ASSESSING REMOTELY SENSED TEMPERATURE HUMIDITY INDEX AS HUMAN COMFORT INDICATOR RELATIVE TO LANDUSE LANDCOVER CHANGE IN ABUJA, NIGERIA

Abstract

Abuja, Nigeria’s capital city has witnessed remarkable expansion, growth and developmental activities such as building, road construction, deforestation and many other anthropogenic activities since its inception in 1976. One of the factors that is inevitably altered by this increasing land surface modification and alterations which is highly relevantto human well-being is thermal comfort. It is therefore pertinent to study the thermal environment of the city if Abuja will avoid the associated problems of growing and expanding city like many others in the world. Thus this study examines the use of Remote Sensing (RS) and Geographic Information System (GIS) in mapping Temperature Humidity Index(THI) as human comfort indicator relative to Land Use Land Cover Change (LULCC) in Abuja using Landsat TM and ETM+ data of 1987, 1999, 2009 and 2014. This is to detect changes that has taken place in this status between these periods. The results data of 1987, 1999, 2009 and 2014. This is to detect changes that has taken place in this status between these periods. The results(discomfort) while the periods between 1999 and 2009 show a remarkable improvement in GOS with an attendant increase in region with THI values between 19-26 where comfortable condition is achieved. An attempt was made at comparing differences in the THI between five different land cover classes: water body, built-up area, closed canopy vegetation, open vegetation and waste land. With the exception of water body and closed canopy vegetation, hot and dry (discomfort) comfort index class category is the most dominant across most of the land cover classes. This order of dominance is the highest in wasteland and built-up areas land cover categories. Furthermore, an attempt was also made at linking outdoor thermal bioclimatic condition with urban space designing and landscape architecture. In achieving this, comparisons were drawn between the spatial variation of THI over Abuja metropolis and the adjoining residential Karu suburb. It was observed that Abuja metropolis was slightly bioclimatically better than Karu. This is attributable to the presence of green spaces and water features within the landscape of the Abuja metropolis as opposed to that of Karu which is purely a residential area usually made up of asphalt concrete (impervious materials) likely to be warmer and thus radiate heat which can worsen thermal comfort conditions during the day. The results presented in thisresearch show that beyond their aesthetic role and pleasant nature perception, increasing green spaces and presence of water features in cities represents a significant mitigation technique as it participates in heat- stress relaxation and outdoor thermal comfort enhancement.