Explain headward erosion and how it leads to river capture, identifying features and consequences.

1.1.2 One possible factor from FIGURE 1.1 that could have resulted in River A capturing River B is that River A has a steeper gradient or higher erosive power, as indicated by the "Headward erosion" label on River A.

1.1.3 Headward erosion contributes to river capture by allowing a more energetic river (the captor stream) to erode backwards through a watershed divide. As it erodes, it eventually intercepts the headwaters of a less energetic neighboring river (the captured stream), diverting its flow into the captor's channel.

1.1.4

• Feature D: Elbow of capture
• Feature E: Wind gap or Dry valley

1.1.5 Three physical changes that will occur in River A as a result of river capture are:

• Increased volume of water: River A will gain the discharge from the captured section of River B, leading to a larger overall flow.
• Increased velocity: With a greater volume of water, the river's flow speed will generally increase, especially if its gradient remains favorable.
• Increased erosive power: The higher volume and velocity will give River A more energy to erode its bed and banks, leading to greater vertical and lateral erosion.