The evidence of Rainfall and Temperature
trend is recognized by today’s world as one of the important
environmental problems that affect humanity.It refers to a serious and
continuous change in weather pattern, largely attributed to the emission
of greenhouse gases such as carbon dioxide, methane, nitrous oxide and
water vapor by humans, mainly produced from thetransport, agriculture,
manufacturing and energy sectors of the economy.
Recent changes in climate have led to
warmer temperatures, heavy rainfall, drought, and floods etc.
(AkinsanolaandOgunjobi, 2014).Therefore, the knowledge of climate
variability over the periodof instrumental records and beyond on
differenttemporal and spatial scale is important tounderstand the nature
of different climate systems andtheir impact on the environment and
society (Oguntundeet al. 2012).
Climate variability is the variations of
the normalstate and other statistics of the climate on all temporal and
spatial scales beyond that of individual weatherevents. Variability may
result from natural internal processes within the climate system
(internal variability)or from anthropogenic external forces (external
variability) (IPCC 2001, 2005). The global climate has changed rapidly
with theglobal mean temperature increasing by 0.7oC within
thelast century (IPCC 2007). However, the rates of changeare
significantly different among regions (IPCC 2007).This is primarily due
to the varied types of land surfaces with different surface albedo,
evapotranspiration andcarbon cycle affecting the climate in different
1.1 BACKGROUND TO STUDY
The Niger Delta is a very sensitive area
housing several ecosystems or local biomes. This has made it
particularly vulnerable to little changes in environmental conditions,
weather variability inclusive. Apart from the generalized effects of
climate variability, there are certain impacts that are either unique to
or more pronounced in the region. Some of these are discussed below.
1.1.1 Coastal Erosion and Flooding
The Niger Delta region is a coastal
environment in which Warri is a major city with high rate of petroleum
exploration activities. Increased flooding and aggravated erosional
activities have been reported in the coastal regions and these have been
linked with global warming by the IPCC. According to the IPCC (1990),
working with records over the last 100 years, have shown that a strong
correlation exist between greenhouse gases emission and climate change
and between global temperature and sea level rise. Global temperature is
expected to rise by between 0.2oC to 0.5oC per
decade. The rise in temperature is expected to cause thermal expansion
of sea and melting of polar ice. These will cause the sea level to rise
for about 3-10 cm per decade during the next century. In some places,
especially in Forcados, some oil wells have been lost to the ocean due
to erosion. Apart from coastal erosion, flash flood in general has
impacted negatively the livelihood of many communities within the Warri
environ as a result of excessive rainfall. Flood and erosion remove top
soil, destroy roads, affect fresh water resources and threaten lives and
properties. Many people have been rendered homeless by floods and
several roads have been made impassable.
1.1.2 Change in Rainfall Pattern
Meteorological data have shown that
rainfall pattern in Nigeria has changed in the past decades. Oladipo
(1995) reported that the decline in rainfall in Nigeria started at the
beginning of the 1960s when a decade of relatively wet years ended.
According to him, the persistence of below-mean rainfall in the last two
decades in Nigeria is an indication of an abrupt change in climate. The
Niger Delta lie predominantly in the tropics having two seasons – the
wet and dry seasons. The wet season occur from May to September, while
the dry season begins in October and ends in April.Food security has
been defined as the ability of people to grow and obtain food. The
agricultural sector in Nigeria is highly sensitive to rainfall pattern.
It has been predicted that climate variability orchange will pose
serious threat to food security. Climate change creates uncertainty in
the rainfall pattern (timing and amount) and affects agricultural
Agriculture in the Niger Delta is highly
dependent on rain and irrigation is seldom practiced. The changes in
the rainfall pattern have greatly affected the agriculture in the
region. Farmers in the region begin cultivation at the end of the dry
season, when the rain begins to fall. They plant their crops after the
first or second rain in the month of March, and sometime in April. After
the first rain, the rain falls periodically till the months of
June/July (the peak of the rainy season), when rain fall more or less
continually. The periodic rainfall pattern before the peak in June
enables farmers to cultivate various crops. Because of the change in
rainfall pattern, farmers who plant after the first or second rain in
run into huge loss when the rains are delayed beyond the usual due to
climatic changes. The crops are scotched causing huge economic loss.
Before this time farmers can predict the rain and they know precisely
when to plant their crops. The crops after they are planted are watered
periodically by rain before the peak of the rainfall in June. The amount
of rainfall within the period before the peak is necessary for the
optimum performance of many crops most especially the maize which is
widely consumed in every part of Nigeria. (Etiosa and Mathew 2007.)
1.1.3 Vegetation Loss
One important feature observed in the
study region is the gradual disappearance of primary forests (Etiosa and
Agho 2007). This may be partly due to climate change and partly due to
human activities. Uncontrolled logging, agricultural activities, acid
rain, oil exploration and exploitation, urbanization and mining
activities contribute to lose of vegetation. The vegetation of some part
of the Niger Delta is dominated by grasses, sedges and shrubs with few
scattered trees and they were mainly palm trees. In other parts, trees
grow close to one another to form thick canopy over undergrowths.The
Niger Delta region of Nigeria which contains one of the highest
concentrations of biodiversity on the planet could experience a loss of
about 40% of its inhabitable terrain in the next thirty years. As
majority of the people living in the Niger Delta are farmers, the
environmental and social consequences of climate change is putting
livelihoods at serious risks.
1.2 STATEMENT OF THE PROBLEM
The impacts of climate change together
with rising world population enact a serious threat to all vital sectors
of the world economy. Recent concern about rising global temperature
was justified by its negative impact in all sectors of the economy most
especially water supply, ecosystems, coastal habitats, industries,
health and agriculture sectors. Findings from several studies (Anuforom,
2010; BNRCC, 2011; Farautaet al., 2011; Odjugo, 2010; UNDP
2010) predicted a temperature rise of 1.5 0 to 2.5 0 C for Nigeria in
the 21stcentury. The threat has serious negative consequences for all
sectors of the economy.
The major climatic challenge prone to
the Warri environment is the Flash Flooding which occur more often after
an excessive rainfall in which increasing flood risk is now being
recognized as the most important sectoral threat from climate change in
most parts of the Delta region which has prompted public debate on the
apparent increased frequency of extreme, and in particular, on perceived
increase in rainfall intensities (Oriola, 1994).
This observed challenge is
creatingincreased uncertainty about future temperature andprecipitation
regimes which makes investments inagriculture and other
weather-dependent livelihoods inherent more risky (FAO, 2008) in study
Based on this background, this study
attempts to ascertain the degree of variability of weather pattern in
Warri, Delta State, in a bid to understanding, managing and possibly
predicting the aforementioned related challenges thereby providing an
empirical basis for the formulation of effective adaptation and
1.3 SIGNIFICANCE OF THE STUDY
Temperature and rainfall trend detection
is an important exercise that can provide an indication of the
magnitude of climate or weather variability providing a clear picture of
the impact in the trends of the study area and a prerequisite for
developing a framework for mitigation and adaptation policies. The
knowledge of temperature and rainfall trends in the study area has
tremendous potential benefits some of which can be highlighted as
- It will bring to limelight the potential effect of climate variabilityin Warri city
- It will enlightenrelevant authorities and residents on applicable adaptation measures
- It will provide empiricalbasis for the formulation of effective mitigation policies
- The project work will serve as an indispensable and valuable data
for students, academics and future researches who might be interested in
validating their findings in similar settings
1.4AIM AND OBJECTIVES
The Aim of the study is to examine the trend of rainfall and temperature in Warri, Delta State.
The objectives of the research are:
- To ascertain the temperature and rainfall trend in Warri, Delta State
- To discern with certainty the significant changes in temperature and rainfall trend in Warri, Delta State
- To uncover the implications of observed trend and variations in temperature and rainfall trend in Warri, Delta State
1.5 STUDY AREA
1.5.1 Location and Position
The study area, Warri, has its
geographical coordinates as 5°31′N5°45′E/5.517°N 5.750°E/5.517; 5.750 (
Ekeh and Palmer 2005).Warri is a city in Delta State, Nigeria.
It is an oil hub in South-South Nigeria and houses an annex of the
Delta State Government House .Warri city is one of the major hubs of petroleum activities and businesses in the southern Nigeria. Delta state, southern Nigeriais bounded by Edo state to the north, Anambra state to the east, Rivers state to the southeast, Bayelsa state to the south, the Bight of Benin of the Atlantic Ocean to the west, and Ondo state to the northwest. On the east and south the state is bounded by the lower course and delta of the Niger River.
Delta State currently has twenty-five
local government areas. They are: Aniocha North, Aniocha South, Bomadi,
Burutu, Ethiope East, Ethiope West, lkaNorthEast, lka South, Isoko
North, Isoko South, Ndokwa East, Ndokwa West Okpe, Oshimili North
Oshimili South, Patani, Sapele, Udu, Ughelli North, Ughelli South,
Ukwani, Uvwie, Warri North, Warri South and Warri SouthWest.
It is a commercial capital city of Delta
State, with a population of over 311,970 people according to the
national population census figures for 2006. The city is one of
cosmopolitan cities in southern Nigeria comprising originally of Urhobo, Itsekiri and Ijaw people.
The climatic condition of Warri region
experiences moderate rainfall and moderate humidity for most part of the
year. The climate is equatorial and is marked by two distinct seasons:
the dry season and the rainy season. The dry season lasts from about
November to April and is significantly marked by the cool "harmattan"
dusty haze from the north-east winds. The rainy season spans May to
October with a brief dry spell in August, but it frequently rains even
in the dry season. The area is characterized by tropical equatorial
climate with mean annual temperature of 32.8 °C and annual rainfall
amount of 2673.8 mm. There are high temperatures of 20 °C and 29.6 °C.
The natural vegetation is of rainforest with swamp forest in some areas.
The forest is rich in timber trees, palm trees, as well as fruit trees.
Warri in Delta State is a part of the
Niger Delta Structural Basin in which three major sedimentary cycles
have occurred since the early Cretaceous. The subsurface stratigraphic
units associated with the cycles are, the Benin, the Agbada and the
Akata Formations (Kogbe, 1976). The surface rock throughout the state
consists of the OgwashiUku formation. The Benin formation is about 1800m
and consists of loose and unconsolidated sands.There is little
hydrocarbon associated with it. The underlying Agbada Formation which
consists of sandstone and shales is, however, rich in hydrocarbons. It
is up to 3000m and is underlain by the Akata Formation. The OgwashiAsaba
Formation that underlies the northeast consists of an alternation of
lignite seams and clay.
Warri is a region built up by the
sedimentation of the Niger Delta and consists of the delta in various
stages of development. Four major physiographic units are identifiable
with in it. First, the freshwater swamp which is the most active area.
It is located close to the River Niger, where annual flooding and
deposition occurs up to 45 km from the river's course.
Second, the man grove swamp area
described as an intermediate delta stage. It is much lower and a great
proportion of it is brackish, having been invaded by the sea since large
amounts of freshwater have ceased flowing into it. Third, the upland
and swamp, which is also called the coastal plain.
It lies between the flood plain and
Benin lowlands. The swamps are more restricted to broad drainage
channels created when this area was an active delta. Fourth and finally,
the upland Niger valley, which is a narrow strip above the delta and
relatively flood free.
1.5.6 Ecological Problems
The environmental setting of Warri,
Delta State has very serious ecological problems such as erosion and
flooding. Coastal and creek erosion affect the coastal areas, resulting
in loss of farm and residential land, and in some cases whole village
such as Ogulaha and Ugborodo (Ibe,1988).
Flood is a widespread phenomenon in the
state. In the coastal area, the numerous rivers and creeks flood their
banks creating social and economic problems. Flash floods and flood
pondages are the major features of the drylands, especially in the urban
centre of Warri, Sapele and Ughelli.
In recent times, oil exploitation and
gas flaring have further aggravated the ecological problems, causing
very serious environmental pollution. The consequences include the
destruction of aquatic life and vegetation and reduction in soil
1.5.7 Socio-Economic Activities
Warri is the economic heartbeat of Delta
State, being the divisional headquarter for ShellPetroleum Development
Co-operations (SPDC), also a swamp location for exploration
andproduction of oil for SPDC. Other oil companies as well as oil
servicing companies are alsosituated in the town.Major industries in the
area are oil mining, oil servicing, petro- chemicals and sculptural and
bronze making establishments.