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ANALYSIS OF LANDCOVER AND LANDUSE CHANGES IN ABA URBAN AREA USING MEDIUM RESOLUTION SATELLITE IMAGERIES

ABSTRACT

This study focused on the analysis of landuse and landcover changes in Aba Urban Area using medium resolution satellite imageries (Landsat ETM+, 2000 and Nigeria Sat-1, 2005) acquired for Aba Township in order to detect the changes that have taken place within this time interval. Change detection being a process of identifying differences in the state of an object or phenomena by observing it at different times. In determining the landuse/cover of Aba, Remote Sensing technique was applied using the ILWIS software in image processing and analysis.

The Landuse map of the study area was produced using ArcGIS/ArcView software. Two multidate datasets (LandsatETM+ image of 2000 and NigeriaSat-1 image of 2005) respectively and analogue base map Aba township (produced in 1991) were used. The base map was scanned, digitized and georeferenced in AutoCAD environment. The digitized base map was polygonized and classified. The Landsat ETM+ and the NigeriaSat-1 imageries were resampled to one resolution and classified. Through an overlay operation the various spectral and temporal changes in Landuses were obtained and analyzed. The result reveals that from 1991, 2000 to 2005, the River increased from 15.1% to 22.1% and finally to 22.4% due partly to increasing activities within and around the waterways, Builtup area increased from 21.7% to 26.8% and to 36.5%. Unlike river and built-up area, there is a significant disparity and trend in vegetation Landcover due to rapid urbanization and socio-economic activities. Thus, vegetal cover decreased from 63.2% in 1991 to 51.1% in 2000 and in 2005 it further decreased to 41.1% However, I recommended to Government that timely Landuse and Landcover mapping of the entire Aba Township should be embarked upon to forestall the ugly consequences of erratic and haphazard land utilization in the town. It was also recommended that the government and relevant authorities to embark on conversion of analogue maps of the state at different scales to digital maps and also update them to reflect the changes and development in the state. This will facilitate necessary landuse planning and forestall the rising sprawl in urban landuse in Aba Township.

 

 

CHAPTER ONE

1.0 INTRODUCTION

1.1 BACKGROUND OF THE STUDY

Research has proved that problems associated with environmental monitoring and

control persists through the history of mankind. But the situation is aggravated in

recent times due to man’s increasing intervention on the environment. There

remain few landscapes on the earth’s surface that have not been significantly

altered by human beings in some ways (Opeyemi, 2007).

Riebsame et al. (1994) observed that due to anthropogenic factors, the landscape is

significantly altered in some ways and man’s activities on the earth surface and his

cultural activities have produced a great influence upon the natural environment

resulting in an observable trends or patterns over a time scale. These changes in

Landuse and Landcover due to mankind’s contributions are pervasive and have

adverse implications on local, regional and global scales. Thus, according to

Igbokwe (2008) and Onu (2008), large scale transformation is commonly witnesses

in and around major cities of Nigeria.

Meyer (1995) observed that humans have an increasingly large role in the

modification of the global environment. In addition, Raddison et al. (1999) cited in

Igbokwe (2008) and Onu (2008) stated that population growth pressure forces man

to invade the undeveloped environment, hence, tampering with the Landscape and

disturbing the natural habitat.

Demographic and socio-economic factors have had increasing pressure on the

landscape as demands for food, water; shelter and fuel have increased regionally

and globally. Thus, Landuse practices are influenced by different environmental

conditions, political, climate, and demographic and social conditions.

Landcover refers to the natural surface of the earth undisturbed by human

activities. It is often used to represent vegetation, natural or man-made features and

every other visible evidence of Landuse e.g. forest, cultivated/uncultivated land,

settlements, etc. Landuse on the other hand, refers to the use of land by humans. It

is the alterations done to Landcover by human activities e.g. farming, road

construction etc. Landuse and Landcover change studies has become a key

component for managing of natural resources and monitoring environmental

changes. If we are going to manage our urban areas as systems for the betterment

of the environment, Igbokwe (2008) recommended that in Nigeria we need to gain

better understanding of the type of disturbances and changes that can occur in

urban systems. Igbokwe (2008) further stressed that landcover and landuse

information should form part of the environmental data, which are kept in the form ...Get Complete Material.


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