EXAMINATION OF LULC OVER NIGERIA BETWEEN 1991 AND 2016
ABSTRACT
Remote sensing is used in this research work for the development and acquisition of Land use/land cover data, pattern and its attendant effects in Warri metropolis, Delta State Nigeria. Remote sensing images and digital data verified by ground trothing (field work) satellite data are used to assess the rate of change in Land use / Land cover between 1991 and 2016. Remote sensing and geographic Information System (GIS) help integrate natural, cultural, social and economic information to create spatial information system on the available terrain resources. Sets of United states geological society (USGS) images were acquired corresponding with the years, field checked to ascertain the data captured on the terrain. The digital satellite data are incorporated as input data into ArcGIS software to separately map out the land use/land cover units and their magnitude determine. Three distinct units were identified in classification of land use/landed cover pattern categories as follows: Built-up areas, vegetation and Water bodies. Ground truthing was carried out to ascertain the accuracy of data and there are major changes in the land use/land cover. It was discovered that there are rapid inbuilt-up areas evidently explained in buildings projects that resulted in decrease in forest land, agricultural land and open space. This is attributed to the anthropogenic activities of farming, bush burning, grazing, etc. However, the area occupied by water remained unchanged over the years. This study demonstrates that remotely sensed data and GIS based approach is found to be timely and cost effective than the conventional method of analysis, classification of land use pattern effective for planning and management.
CHAPTER ONE INTRODUCTION 1.1 Background of the study
Land is a specific area of the earth surface with physical entity in terms of its topography and spatial nature (Ashaye, 1987), and one of the characteristic of space that is widely recognized as significant for planning and management purposes (Anderson, Hardy, Roach and Witmer, 1976). Land is therefore, a key element for any developmental processes that takes place on the earth surface but land in urban areas suffers unique ecological and economic pressures (Drescher, 2000), leading to a lost in its land based. Land is the most important natural resources on which all activities are based.
Land cover (LC) according to Campbell (1996), refers to the physical cover of the earth including natural vegetation, crops, artificial constructions that cover the land surface On the other hand, land use (LU) refers to the actual use of the land which is the purpose for which man exploits the land cover (Omojola, 1997); land use describes the use of the land by the people usually with emphasis on the functional role of land on economic activities (Campbell, 1996): and man‘s activities which are directly related to the land (Anderson, Hardy, Roach and Witmer, 1976). Therefore, Land use and land cover (LULC) are treated jointly. They represent both the physical cover and the human imprints on land. Therefore, Land use-land cover (LULC) is among the most important phenomenon of the earth‘s land surface (Lambin and Geist, 2001).
The land use/ land cover pattern of a region is an outcome of natural and socio – economic factors and their utilization by man in time and space. Land is becoming a scarce resource due to immense agricultural and demographic pressure. Hence, information on land use / land cover and possibilities for their optimal use is essential for the selection, planning and implementation of land use schemes to meet the increasing demands for basic human needs and welfare.
As population increases, there is a corresponding increase in human alteration or modification due to increase in the diversity of functional activities (Ariyo, 1991). Man continued to temper with the original land cover and convert it into other land uses in order to meet his immediate needs. Where the supply of serviced land cannot meet his demand, the tendency is often the indiscriminate conversion of other land uses such as those meant for agriculture land, vegetation land, crop land, forest land, bare lands, environmental protection etc to uses that are at variance with the conceptual plans of such towns and cities (Ariyo, 1991). Globally, land cover today is altered principally by direct human use: agriculture and livestock raising, forest harvesting and management, and urban and suburban construction and development. Hardly can we find any vegetation that has not been affected by man in the world. About 400,000 hectares of vegetation cover has been confirmed to be lost annually (Adesina et al., 1999). Due to anthropogenic activities, the earth surface is being significantly altered in some manner and man’s presence on earth and his use of land has had a profound effect on rather all meteorological/climate parameters. Land transformation has been asserted to be one of the most important fields of human induced environmental transformation (Fasal, 2000). Environmental protection has faced critical problems due to several factors ranging from increasing population, demolishing of natural resources, environmental pollution, unplanned land use and several others. Several research works, has shown that unplanned changes of land use due to urbanization have become a major problem (Zhao, 2003; Nanda, 2005). Most land use changes occur without a clear and logical planning and without attention to their environmental impacts. Major flooding, air pollution in large cities as well as deforestation, urban growth, soil erosion, desertification, are all consequences of a mismanaged planning without considering environmental impacts of development planes. The rapid land use changes by the growing population have reduced natural vegetation cover and resources in most countries of the world (Nicholson, 1987).
Therefore, the activities of man are the most driven force for land use and land cover changes of any town or city.
As a result, information on the rate and kind of changes in the use of land resources is essential for proper planning, management and to regularize the use of such important resources. Knowledge about existing land use and land cover and its trend of change is essential for various reasons. Land use data are needed in the analysis of environmental processes and problems that must be understood if living conditions and standard are to be improved or maintained at current levels. Changes in land use can be due to urban expansion, loss of agricultural land, changes in river regimes, the effect of shifting cultivation, the spread of erosion and desertification and so on. Therefore, this requires not only the identification of features but also the comparison of subsequent data in order to recognize when valid changes has taken place.
The use of satellite remote sensing techniques and geographic information systems (GIS) for the identification, mapping and analyses of land use and land cover changes have gained prominence in recent years as high resolution satellite data have become more readily available.
Remote Sensing (RS) and Geographic Information System (GIS) are now providing new tools for advanced ecosystem management. The collection of remotely sensed data facilitates the synoptic analyses of Earth - system function, patterning, and change at local, regional and global scales over time; such data also provide an important link between intensive, localized ecological research and regional, national and international conservation and management of biological diversity (Wilkie and Finn, 1996).
1.2 Statement of the problem
Land use and land cover changes are evident in Nigerian cities as with other developing nations of the world. Being one of the most urbanized Countries on the African continent with estimated urbanization rate of 3.5% annually, Nigeria has witnessed a tremendous urban expansion over the years (World Bank, 2009). Oyinloye (2016) asserted that the share of urban population out of the total population of Nigeria was less than 7% in 1931 but has continued to escalate over the years from about 10% in 1952 to 19.2% in 1991 to 48% in 2010 and it reached 50% in 2012. The above increase in urbanization rate indicated that by the year 2012, half of the population of Nigeria were already living in urban areas. This explosive increased in population has resulted in rapid human alteration or modifications of the biosphere that brought changes in the land use and land cover distribution of all Nigerian cities with Warri metropolis in Delta state not an exception.
However, Land use and land cover changes have far reaching consequences. Therefore, a modern nation, as a modern business, must have adequate information on many complex interrelated aspects of its activities in order to make decisions. Land use is only one such aspect, but knowledge about land use and land cover has become increasingly important if the Nation plans to overcome the problems of haphazard, uncontrolled development, deteriorating environmental quality, loss of prime agricultural lands, destruction of important wetlands, and loss of fish and wildlife habitat. Land use data are therefore needed in the analysis of environmental processes and problems that must be understood if living conditions and standards are to be improved or maintained at current levels.
Warri in Delta state has witnessed remarkable expansion, growth and developmental activities such as building, road construction, deforestation and many other anthropogenic activities since its inception just like many other cities in Nigeria. This has therefore resulted in increased land consumption and a modification and alterations in the status of her land use land cover over time without any detailed and comprehensive attempt (as provided by a Remote Sensing data and GIS) to evaluate this status as it changes over time with a view to detecting the land consumption rate and also make attempt to predict same and the possible changes that may occur in this status so that planners can have a basic tool for planning. It is therefore necessary for a study such as this to be carried out if Warri city will avoid the associated problems of a growing and expanding city like many others in the world.
1.3 Justification of the study
The earth's surface is changing as a result of natural phenomena or human activity, for example, wildfires, lightning strikes, storms, pests, agro-forestry, agricultural expansion, social, economic, technological, historical factors and urban growth and the likes (Borak, Lambin & Strahler, 2000). Population growth is responsible for most of the changes in land uses due to diversity in functional activities.
In recent times, the dynamics of Land use Land cover and particularly settlement expansion in the area requires a more powerful and sophisticated system such as GIS and Remote Sensing data which provides a general extensive synoptic coverage of large areas than aerial photography.
Due to negative consequences of land use and land cover change, during the past decades, several international interdisciplinary research projects have been initiated on these issues including the International Geosphere-Biosphere Programme Committee on Global Change (IGBP, 1988) and the Land Use and Cover Change program (Messerli, 1997). Both of these projects indicated the need to construct an updated and accurate database concerning these changes, their meaning, their pace and the explanatory factors prompting their appearance (Mather, 1999). The ability to recognize that change is a key requirement for the accurate analysis of LULCC (Lambin, Baulies, Bockstael, Fischer, Krug, Leemans, Moran, Rindfuss, Sato, Skole and Vogel, 1999) instead of an improvement in the spatial resolution of image data and a detailed ground survey.
1.4 Aim and objectives of the research
1.4.1 AIM:
The aim of this project is to use remotely sensed data and GIS techniques to detect and monitor land use and land cover changes at different epochs preferably over 25 years (1991-2016) over Warri metropolis as our case study area.
1.4.2 OBJECTIVES:
The following specific objectives are addressed in our research in order to achieve our aim of study.
To determine land use/ land cover types of the study area at different epochs of 1991, 2002 and 2016. To capture the geospatial data within the study area using LANDSAT imagery of 1991, 2002 and 2016. To prepare land use map of the study area. To determine the trend, rate, magnitude and percentage of change of the various land use and land cover types. To predict future pattern of land use and land cover of the study area from 2016 to 2026. To provide recommendations arising from the study.
1.5 Scope of study
The study seeks to map and establish whether there have been changes in the land use of the study area of Warri metropolis.
1.6 Definition of terms
(i) Remote sensing:
Can be defined as any process whereby information is gathered about an object, area or phenomenon without being in contact with it. Given this rather general definition, the term has come to be associated more specifically with the gauging of interactions between earth surface materials and electromagnetic energy. (Idrisi 32 guide to GIS and Image processing, volume 1).
(ii) Geographic Information system:
A computer assisted system for the acquisition, storage, analysis and display of geographic data (Idrisi 32 guide to GIS and Image processing, volume 1).
(iii) Land use:
This is the manner in which human beings employ the land and its resources.
(iv) Land cover:
Describes the physical or natural state of the Earth’s surface.
(v) Ground Control points
Ground Control Point can be defined as a point on the earth surface with known location (i.e. fixed within an established co-ordinate system) which is used to geo-reference image data sources, such as remotely sensed images or scanned maps.
(vi) Geo-referencing
It is the process of establishing the correct position of an aerial photograph within a map or finding the geographical coordinates of a place name or street address.
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