ABSTRACT
The study examined the effects of
drainage networks on floods in Calabar metropolis, Nigeria. The rapid increase
in urbanization without corresponding infrastructures in the city of Calabar
has led to increased incidences of flood as the available drainage channels
cannot contend with the volume of storm water. In view of this, the study
established gauging stations for the measurement of drainage run off using
measuring steel tape. And the volume of flood water was measured using stop
watch method (Velocity of flow) and copies of questionnaire were administered
to 400 households proportionally to the seven sample units. In view of the study
objectives, it determine the relationship between drainage width and depth and
floods. In addition, varied descriptive statistics tools were used to give a
spot on assessment and understanding of the variables of interest. In view of
the response of the gauging and physical measurement, it was established that
Calabar experience heavy rainfall due to poor drainage facilities The result
revealed that about 47% of the respondents said flood occur every year in their
zone and 41.75% said it occurred most parts of the year. The frequency of flood
is compounded with it’s intensity as over 59% of the sampled population agreed
that flood of the sampled population agreed that flood intensity is very high
in Calabar. The result further showed
that the factors of flood occurrence in the study area is linked to heavy
rainfall (26.3%), inadequate drainage channel (22%) poor physical planning
(15.5%) among others. On the perceived causes of inadequate drainage channel,
the result indicated that abuse of land use plans (28.7%) was a major factor
followed by poor monitoring and evaluation of project (21.5%). the study also
revealed that the drainage were very narrow and shallows as shown in frequent
floods in the city. The incessant flood often leads to water inundating compounds
(64.5%), preventing people from going out (11.25%), distortion of the scenic
beauty of the environment (6.25%), landslide (4.75%). Based on these findings,
the study recommended that since Calabar is located in a tropical zone
characterized by heavy rainfall the government should take proactive measure to
mitigate storm water. The present drainage systems should be cleared with
shovel by the people on a regular basis to allow for a free flow of storm
water. State department of town planning should live up to their bidding by
ensuring total compliance to urban ordinance to forestall incessant floods and
destruction of properties in the city of Calabar.
CHAPTER ONE: INTRODUCTION
BACKGROUND TO THE STUDY
Cities the world over are the dominating forces in
the organization of human population. As the world most crowded places, cities
continue to show increase in urban population. This increase leads to a growing
urbanization trend. Duru and Nnaji (2008) defined urbanization as the increase
in the population of cities in proportion to the region‟s rural population.
Urbanization is the outcome of social, economic and political developments that
lead to concentration and growth of large cities, changes in land use and transformation
from rural to metropolitan pattern of organization and governance. Rapid growth
of towns and cities has been common feature of the developing world (Aderamo, 2008).
Although urbanization is the driving force for
modernization, economic growth and development, there is increasing concern
about the effects of expanding cities, principally on human health, livelihoods
and the environment. The implications of rapid urbanization and demographic
trends for employment, food security, water supply, shelter and sanitation,
especially the disposal of wastes (solid and liquid) that the cities produce
are staggering (United Nations Conference on Environment and Development,
1992). The process of urbanization is believed to be connected with levels of
development and some assert that, for a country to develop there is the need
for an increased level of industrialization as it is generally accepted that
there cannot be urbanization without rapid economic growth (Tettey, 2005). The
pattern of urbanization in developing countries, particularly Africa, however,
is creating some concern that it may be generating a lot of development
problems in the process of its growth.
One of the daunting challenges facing African
countries in the wake of unprecedented urbanization during the last few decades
is the planning and management of physical infrastructure and the urban environment. As urbanization gathered pace
in most developing countries, the problem of inadequacy of infrastructure
services and deteriorating urban environment became enormous (Sule, 2009).
These problems range from poor housing conditions, inadequate infrastructure,
to squatter settlements (Arimah, 2002).
Spurred by the oil boom prosperity of the 1970s and
the massive improvements in roads and the availability of vehicles, Nigeria
since independence has become an increasingly urbanized and urban-oriented
society. During the 1970s, Nigeria had possibly the fastest urbanization growth
rate in the world (Sule, 2009). Because of the great influx of people into
urban areas, the growth rate of urban population in Nigeria in 1986 was
estimated to be close to 6 percent per
year, more than twice that of the rural population. Specifically, while only 7%
of Nigerians lived in urban centers in the 1930s, and 10% in 1950, by 1970,
1980 and 1990, 20%, 27% and 35% respectively lived in the cities (Okupe, 2002).
Over 40% of Nigerians now live in urban centers of varying sizes. Like other
developing countries, the rapid growth in urban areas in Nigeria is a „sword of
two edges‟ (Sule, 2009). While increasing human capital increased the economic
status of the country, the growths of large centers had outpaced government
capacity to meet the increasing demand for the provision of basic
infrastructural facilities and services. These are manifested in poor
investment in roads, housing, water supply, electricity, waste disposal
mechanisms, adequate drainage systems etc. (Sule, 2007; Aderamo, 2008; Jimoh,
2008). These problems have continued to persist and made worst due to
non-compliance to planning ordinances (Sule, 2010). Appropriate management of
drainage systems requires knowledge relating to the system boundary, system
resources, interactions between adjacent systems and allowable limits, or
thresholds, for each resource. Each of these elements will be unique to the particular system under
consideration, and each system must be assessed on its own merits.
Flooding has been identified as one of the major
factors that prevent Nigeria growing population of city dwellers from escaping
poverty and stands in the way of United Nations goal of achieving significant
improvement in the lives of urban slum dwellers by 2020 (Action Aid, 2006)
Nigerian coastal cities are daily inundated with
flood waters, and millions of properties have been destroyed and lives lost
(Eze, 2008). Poor drainage systems are often associated with street flooding,
and this has become critical environmental problems in coastal cities of
Nigeria such as Lagos, Port Harcourt, Ondo, Warri, Uyo, and Calabar (Eze,
2008). These towns which are quite close to the Atlantic Ocean experience heavy
flooding especially during the rainy season. However, it is not waters from the
Ocean that usually floods these cities but the heavy rains, and the low nature
of the topography and the poor drainage networks. Aderamo (2008) listed land
use problems, increased paved surfaces, river channel encroachments, poor waste
disposal techniques, physical development control problems, gaps in basic
hydrological data and cultural problems as major causes of street flooding in
Nigerian cities.
STATEMENT OF THE RESEARCH PROBLEM
Worldwide, there has been a rapid growth in the
number of people killed or seriously impacted by storms and floods and also in
the amount of economic damage caused; a large and growing proportion of these
impacts are in urban areas in low- and middle-income nations. For instance, in
Nigeria, flooding affected more than three million people in selected urban areas
between 1983 and 2009 (Environmental Management Disaster Database). Poor urban
infrastructural development and planning is likely to have been a factor in
much of this, but even if it was not, it is proof of the vulnerability of urban
populations to floods and storms whose frequency and intensity is likely to
increase in most places.
Henderson (2004) revealed that the level of risk and
vulnerability in urban areas of developing countries is attributable to
socio-economic stress, aging and inadequate physical infrastructure. Indeed,
according to Satterthwaite, Mark, Saleemul, Reid and Romero (2007), hundreds of
millions of urban dwellers have no all-weather roads, no piped water supplies,
no drains and no electricity supplies; they live in poor quality homes on
illegally occupied or sub- divided land, which inhibits any investment in more
resilient buildings and often prevents infrastructure and service provision. A
high proportion of this are tenants, with very limited capacities to pay for quality
housing – and their landlords have no incentive to invest in better- quality
buildings. Most low-income urban dwellers face serious constraints in any
possibility of moving to less dangerous sites, because of their need to be
close to income-earning opportunities and because of the lack of alternative,
well-located, safer sites.
Douglas et al (2008)
also report that many of the urban poor in Africa face growing problems of
severe flooding; they further buttressed the fact that increased storm frequency
and intensity related to climate change are exacerbated by such local factors
as the growing occupation of flood plains, increased runoff from hard surfaces,
inadequate waste management and silted up drainage.
Askew (1999) reiterated that floods cause about one
third of all deaths, one third of all injuries and one third of all damage from
natural disasters globally. Generally, flood events are attributed to global
warming, climate change, ocean swell/surge and torrential rains. Although flood
hazards are natural phenomena, damage and lose from floods are mostly the
consequences........
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Item Type: Postgraduate Material | Attribute: 87 pages | Chapters: 1-5
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