Land-Use and Land-Cover Analysis of Ilorin Emirate Between 1986 and 2006 Using Landsat Imageries
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African Journal of Environmental Science and Technology Vol. 6(4), pp. 189-198, April 2012 Available online at http://www.academicjournals.org/AJEST DOI: 10.5897/AJEST11.145 ISSN 1996-0786 ©2012 Academic Journals Full Length Research Paper Land-use and land-cover analysis of Ilorin Emirate between 1986 and 2006 using landsat imageries J. B. Olaleye 1, O. E. Abiodun 1* and R. O. Asonibare 2 1Department of Surveying and Geoinformatics, University of Lagos, Lagos State, Nigeria. 2Department of Surveying and Geoinformatics, Kwara State Polytechnic, Kwara State, Ilorin, Nigeria. Accepted 2 April, 2012 This paper examines changes in land-use and land-cover pattern in Ilorin Emirate in Nigeria between 1986 and 2006. Landsat images of Ilorin Emirates at three epochs (1986, 2000 and 2006) were used. An administrative map of local governments in Kwara State and a land-use map of Ilorin were used as base maps. Global Mapper Software was used for the image enhancement; image classification was done with environment for visualizing images (ENVI) software and was later exported to the ArcGIS for further processing and analysis. The land consumption rate and land absorption coefficient was determined to aid the quantitative assessment of change. Subsequently, an attempt was made at projecting the observed land-use / land-cover for a period of 14 years ending at 2020. The result of the work shows a gradual growth in built-up land between 1986 and 2000 and this tends to grow more rapidly between 2000 and 2006. It was also observed that the change by 2020 may likely follow the trend observed in 2000 and 2006. It is recommended that the information from the results of this work should be use to optimally and effectively plan and manage the study area. Key words: Land-use, land-cover, land consumption rate, land absorption coefficient, change detection. INTRODUCTION Background of study and estimate the impacts they may have on the environment. Land is the foundation of all forms of human activity, from In the simplest form, land-use is referred to the use in it we obtain the food we eat, the shelter we need, the which a piece of land is put to. It centres on the human space to work and the room to relax (Briassoulis, 2000). activities that relate to a particular parcel of land. The Land represents about 29% of the Earth’s surface. The magnitude of land-use change varies with the time use of land is known as land-use morphology, it varies interval being examined as well as with the geographical considerably from place to place. Metropolitan areas in area. Moreover, assessment of these changes depends Nigeria are growing at an unprecedented rate, creating on the source of the data used, the definitions of land-use extensive urban landscapes. Many of the farmlands, types, the spatial distribution, and the data sets used. wetland and savanna in Nigeria of 1960s have been Change detection is the process of identifying differences transformed during the past 50 years into human in the state of an object or phenomenon by observing it at settlements. The changes in Nigeria are pervasive, but different times (Singh, 1989). Change detection is an without a clear understanding of how the changes can be important process in monitoring and managing natural analyzed and their impacts known. It is not until a spatial resources and urban development because it provides and temporal study of these landscape transformations is quantitative analysis of the spatial distribution of the carried out that we can begin to appreciate the changes activities of interest. Macleod and Congation (1998) identified four aspects of land-use change detection that are important: (i) detecting the changes that have occurred (change / no-change), (ii) identifying the nature *Corresponding author. E-mail: [email protected]. of the change, (iii) measuring the areal extent of the 190 Afr. J. Environ. Sci. Technol. change and (iv) assessing the spatial pattern of the tripled in size between 1989 and 2009. In the study of change. Mundia and Aniya (2006) on land-use in Nairobi, they Population is a very important factor or agent of change cover the period between 1976 and 2000. They con- in land-use in an area. For instance, as population cluded that urban expansion has replaced agricultural increases, construction of dwellings increases, thus farmlands and other natural vegetation, thereby affecting engendering conversion of cropland and forest land to habitat quality and leading to serious environmental settlements. These urban land-uses are of various types degradation. In Nigeria, Barredo and Demicheli (2003) in which could be for industrial, commercial, government, as their study on urban sustainability issues in African well as transportation purposes. countries focussed on urban expansion in Lagos. They The underlying causes of land-use change could be described land-use simulation for the city of Lagos using broadly categorized into two: proximate (direct or local) an improved version of CA model prototype. The work and underlying (indirect or root) (Lambin et al., 2003). included a twenty-year simulation run until 2020. Also, The proximate causes of land-use change refer to how Adeniyi and Omojola (1999) carried out a study of land- and why local land-cover and ecosystem processes are use and land-cover change in Sokoto - Rima Basin of modified directly by humans. The underlying causes North - Western Nigeria between 1962 and 1986. The explain the factors responsible for these local actions. In work revealed that land-use and land-cover of the areas general, proximate causes are a local land-use which is was unchanged before dam construction while settlement as a result of land-use decisions made by individual land- alone covered most part of the area. However, during the owner or other entity that controls individual land. post - dam era, land-use/land-cover classes changed but Underlying causes originate from regional factors such as with settlement still remaining the largest. Barredo and government policy, regional/global economics. However, Demicheli (2003) note that “urban population and expan- it is the interaction of drivers at multiple scales which sion is increasing in developing countries particularly eventually leads to change in land-use. For instance, Africa. These immense urban agglomerations, which biophysical drivers of land-use change, such as, droughts often show a dramatic sprawl coupled with an explosive resulting from climate change or loss of soil fertility due to population growth, have social consequences and are erosion may be as important as human drivers, which disastrous to the environment”. include economics and policy. The interaction of these An attempt has been made to document the growth of biophysical drivers of change with cultural or social Ilorin and its environs in the past using Landsat imageries drivers of change could include deforestation, urbani- (Olorunfemi, 1983; Zubair, 2008). However, full coverage zation, desertification and afforestation. of the entire emirate has never been achieved. In the Information on land-use serves as a major input for any previous studies, maps and aerial photographs were program on energy conservation, for monitoring environ- processed using the traditional methods of maps and mental hazards and for the enhancement of equitable photo interpretation. In recent times, the multi- distribution of resources. Information on land-use change dimensional dynamics of landuse / land-cover particularly has also been found to be of great importance in the in settlement expansion, requires more powerful and political administration of many countries. Remote sophisticated spatial models and tools that geographic sensing and spatial analysis have been recognized and information system (GIS) and remote sensing provide. used as powerful and effective tools to monitor land-use Moreover, recent changes in global climate and its change. Satellite remote sensing collects multispectral, immense consequences requires that changes in land- multi-date and multi-spectrum data can be used to use / land-cover, which is one of the principal causes of construct broad-scale land-use data bases and provides climate change should be monitored on a regular basis in valuable information in under-standing and monitoring the every part of the world. process of land-use change. The aim of this study is to study the pattern of land-use /land-cover change in Ilorin emirate in the last 20 years Study area using multi-epoch data. It is intended to develop a probabilistic model of land-use change and predict likely Ilorin is the present day capital of Kwara State in the changes that would take place in the same area over the north central Region of the Federal Republic of Nigeria. It next period of 14 years. is a pre-dominantly Islamic City and presently inhabited Studies have been conducted on the land-use of by people of diverse culture. The Entire Ilorin community various cities in Africa. For instance, Wu et al. (2003) comprises of five Local Government Areas namely- Ilorin investigated the factors influencing urban land-use in West, Ilorin South, Ilorin East, Asa and Moro. These Nouakchott, Mauritania. They concluded that population Local Government Areas are all under one entity known growth is the only factor responsible for urban expansion as Ilorin Emirate. Ilorin emirate in Kwara state is as in Nouakchott. Tewolde and Cabral (2011) studied urban shown in Figure 1. The study area only covers 5.57% of sprawl and its impact on other land in Asmara, Eritrea. the state and it has 38% of the entire population of the The result of the study indicated that the built-up area has state. Olaleye et al. 191 462000 mE 862000 mE 1135000 mN 1135000 mN N N I NIGER STATE N E B F O C I L B U P E R LEGEND = Local Govt.