MORPHOMETRY OF RIVERS AND LAND USE IN SABAH

Abstract

Rivers have traditionally been classified into three stages - youthful, mature and the old age stage. Each of these stages have their own characteristics that are distinct. For example, in the youthful stage the river has a V-shaped valley and steep sides. The mature stage has a wider valley and gentler slopes. In the old age stage, the river valley becomes U-shaped and the slopes become flatter. This classification has been applied to rivers in the temperate regions. The division of a river into three stages has now tested on rivers in the tropics. This study aims to prove that the division of the river into different stages is applicable to the rivers in Sabah. Rivers are divided into the various stages through its longitudinal profile. This longitudinal profile of the river is a graph of the gradient of the river from its source to the mouth. The youthful stage is thus typically near the source while the old age stage is near the mouth. In addition, it has been postulated that rivers would try to achieve a graded profile, which is one that depicts a smooth curve. This view began with W.M. Davis and has been popular until the 1950s. There are many factors that would affect the morphometry of a river basin and in turn this would affect the longitudinal profile and the cross sectional profiles. One of the factors is the land use pattern within the drainage basin. However, it is also found that the land use of the area also affects the morphometry of the river basin. Therefore the relationship between the two is intrinsically connected. It is also worthy to note that other factors do influence the land uses of the area and not just the morphometry of river. These factors include sociological, economic and political considerations.