AN ASSESSMENT OF THE EFFECTS OF URBAN GEOMETRY ON SPATIO- TEMPORAL VARIATION OF AIR TEMPERATURE IN KADUNA METROPOLIS, KADUNA STATE, NIGERIA.

Usman, S. U *, Abdulhamed, I. A Iguisi, E.O. and Sawa, B A

This study investigates the effect of urban geometry on intra-urban air temperature variation in Kaduna metropolis. This is done by classifying the urban environment according to local climate zone (LCZ) system of classification. Urban geometry was determined as sky view factor (SVF), computed from digital sky view photographs taken with fish-eye lens, using BMSky View program. Temperature data were collected using temperature dataloggers (thermochron ibuttons). Results show that SVF has a range of 0.514 in the study area, higher intra-urban temperature range (4.37^oC) at night, medium range (2.71^oC) in the afternoon and low range (1.84^oC) in the morning. Linear regression of temperature on SVF on hourly basis yielded coefficients of regression (r) and determination (r²) values which are high during evening and first-half of the night hours and low during late night to noon hours. Higher student’s t test values also indicated more significant relationship between the two parameters from late evening to mid-night and less significant relationship from late night to early evening. This indicates that urban geometry exerts more influence on urban air temperature at late evening and night times. It is recommended that in planning cities here in the tropics, storey buildings should not be closely located to avoid reducing SVF, there should be open spaces between buildings to allow for urban ventilation and green areas should be provided for their cooling effects.

Key words: Canyon Geometry Effect, Sky View Factor, Spatio-temporal, Urban Geometry.