Journal of Environment and Earth Science www.iiste.org ISSN 2224-3216 (Paper) ISSN 2225-0948 (Online) Vol.5, No.2, 2015 32 Effect of Urban Growth on Urban Thermal Environment: A Case Study of Sekondi-Takoradi Metropolis of Ghana Bernard Kumi-Boateng 1 Eric Stemn 2* Eric A. Agyapong 3 1.Geomatic Engineering Department, University of Mines and Technology, P. O. Box 237, Tarkwa, Ghana 2.Environmental & Safety Engineering Department, University of Mines and Technology, P. O. Box 237, Tarkwa, Ghana 3.Environmental Science Department, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana *Email of corresponding author: estemn@umat.edu.gh Abstract The Sekondi-Takoradi Metropolis of Ghana has been experiencing fast urban growth over the past two decade. This urban growth has resulted in changes in the surface cover which consequently has cause remarkable urban thermal environmental problems. This research used two multi-temporal Landsat Thematic (TM) and Enhanced Thematic Mapper Plus (ETM+) images of the years 1991 and 2008 respectively to evaluate the effect of urban growth on land surface temperature (LST) using an integrated remote sensing and GIS approach. Several remote sensing techniques were used to carry out urban growth analysis. This assisted in determining the changes that have taken place over the 17 year period. The integrated use of remote sensing and GIS was subsequently employed to analyse the effect of urban growth on surface temperature. Local climate change was also studied using multi-decade temperature data. The results showed that urban development had increased surface radiant temperature in the study area by 4.3 ° C in the urban expanded areas. The results suggest that urban expansion has a certain effect on the monthly average surface temperature as well the seasonal average temperature changes of the Metropolis. Keywords: Land Surface Temperature, Urban Growth, Remote Sensing, Urban Heat Island, NDVI 1. Introduction During the last decades the world has undergone unprecedented urban growth and most of this growth has occurred in developing countries especially in Africa. These occurring urban growths have severely altered the biophysical environment. In terms of ecological impact, urban expansion has been identified as one of the most significant and long-lasting forms of land use and land cover change and its extent of increase is linked to population growth and economic development (Bounoua et al., 2009). Urban growth, both in population and in areal extent, transforms the landscape from natural cover types to increasingly impervious urban land. The result of this change can have significant effects on local weather and climate (Landsberg, 1981). By replacing the landscape with impervious materials such as asphalt, buildings, roads, parking lots, metals and other paved surfaces, urban areas usually have higher solar radiation absorption and a greater thermal conductivity and capacity such that heat is stored during the day and release at night. The removal of natural cover types and subsequent introduction of these urban impervious materials modify the energy balance of the earth surface, with a successive rise in surface temperature. This alteration of the land cover modifies the urban climate, causing it to be warmer than surrounding rural environment and is referred to as urban heat island (UHI) (Voogt et al., 2003). This increase in surface temperature in urban areas could potentially results in the development of meteorological events like modification of precipitation pattern, increase energy and air conditioning demands and raise pollution levels. The development of UHI can potentially contribute to global warming and affect the environmental quality and the long-term sustainable development of localities that continue to experience it. In the Sekondi-Takoradi Metropolis (SKM) of Ghana, land-use-land-cover (LULC) patterns have experienced changes due to accelerated economic development and population increase. Urban growth keeps on increasing and pressure on the environment is occurring. Massive natural land covers are disappearing, being converted to urban or associated uses. Land which was initially covered with vegetation is now being covered with reflective impervious structure such as road and building. These land cover modifications could therefore have diverse environmental and meteorological problem. There is therfore the need to evaluate the effect of urban growth both at local and regional scale. In the past, temperature changes (UHI) studies were carried out using traditional methods for isolated areas, and with in-situ measurements of ground meteorological data (air temperature) (Streutker, 2002; Weng, Lu , & Schubring, 2004). This traditional approach of using in-situ measure data even though considers the temporal resolution; its spatial resolution is limited. Satellite remote sensing has the ability to monitor changes in urban surface temperature on all scales, and subsequently provide qualitative physical data, present heterogeneous disturbed land surface characteristics. All of these can chiefly facilitate our understanding of urban and suburban environment and its relationship with urban growth.