship between the residents location and his perception of the heat situation within the metropolis show that 86% of those who live in low income areas thought that Port Harcourt is hotter than normal, 68% of those who live high income areas thought it was normal, 95% of those who live in commercial areas thought it was hotter than normal and finally 85% of those in the industrial thought it was hotter than normal, 13%, 32%, 5% of those who lived in these areas respectively thought it was normal.
4.9 prevalence of Heat rashes among respondents at different residential Areas.
|Low income Residential area||83 (89%)||10 (11%)||0||93 (100%)|
|High income residential||13 (18%)||59 (82%)||0||72 (100%)|
|Commercial||80 (87%)||12 (13%)||0||93 (100%)|
|Industrial||30 (73%)||11 (27%)||0||41 (100%)|
|Total||206 (69%)||92 (31%)||O||298 (100%|
Source field survey (2009).
Table 4.9 above reveals a high prevalence of Heat rasher among residents of low income commercial and industrial areas will those in high income are low.
- ANALYSIS: Testing of Hypotheses
- This is no significant relationship between land-use type, and atmospheric temperature variation in Port Harcourt metropolis.
Y’ = a+bx
Where b = n xy – ( ) ( )
N x2 – ( )2
a = ý – b x
where y = mean of the dependent variable
x = mean of the independent variable
Table4.10 showing values of land use type temperature
|Land use||X||Y oc||Xy||X2||Y2|
|High income residential||2||29.2||58.4||4||852.6|
|Industrial area||4||30. 2||120.8||16||912.0|
|Low income residential||5||32. 6||163||25||1062.8|
Y = 149.9 = 29.98 x = 15=3
b=5 (460.3) – (15)(149.9) = 23015.5-2248.5
= = 1.06 b = 1.06
a= y –bx
y1 = 26.8+1.06 ( ) ————————- (1)
Equation 1 above is the regression equation for the variables of study in the hypothesis.
Standard deviation Sy. x=
t= where sb=
= = = 0.18
t= = 5.88
From the calculation t=5.88, therefore we reject the null hypothesis which states there is no significant relationship between land-use type and atmospheric temperature. And accept the alternate hypothesis which state that there is a statistically significant relationship between land-use type and atmospheric temperature variation.
- There is no statistically significant difference between the temperature of Port Harcourt metropolis and that of its surrounding rural area.
O = observed frequency
E= Expected frequency
|Days of measurement||Temperature (degree Celsius)||Rural temperature (Degree Celsius)||Total||0||E||0-E||(0-E)2|
E=Row Total x colume total
Degree of freedom (df) = n-1 =25-1 =24
Calculated cHi-square value is 14.55, Calculated cHi-square value is 14.55, while the critical value is 36.4, at 95% confidence level and 24 degree of freedom. Since the calculated value is smaller than the critical (table) value we hereby accept the null hypothesis which states that there is no statistical difference between the temperature of Port Harcourt metropolis and that of its surrounding neighbouring areas.
- DISCUSSION OF FINDINGS.
In other to answer the questions put forward in the research, 298 questionnaires was sampled to get the residents perception of temperature situation within the metropolis, among those that responded 34 (11%) through that the city was normal as it has always being, 264 (89%) of those that responded through that the city is actually Hotter than normal, this situation is in line with the conclusion of the Nigerian meteorological Agency report (2007) which affirmed that port Harcourt is actually hotter especially in the evening.
Response collected in the process of the research showed that 86% of respondents in low income areas where of the view that the temperature of the city was hotter than normal, 95% of those who live in commercial and 85% of those in industrial areas finding is in line with Quattrochi (2007). After carrying out a research on atmospheric temperature over Atlanta city observed using satellite imagery that central business districts and high occupancy areas where hot spots or point of high temperature compared to other parts of the city.
This position is supported by Waugh (when) he explained that the closeness of buildings in the city and the building materials blocked horizontal air flow, and release heat absorbed in the day, leading to an increase in temperature over those Areas.
Responses collected from field survey also showed that those that live in central Business district had high prevalence of heat rashes and compared to those living in other higher income area, this position is explained by Dr. Peace Nimi of the University of port Harcourt Teaching Hospital to mean that these areas had higher temperatures incidence of heat rashes explained that most high income area are well built to encourage ventilation, and heat reduction.
During the case of the research, it was observed from temperature reading collected from the Nigeria Meteorological Agency that the temperature of Port Harcourt is increasing 0.5-2.5 degrees centigrade. This is due to the rapidly changing Landover, replacing natural cover with artificial ones. As has been show from available data in the research 66% of the entire city is used for residential from about 70% is low residential, 21.5% is for commercial and 12.2% for industrial with no regard for open spaces. This does not mean well for the city. it is also in my view that the temperature from the Nimet can be slightly higher considering the fact that Nimet readings are taken from Omagwa which is an outskate of town and can even be cooler that the actually port Harcourt city.
Also during the study two Hypothesis where tested, Hypothesis I, was to find out if a statistically significant relationship existed between land use type, and atmospheric temperature, subjecting this to statistical analysis using Regression equation, it was discovered that there is a significant relationship between land use type and atmospheric temperature variations, it was also observed during the study that recreational land uses has a cooling effect on the temperature of the metropolis due to the relatively low temperature around these areas.
Also another Hypothesis was tested to find out if there is a significant difference between the temperature of port Harcourt metropolis and that of its rural was surround, it was observed that the temperature of the rural was between 1.5-2.5 degree Celsius cooler than the urban centre, but when this was subjected to statistical test, the warming up of the urban centre have severe consequence on it surrounding rural areas
SUMMARY, RECOMMENDATION AND CONCLUSION
5.1 SUMMARY OF FINDING
This research which is aimed at uncovering the impact of land use change on atmospheric temperature variations in port Harcourt metropolis was born out of perceived increase in the temperature of port Harcourt as a result of change in land-uses and land cover, it was discovered that the central business district is actually hotter that it surroundings and that low income settlements showed signs of higher temperature than those of high income settlements, this actually contribute to an increase in temperature within the metropolis, this position is confirmed by temperature readings from Nimet and from other similar research carried out in a similar city, the research noticed high rate of occurrence of temperature related ailments among residents of low income settlements.
In view of the fact that our research have discovered that the city of port-Harcourt is heating up and unless something drastic is done, we are heading to a very disastrous future, it is our recommendation in other to curb the menace. The following should be considered
The government should as a matter of urgency put in place measure that will ensure that, land developers do so in respect of relevant town planning laws, that is to say that people should not allow to build houses at random, and adequate spacing should be provide between buildings to aid ventilation.
- PLANT TREES AROUND THE METROPOLIS
The present effort of the government of greening the city should be sustained; trees should be planted along streets and in compound in other to act as carbon sink, and as wind breaks, to help regulate the temperature of the metropolis.
- PROVISION OF PARKS
It has been proven that parks are natural surfaces that help reduce temperature; it is therefore encouraged within the metropolis at strategic locations.
iii. ENCOURAGE NATURAL SURFACES
Instead of covering the surfaces of the compounds with cement. We recommend that he surface of the compounds should be left bear and green
This research has attempted to investigate and assess the impact of land-use change on atmospheric temperature variations in Port Harcourt metropolis. The effort has presented the current state of the literature of the problem as it relates to the topic under study.
The research has also found substantial evidence to show that the temperature of Port Harcourt metropolis is increasing, and this is due to the change in land use/land cover in the metropolis.
The author recommended that the authorities should regulate the rate at which buildings are erected in the metropolis and ensure that they are built in accordance with the laid down laws, we recommend that parks should be developed around the metropolis, the government should put in place regulations that will restrict the rate at which natural surfaces re replaced with pavements.
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