TREE CANOPY COVER VARIATION EFFECTS ON URBAN HEAT ISLAND IN ENUGU CITY, NIGERIA

Abstract

Urban settings, such as buildings of varying heights, large Ares of paved streets and parking lots generate a unique urban weather environment, such as urban heat Islands. In addition, high temperature and heat waves are becoming more frequent in our cities. Rising temperatures are being blamed on global warming and rapid urbanization. Street trees are highly effective at ameliorating urban warmth at the micro-scale. This study seeks to determine the contributions of street trees in Enugu Urban in ameliorating urban heat Island. Measurements and Monitoring of temperature under street trees in some selected areas were undertaken. Data collection spanned over two seasons (dry and rainy seasons) represented by months of February - March and June- July respectively. A control temperature monitoring data was generated in some selected streets without trees. The resultant data were subjected to further data analysis in order to assess the thermal comfort benefits of street trees using Tzenkova discomfort Index. The result indicated that street trees decreased street temperatures by 8 and 5 degree Celsius during rainy and dry seasons respectively. The result also showed that trees like anacarduim, catalpa Bungei, mangifera Indica and azadirachta indica can reduce ambient air temperature to as low as 12 degrees Celsius. In addition, the result pointed out that where street trees are planted, human thermal comfort (HTC) are usually tolerable. In  conclusion the Decreasing temperature using shade trees have other multiplier effects such as lowering evaporative emissions of volatile organic compounds (VOC) from cars, reduction of urban noise, increase property values, decrease stress and aggressive behavior.

Keywords: Urbanization, Street trees canopy cover, urban heat Island, temperature variation