Incidence of Land use Change on Flooding and River Bank Erosion in Ngoketunjia Division, North West Region, Cameroon

Abstract

Man in his unlimited quest for a good life through varied activities and land use changes have become an important geomorphic agent. Based on this assertion, this study was designed to examine the implications of land use changes on the incidence of flooding and river bank erosion in Ngoketunjia Division. The two-stage random sampling technique was used to administer questionnaires to 384 household heads who were predominantly farmers and occupants of flood prone areas. High resolution Landsat images of 1980 and 2016 were vectored, treated, and analysed in ArcGIS and used in conjunction with Google Earth images to delimit the bank line of a segment of the Noun River. The Pearson Correlation Coefficient (r) and the Spearman Rank Correlation coefficient (rho) were used to test the hypothesis of the study at 95% confident level. A significant positive correlation was found between the incidence of flooding and agricultural land use as well as between the incidence of flooding and settlement. The coefficients of determination (R2) of both correlation analyses revealed that agricultural land use contributed 60% of variability in the incidence of flooding while settlement shared 39.6% in the variability of its rank. An association was also noticed between some land uses and river bank processes. Mass movement and bank undercutting were found to be most dominant in cultivated areas and least in woodland areas. Geospatial analysis further revealed that between 1980 and 2016, a surface area of 2763m2 was eroded by the Upper Noun River within the approximately 4.59Km long segment delimited for the study as the gallery forest and wetlands of the area gradually gave way to farmlands and settlements. This gives an annual bank erosion rate of 76.75m2 within the segment during the 36 years’ period. The study recommends effective structural approaches to river bank stabilization, deepening and straightening of river channels while checking excessive upland degradation to reduce accelerated surface and river bank erosion.