Time Series Analysis on Rainfall Pattern in Calabar Municipality From 2002-2014; A Case Study of Nigerian Meteorological Center Calabar
Chapter One
Objectives of the Study
- To study the pattern of rainfall in calabar municipality.
- To know if rainfall pattern affects tourism and economic development.
CHAPTER TWO
REVIEW OF RELATED LITERATURE
Introduction
This chapter presents review of related literature on a time series analysis on rainfall pattern in Calabar Municipality from 2002 – 2014 with a particular reference to Meteorological Centre Calabar. Views and opinions of other authors will be presented as follows.
Rainfall Pattern in Nigeria
The importance of the knowledge of rainfall pattern has necessitated many researchers to carryout studies on the subject. (Babatolu (2002) studied spatial distribution of rainfall in Ondo State, (Olaniran, 1990) investigated climate change in Nigeria, variation in rainfall receipt per rain-day and observed that there has been a progressive early retreat of rainfall over the whole country, and consistent with this pattern, reported a significant decline of rainfall frequency in September and October which, respectively coincide with the end of the rainy season in the northern and central parts of the country. Chukwukere (2005) carried out a research on monthly rainfall at Isunjaba Imo State from (2000-2004), he revealed that there exists a trend for the period considered and it showed a regular cyclical movement. Climate variability has been noted to arise as a result of changing rainfall pattern, some regions have experienced marked decline in rainfall patterns depending on the location. For state whose economy largely depends on efficient and productive rain-fed agriculture, rainfall patterns and trends are often quoted as one of the major causes of several socio-economic problems like food insecurity in the state (Ekwe et al, 2014).
Study by Enete and Ebenebe (2009) showed that the trend suggested a general decline in rainfall values in recent times. Rainfall values for the years under study suggested values between 265.37mm and 320.21mm. This supports the findings of Olaniran & Summer (1989, 1990) in their study; they found that there was a progressive early decline of rainfall over the country. Following the pattern, they reported a noticeable and significant decline of rainfall frequency in September and October which coincide with the end of rainy season in almost every parts of the country especially in the Northern and Central parts of Nigeria.
Rainfall
Rain is liquid water in the form of droplets that have condensed from atmospheric water vapor and then become heavy enough to fall under gravity. Rain is a major component of the water cycle and is responsible for depositing most of the fresh water on the Earth.
The major cause of rain production is moisture moving along three-dimensional zones of temperature and moisture contrasts known as weather fronts. If enough moisture and upward motion is present, precipitation falls from convective clouds (those with strong upward vertical motion) such as cumulonimbus (thunder clouds) which can organize into narrow rainbands. In mountainous areas, heavy precipitation is possible where upslope flow is maximized within windward sides of the terrain at elevation which forces moist air to condense and fall out as rainfall along the sides of mountains. On the leeward side of mountains, desert climates can exist due to the dry air caused by downslope flow which causes heating and drying of the air mass. The movement of the monsoon trough, or intertropical convergence zone, brings rainy seasons to savannah climes.
The urban heat island effect leads to increased rainfall, both in amounts and intensity, downwind of cities. Global warming is also causing changes in the precipitation pattern globally, including wetter conditions across eastern North America and drier conditions in the tropics. Antarctica is the driest continent. The globally averaged annual precipitation over land is 715 mm (28.1 in), but over the whole Earth it is much higher at 990 mm (39 in).
CHAPTER THREE
METHODOLOGY
Study Area
The study area is Calabar Meteorological Centre Calabar.
Calabar is the capital of Cross River State, Nigeria. It was originally named Akwa Akpa, in Efik language (Afigbo, 1987). The city is adjacent to the Calabar and Great Kwa rivers and creeks of the Cross River (from its inland delta).
Calabar is often described as the tourism capital of Nigeria, especially due to several initiatives implemented during the administration of Donald Duke (1999–2007), which made the city the cleanest and environmentally friendliest city in Nigeria (Achum, 2017). Administratively, the city is divided into Calabar Municipal and Calabar South Local Government Areas. It has an area of 406 square kilometres (157 sq mi) and a population of 371,022 as at 2006 census.
On 10 September 1884, Queen Victoria signed a Treaty of Protection with the King and Chiefs of Akwa Akpa, known to Europeans as Old Calabar. This enabled the United Kingdom to exercise control over the entire territory around Calabar, including Bakassi.
Today, Calabar is a large metropolis with several towns like Akim, Ikot Ansa, Ikot Ishie, Kasuk, Duke Town, Henshaw Town, Cobham Town, Ikot Omin, Obutong.
CHAPTER FOUR
DATA PRESENTATION AND INTERPRETATION OF RESULTS
Data Presentation
Table 1 shows the monthly mean rainfall values for the years 2002 – 2014. While Table 2 shows monthly mean rainfall amounts for June, July, August and September extracted from Table 1 and from which dry spell days are plotted. Table 3 illustrates the computed rainfall deviation and anomalies within the years under consideration 2002 – 2014.
CHAPTER FIVE
CONCLUSION AND RECOMMENDATIONS
Introduction
This chapter presents the conclusion and recommendations for further studies.
Conclusion
This present study has enabled us to understand the temporal variations in daily, annual, monthly and seasonal rainfall amounts over Nigerian Meteorological Center Calabar. The driest and the wettest year and month in Nigerian Meteorological Center Calabar for the period of study has been identified and the sequence documented for future reference on the probability of droughts and floods. The study revealed a significantly high value of mean annual rainfall over. Nigerian Meteorological Center Calabar within the period of study (2002 – 2014) of 4687.59 mm which is good for agriculture and water resource planning.
The study also showed a decline in trend pattern of mean annual rainfall over the study area for the period of study and significant daily variations for the months under consideration when analyzed in Julian days. The anomalous departures from the mean were observed to be very small with the highest positive departure from the mean of approximately 11% in 2006. This seems to support early research that the Little Dry Season decreases in intensity towards the southeast and hence is considered merely a rainfall occurrence minimum in-stead of a true “Little Dry Season”.
Recommendation
Timely observations and forecasts of rainfall onset, duration (length of rainy season) and cessation are useful in addressing the persistent problem of dwindling water resources. This study, therefore recommend an integrated water-resources management as well as sustainable agriculture especially during the ‘little dry season’.
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