Final answer:
Peak discharge is the maximum rate of river flow after a precipitation event, represented as the highest point on a storm hydrograph. It is crucial for flood management and infrastructure design.
Step-by-step explanation:
Peak discharge on a storm hydrograph represents the maximum rate of water flow (discharge) in a river following a precipitation event, such as rainfall or snowmelt. The hydrograph itself is a graph showcasing how a river's flow rate changes over time in response to a precipitation event. During a storm, drainage systems accumulate water, and the increased volume subsequently leads to a rise in river flow. The peak discharge is noted as the highest point on the graph and indicates the moment when the river reaches its maximum flow rate.
An example of peak discharge can be seen in the flood event of 9/23/2009, where a discharge of 21,200 cubic feet per second (cfs) was recorded. This value would be plotted at the highest point on the hydrograph during that event. Understanding the peak discharge is critical for flood management and predicting future hydrologic behavior in waterways. This concept is also instrumental when designing infrastructure such as dams, bridges, and levees to withstand potential flood events.