Peak discharge on a hydrograph indicates the maximum flow of water in a river following a rainfall event.

Peak discharge is a vital feature of a hydrograph, which is a graphical representation of the rate of flow (discharge) against time at a specific location in a river or other channel. Discharge is commonly measured in cubic meters per second (cumecs). The peak discharge point on this graph signifies the moment when water flow reaches its highest level, typically occurring after a significant rainfall event when the river is carrying its largest volume of water.

Understanding peak discharge is important for several reasons:

1. Flood Prediction: High peak discharge values suggest that the river may exceed its capacity, potentially leading to overflow and flooding. This information is critical for authorities to implement flood prevention measures and to issue timely warnings to communities at risk.

2. Catchment Characteristics: The behavior of peak discharge can reveal insights into the river’s catchment area. For instance, a rapid rise to peak discharge may indicate a steep, small, or urban catchment with minimal vegetation, which can impede the absorption of rainfall. Conversely, a gradual increase might suggest a larger, flatter, or rural catchment that has more vegetation to slow down and absorb rainfall.

3. Long-Term Trends and Climate Change: Monitoring changes in peak discharge over time can help identify long-term trends and the potential impacts of climate change. For example, an increase in the frequency or intensity of peak discharges could indicate a rise in extreme weather events associated with global warming.

In summary, peak discharge is a crucial component of hydrographs, providing essential information about river flow, flood risk, catchment characteristics, and the potential impacts of climate change.