In the example hypothesis, what is predicted about river width?

• A. It will decrease
• B. It will increase
• C. It will stay the same
• D. It will fluctuate randomly

Answer: (B)

A hypothesis in geography often predicts a clear directional change in a feature like river width in response to another variable. Here, the idea is that as the amount of water flowing in the river increases (for example downstream where discharge grows or during flood conditions), the river has more energy to erode its banks and widen the channel. That makes a prediction that the width will increase logical and testable.

Why the increase is the best answer: with higher discharge, the river needs to carry more water, so erosion along the banks tends to widen the channel, and the cross-sectional area expands to accommodate the greater flow. This is a common pattern described in hydraulic geometry—width tends to rise with increasing discharge and distance downstream, producing a broader channel.

The other possibilities are less consistent with typical river behavior. A decrease would require unusual conditions that narrow the channel as flow increases, which isn’t the usual expectation. Staying the same would imply no relation at all between discharge and width, contradicting observed patterns in most rivers. Fluctuating randomly would indicate no predictable trend, but hypotheses are framed to predict a consistent direction, not random changes.