MORPHOLOGICAL RESPONSE OF RIVER NGADDA TO URBANIZATION IN MAIDUGURI METROPOLIS, NIGERIA

Abstract

This study examines the River Ngadda channel morphology response to urbanization in Maiduguri Metropolis, Northeastern Nigeria. Sample sites were selected in a basin with different levels of urbanization. Field measurements of channel full dimension and reach dimension parameters were assessed in the three segments of the basin. Data on the channel morphological variables were collected through field measurement of the cross sectional area characteristics of the river from where the longitudinal characteristics were defined. 15 sample sites were established along 22.9km stretch of the river channel. Five sites each in urban, semi urban and rural segments respectively were selected. The results shows all the six parameters of full channel dimension shows that the urban segment is larger than the semi-urban and rural segments. The result also shows that the width and depth parameters increase in the downstream direction in the urban and semi urban segments, while cross sectional area and wetted perimeter increases in the rural segment. Analysis of variance for the comparison of the regression lines in the three segments revealed that variations occurred in all the six parameters downstream for all the channel form variables indicated that there are variations. The result further provide F ratio which implies the extent of variation showed that the bed slope F ratio 37.18 and wetted perimeter F ratio 28.14 were the most variables downstream among the morphologic parameters considered followed by channel depth 14.01, channel 13.09 and width to depth ratio 10.25. While the cross-sectional area is the least variable with an F ratio of 6.72. The bed slope with F ratio as high as 37.57 is the most widely varied downstream, less variations occur in cross sectional area downstream with F ratio of 6.72. However, bed slope reflected a statistical insignificant difference at 0.05 α-level with p-value of 4.28. While all other parameters varying downstream (e.g., width, depth, wetted perimeter, cross sectional area and width to depth ratio) exhibited significant difference at 0.05 α-level.