Urbanization and Environmental
Stress: A Review of Impacts of Urban
Development on the Environment in Kenya
George Ouma Ochola*
Department of Agronomy and Environmental Studies, Rongo University, Kenya
Submission: August 21, 2018; Published: September 21, 2018
*Corresponding author: George Ouma Ochola, Department of Agronomy and Environmental Studies, Rongo Kenya,
How to cite this article: George Ouma Ochola. Urbanization and Environmental Stress: A Review of Impacts of Urban Development on the Environment
in Kenya. Int J Environ Sci Nat Res. 2018; 14(2): 555889. DOI:10.19080/IJESNR.2018.14.555889.
Urbanization has been considered a development process which is beneficial both to individuals and the country at large. People move from rural to urban areas in search of better services like education, jobs, and recreational services among others. Urbanization draws various activities like industrialization, tourism, educational and health facilities which not only contribute revenue to the government but also create employment opportunities for the jobless which in turn reduces crime rates associated with joblessness. Despite the benefits that accrue from urbanization, it has been characterized by loss of vegetation cover, degradation of surface water quality, land degradation, more generation of waste, air pollution, poor infiltration, noise among other impacts. These impacts if left unmonitored, generally degrades the quality of the environment. The study was informed from such argument to examine the impacts of urbanization on the environment. It relied on document analysis as a method of data gathering.
Keywords:Urbanization; Impacts; Environment; Stress; Kenya
Human development activities are beneficial to him but have a lot of impacts on the environment. As has been mentioned by previous scholars, environment means a lot to humanity together with other life forms. Environment support various human activities such as agriculture, settlement, industrial and other forms of development activities. Sustainable use of environmental resources has been an issue of debate globally . Every individual on earth wants to develop. Human development in most cases has not integrated the environmental concerns. This has led to degradation of environmental resources which are meant to cater for both present and future generations. The value of environment has been slighted and hence man undertake development activities without giving attention to the impacts of his activities. This paper examine urbanization as a development activity together with the impacts it has on the environment.
Urbanization has been viewed as a development activity which is associated with transformation and growth of urban areas into cities. It involves migration of people from the rural into urban areas. Urbanization draws and comes with various activities that support human’s life in different ways. People get moved and attracted with better health, education, recreational
services in the urban areas . Similarly, they move to urban centres in search of job. Growth of urban population comes with consequences such as increased demand for housing facilities, more educational and health facilities together with other facilities which support human’s life . It also calls for more resources such water, land and energy to be subjected into use.
Urban development has considerably affected water resources especially the surface water bodies. Urbanization is associated with industrial development and some of them came up as a result of establishment of industries. Availability of water supply is one of the factors that influence the establishment of industries. Apart from the direct impacts which might come from the industries such as discharge of effluents into water bodies and over withdrawal of water for industrial use, development of urban centres impact negatively on surface water . As urban centre draws people from every corner of the country, increase of its population translates to increased waste product which sometimes deposited into water body. A good example is Nairobi River which some people settling adjacent to the river have turned it into dump site. River Migori also suffers the same problem as a result of development of Migori town. A number of rivers including Sare, Ewaso Nyiro among others experience similar challenges.
In most cases, water has been considered life. Human
beings together with other organisms need fresh water. Once
contaminated, water becomes unhealthy and unsafe for
consumption. The waste deposited into the rivers as a result of
urban development degrades the quality of the water and make
it unsafe even for the aquatic organisms supported by such rivers
. These aquatic organisms suffer from the contaminants of the
waste and may end up dying. If this happens, we realize loss of
biodiversity. Through urbanization, pavements are constructed
to enable easy movement and save people form muddy areas.
These pavements interferes with water infiltration into the
soil. This not only affect the soil moisture and micro-organisms
but also impacts on the ground water recharge. Sustainably,
there should be constant flow of water in the cycle . If one
stage of water cycle is impaired, the whole system/process is
impacted on. The water that fails to infiltrate the soil as a result
of pavements created may end up contributing to flooding.
Urban development also leads to over-extraction of ground
water resources. Having contaminated the surface water
declared it unsafe for consumption, man starts exploring the
ground water. Several boreholes are drilled to support the everincreasing
urban population whose demand for water also
increases. This leaves the government together with private
developers with no alternatives other than drilling boreholes.
They pump underground water and supply it through pipes.
This interferes with the normal water cycle especially if overwithdrawn.
The other impact of urbanization on water resources come
due to the establishment of the drainage systems like the sewer
lines. This might not have frequent impact but when they bust or
have leakages, may cause a significant impact on water quality
. The sewage may contaminate the ground water as well as
the surface water as it flows down-stream. Such an impact on
water quality may be compared with the impacts of improperly
treated industrial effluent on water. It may contain heavy metal
that might be very harmful to the aquatic ecosystem.
Urban development and expansion involve clearance of
vegetation to pave way for settlements. This subjects land to
agents of erosion. Vegetation cover normally controls soil erosion
and infiltration rates. They lower the speed of flowing water
(run-off) making it infiltrate the soil. Other roles performed by
vegetation include contribution to hydrological cycle through
evapo-transpiration, acting as carbon sinks, addition of aesthetic
value among other roles . These roles are compromised when
vegetation is cleared. The sad news is that urban population
continues to increase and more houses are needed to cater for
the increasing population. This means that more vegetation will
continue to be cleared. Vegetation also act as habitat for animals
like birds among other life-forms. Destruction of vegetation
implies loss of habitats. The animals are displaced and might
migrate to other areas which might also be unsafe for them.
Oyugi et al.  established the high rate of land cover loss
especially in Nairobi. More settlements are created to help cater
for urban population. Some areas serve as communication lines
e.g. roads that also contribute to loss of vegetation cover. Figures
1 & 2 show the differences experienced between 1988 and 2015
in terms of loss of land cover as was established by Oyugi et al.
. Significant land cover changes have been realized in Nairobi
City since 1988. The city has expanded, a lot of settlement have
come up together with industrial activities which have negatively
impacted on land cover. Aesthetic value of the land cover has
been lost. Structures have replaced vegetation. The quality of
air continually goes down in that air purification reduces with
reduction in vegetation cover. Need for food by urban dwellers
also cause pressure in other regions such as the peri-urban and
rural areas. Urban centres create ready market for food produce.
People in the rural areas subject land to agricultural activities
that involves clearance of vegetation to pave way for farming
activities. Through such activities, land cover is lost hence
compromising their ecological roles. This is also accompanied by
soil degradation due to application of inorganic fertilizers which
not only infers with the soil pH but also impact on the soil microorganisms
meant for soil aeration. It is through such agricultural
activities where we realize eutrophication.
Urbanization has led to changes in land use. Open spaces
serving as recreational areas are being turned into built up
environment being occupied by settlements. Open grass, range
and shrub-lands supporting various biodiversity are also turned
into built environment leading to loss of biodiversity. A good
example was established when Nairobi city was subjected to a
study in 2017 to determine how fast urban development lead
to land use and land cover changes. The following results were
From Figure 1, it is evidenced that the range lands and shrubs
marked yellow was wide spread in the year 1988. The urban
built up environment as indicated by red was also not intensive. The forests marked green was still dominating and could be seen
distributed in the city. As urban population increased together
with other urban activities, the range lands and shrubs together
with forest started depreciating. More land cover was lost as the
urban built up areas increased as depicted in Figure 2.
Nairobi city as an example of urban development has now
been characterized by intense loss of vegetation cover and
increased coverage of the built-up areas which serve various
purposes such as business enterprises, industries, road networks,
residential structures together with other forms of settlements.
The city has subjected Nairobi river to a lot of challenges of waste
assimilation until the river has been overwhelmed and turned
into a sewage like system. It has been overburdened by waste
that is deposited in it. The areas that were formally occupied by
vegetation have also been replaced with structures. The range
and shrub lands have been lost Oyugi et al. . The percentage
losses are as indicated in Table 1. It might not reflect the current
situation on the since the data reaches 2015 but going by the
trends, it is on the constant increase. From Table 1, it is clear
that the built up environment increases yearly. This implies that
more land under range and shrub lands are being converted into
built up lands. Man has taken the initiative of finding how to live
comfortably without integrating environmental concerns in his
The environment get degraded at a faster rate as depicted
by this table. The natural environment is turned into
built environment and the ecological performed by these
environmental resources end up being compromised at the
expense of human well-being . What might have not known
is that we cannot talk about our well-being and development
if we leave environment behind. All that we do to realize wellbeing
takes place in the environment. Our developments are also
supported by what the environment provides . It is needless
to emphasize the importance that accrue from these resources
that we degrade and deplete because the impact of degrading
and depleting them is realized basically on us. Every individual
aim’s at having a better future. This cannot be achieved without
environmental resources that we don’t care for at the moment.
Urbanization should be controlled and planned so as to minimize
its negative impact on the environmental resources.
Proper environmental management should be encouraged
by embracing development control systems and adhering to
the provisions of the Kenyan Physical Planning Act and the
Environmental Management and Coordination Act which
advocate for subjection of new projects to environmental Impact
Assessment to help anticipate the potential impacts a project
might have on the environment thereby proposing mitigation
measures for environmental protection. Lack of follow up and
enforcement of these policies and other institutional frameworks have made private developers to take advantage and manage the
environmental resources as if they are individual properties
[7,8]. Figure 3 shows how range and shrub-lands are constantly
being lost in urban areas like Nairobi. The built up is on the rise
and will continue to go up as urban population continues to go
up . Rise of forest cover was experienced between 1988 and
1995 after which it started declining and has not risen to the
level it was in 1995. More pressure is caused by urban population
that majorly use charcoal as a source of energy for cooking in the
developing countries like Kenya.
Most of the changes in land use are triggered by urban
population which not only needs food but also other better and
quality services like housing . Planning issues also come with
their consequences. For example, planning of urban centres
provides for zoning to ensure conforming and compliance like
the type of enterprises to be found within the central business
district and other transitional zones. This might also be affected
by the differences in social structures and status. The urban rich
people with tend to acquire land far from the city centre. As they
move farther urban centre expands as more services also move
to where they occupy . The increase in urban population as
had been mentioned calls for a number of activities and service.
The World Bank established in 2016 under their report on
Kenyan urbanization review that the Kenyan Urban population
continues to rise and they also projected this to continue as
depicted by Figure 4.
As indicated in Figure 4, the rural population continues
to go down while the urban population rises. More people as
was noted by the World Bank  continually migrate to urban
areas. Urban environment becomes overwhelmed with waste
generated together with the pressure on the available resources
to meet the demand of the urban population. The constant
growth of urban population was also affirmed by Oyugi in 2017
whose study was based on Nairobi City and revealed a constant
positive rise in urban population as reflected in Table 2. The
World Bank estimate of the Kenyan urban population puts it at
slightly above 14million of which it is expected that by 2030,
the urban population will rise to 22 million and to 40 million
by the year 2050 . This signifies the pressure the urban
environment will have in terms of providing for this population.
Going with these estimates, very little natural environments
will be found. More areas will be turned into built environment
[7-9]. The country will keep on experiencing land use and land
cover changes. This calls for adoption of better environmental
management strategies that will counter the negative impacts
that will be associated with these changes that will come as a
result of urbanization. Increase in urban population is not only
estimated to rise in Kenya but globally as depicted in Figure 5.
This means that the impacts of urbanization on the environment
is a global agenda.
Kenyan urbanization has been seen to grow steadily.
According to Figure 6, it is indicated that 26.49% of the Kenya’s
population (total) already lived in cities and urban areas in the
year 2017. This is expected to have risen in 2018 considering
the trend in growth of urban centres . The only question that is still left unanswered is whether countries will put up
the right strategies in dealing with the environmental impacts
associated with this high rate of urbanization. It is clearly
indicated from Figure 6 that each year there is an increase in
urbanization. Some of the trading centres grown into urban
centre and transform the natural environment into built up
environment. The consequences of such kind of transformation
has been discussed above including loss of vegetation cover,
increased land degradation, changes in land use which impact
negatively on the environment. Others also include degradation
of air quality as vegetation which aid in purification is cleared
thus such a role they perform is compromised.
Most industries are found in urban areas. Among these
industries, some have not taken the initiative of being
environmentally friendly. They have installed carbon filters
which help monitor the amount of carbon dioxide and other
gases getting into the atmosphere. Consequently, the air get
polluted with these gases emitted from industries . Some
of the industries also deal with processing of poisonous items
which if not well managed affect the surroundings. The exhaust
fumes from vehicles whose number continue to rise in the urban
areas is also a threat to the environment as they pollute the
system. Urban areas are also characterized by noise pollution
which comes from industries and moving vehicles.
The impacts of urbanization on the environment cannot
be overemphasized. A lot of land cover has been lost through
urbanization, land use changes have been realized and more air
pollution have also been experienced. A number of rivers have
lost their quality due to urban development. The only challenge
that still persist is constant increase in urban population that
continues to put pressure on available resources like water.
More land is subjected to development. Land fragmentation and
settlements created which cannot perform the ecological roles
performed by the vegetation they substitute. There is therefore
need for controlled and urban development. Environmental
concerns need to be integrated in the development plans as
provided by the Physical planning act and the Environmental
management and Coordination act to help ensure environmental
protection and conservation of natural resources.