Urban sprawl may be defined as the scattering of new development on isolated tracts, separated from other areas by vacant land (Lata, et al. 2001). It has also been described as leapfrog development (Jothimani, 1977; Torrens and Albert, 2000). The need for monitoring urban development has become imperative to help curb the problems of this type of growth.
Monitoring urban development is mainly to find the type, amount and the location of land conversion for future planning (Shekhar, 2001). Urban sprawl varies in degrees between the developed and the developing world and subsequently they have differing consequences.
In a developing country such as Nigeria, development in urban areas and miscellaneous landuse types are isolated in the fringe areas followed by gradual filling of intervening spaces with similar uses, this is mainly due to rapid growth in population size which is usually uncontrolled.
The rapid rate of urbanization being experienced in Lokoja, Kogi State Nigeria, has created serious environmental problems noticeable along the Lokoja metropolis there is the unguided and uncontrolled expansion without due consideration to interrelated factors such as transport, employment, health and other livable factors. The city is experiencing expansion in all directions resulting in large scale urban sprawl and changes in urban landuse. This is noticed in the on the city fringes, this have increase the built up area and changes in land use patterns which had led to loss in valuable agricultural lands, natural forest cover and anthropogenic encroachment on fadama areas, and loss of surface water bodies and biodiversity .There is therefore a need to monitor such changes and to understand the processes, so as to be able to measure and plan so as to direct growth for healthy development.
2. Pattern of Sprawl in Lokoja
The fringe areas of the town of the Lokoja area, Felele, Ganaja area characterized by Random, sporadic and fragmented urban growth which had hindered development towards optimum units in the promotion of local public utility and services. Discontinuous urban growth is also posing the problem of land speculation.
Studies have shown that in areas of sprawl, of the study areas, like Lokongoma only 22% is connected to National Electricity Power Supply, subsequently 7% for Ganaja area and 7.1% for Otokiti area (Alabi and Ufuah, 2007).
The direction of expansion has been observed to tend towards the Okene-Kabba road and the Lokoja-Ajaokuta roads in a ribbon spread pattern. Land adjacent to these roads is developed but those without direct access remain in the rural uses/covers. The city is experiencing 'leapfrog' development due to lack of proper planning.
Remote sensing has been used to monitor this urban development, similar research have been carried out elsewhere by Howarth (1986), Fung and LeDew (1987), Li and Yeh (1998) and various techniques have been developed for land growth detection efficiency, including image differencing (Toll et al, 1980), Image rationing (Nelson, 1983), Masking Method (Pilon et al, 1988) and principal component analysis (Fung and LeDew, 1987; Li and Yeh, 1998).
3. Aim and Objective of Study
The aim of this research is to study the pattern and measure sprawl, this is to be carried out by using the Entropy (E) Method, which is based on two location factors, distances from the town centre and distance from roads to show and capture spatial pattern of sprawl.
4. Study Area
The study area, Lokoja lies between latitudes 7[degrees]45'N and longitude 6[degrees]45'E. Lokoja is the administrative headquarters of Kogi State in Nigeria. It is well connected and accessible through state and federal highways. It is also located close to confluence of the River Niger and Benue; the area is sandwiched between a water body and a hill i.e. River Niger and Mount Patti respectively which had streamlined the settlement to a linear one and has a modifying effect on the climate. …