Basin Shape

Basin shape also has an influence on magnitude and timing of the peak flow at the basin outlet.

Consider two basins of equal area where one is long and narrow, and the other is more round. Then consider runoff traveling from the farthest point in each basin to their respective outlets. The runoff in the more round basin will arrive more quickly at the basin outlet.

In addition, water from multiple locations in this basin is more likely to arrive at the outlet at the same time, resulting in a greater peak flow. By contrast, in a longer, narrower basin, water from multiple locations is less likely to arrive at the same time.