Determination of Urban Spatial Expansion of Thika Municipality Using Land Use/Cover Change and Shannon’s Entropy

Abstract

Spatial urban expansion forms an integral part of urban planning. This study assesses spatial expansion of Thika Municipality, in terms of land use/cover (LUC) change and Shannon’s entropy over a period of 34 years. Thika Municipality is one of the fastest growing industrial and socio-economic towns in Kenya. It is characterized by rapid and less dense urban growth evidenced by unplanned incremental urban development. Remote sensing and GIS techniques were used to determine urban expansion. Landsat images acquired in 1976, 1988, 2000 and 2010 were classified to determine LUC change and Relative Shannon’s Entropy. The study found significant changes in land use/cover in Thika Municipality. With built-up area expanding at a rate of 0.91% (of the total area) per year, which translates into urban expansion of +31% in 34 years, bare-land expanded at 0.21% per year (+7% in 34 years), while agricultural/vegetation decreased at 1.12% per year (-38% in 34 years). No urban sprawl was detected in 1976. However, instances of urban sprawl were observed from 1988 to 2010, in an incremental manner.