Environmental constraints on the interdependence of drainage basin morphometric properties in the upper Cross River.

Abstract

This study seeks to identify the effects of environmental heterogeneity on the interdependence of drainage basin morphometric properties and its implications for applied studies-particularly flood abatement/control. A detailed morphometric analysis of 22 3rd – order streams in the upper Cross River basin was carried out. At least six 3rd order streams were chosen from diverse geologic formations- Precambrian Basement Complex rocks and Asu River Formation in Abakaliki and Ikom-Mamfe Formation. The thirteen measured/derived data on the morphometric parameters were tested for normality and logarithm transformation was carried out. The SPSS soft ware was employed to generate a correlation matrix using the transformed data set. The transformed data matrix was also subjected to principal component analysis. The principal components having eigen-values greater than 1.0 were rotated using the varimax method in order to produce an orthogonal transformation of the components and simplify interpretation. The results indicate that the degree of inter-correlations among the thirteen morphometric variables is weak. Only 32.1% of the 78 possible relationships were significant at 0.05 level. We do know that an increase in the interdependence of the morphometric properties of drainage basins is indicative of a lessening of environmental constraints [lithology] on the stochastic processes that generate stream networks. The result of Principal Component Analysis shows that the four factor model account for 83.90% of the variation in the original data. For example factor1[index of drainage dissection] explains36.55% of the variation in the data and is inversely related to basin size. The infrequent occurrence of flooding in the basin is caused by rain-swollen tributaries discharged into main channel at different periods.

KEYWORDS: Factor analysis, Lithology, Nigeria, Basement complex, Eigen Value, Morphometry