ABSTRACT
All landsurfaces are composed of drainage basins which are the units of the land surface which collect, concentrate and promote the movement of water and sediment (Figure 2.1). The drainage basin is the unit which is basic to the transmission of energy from climate through geomorphological processes to give morphological results or landforms. Although the drainage basin can be visualized as a unit of study in ice-covered areas or in . Headwater Area of Tributary of River Exe, Devon
Snow covers the interfluve areas and the slopes of many of the valley sides are snow-free. Fluvial characteristics of such drainage basins may be investigated employing one of several approaches (Figure 2.2), and the process operating on several types of slope element can also provide focus for study. Maximum slope angles of this type of area have been investigated in relation to character of the subsurface material (p. 77) and, in addition to an expanding drainage network, subsurface stormflow (p. 56) contributes to the generation of stream hydrographs
https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9780429051807/eb7ef915-9c09-48d5-bf89-b402b4697494/content/fig2_2_1.jpg"/> 45deserts it is most useful where weathering, mass movement and water flow provide the basis of landscape morphogenesis. It is difficult to establish when the significance of the basin was first appreciated. This depended upon the realization that water from precipitation generates streamflow and Pierre Perrault in 1674 had measured rainfall over the Seine basin in France and had shown that as the river flow of the Seine was only one sixth of the rainfall amount then precipitation was ample to sustain river flow. This deduction therefore produced the concept of the basin as an area of the land within which precipitation could generate streamflow.