The Channel head

The overall appearance of a fluvial landscape is controlled by the density and structure of the valley network which drains water and sediment from the land. The channel network and the valley network are rarely equivalent. Instead, the channel head characteristically lies tens to hundreds of meters down-valley of the drainage divide (Figure 7.1 and 7.2). Consequently, the lincscale topography of many hillslopes is dominated by a network of unchanneled valleys which drain directly to the channel network or to a swale upslope of the channel head, i.e. the sourcebasin area (Figure 7.3). This view of the landscape, emphasizing its three-dimensional character created by elaboration of a valley network, points to the need to understand: (1) where the channel head is located within the valley network;