A triangular DRH due to a 6-h storm in a catchment has a time base of ...
Understanding the DRH and Unit Hydrograph
A Direct Runoff Hydrograph (DRH) represents the response of a catchment to a specific rainfall event. In this scenario, we have a triangular DRH from a 6-hour storm with:
- Time Base: 100 hours
- Peak Flow: 40 m³/s
- Catchment Area: 180 km²
Calculating the Unit Hydrograph Peak Flow
To find the peak flow of the unit hydrograph, we need to understand the relationship between the catchment area and the peak flow of the DRH.
- Unit Hydrograph: It represents the runoff produced by 1 cm of effective rainfall over the catchment in a unit time, typically 1 hour.
- Peak Flow Calculation: The peak flow of the unit hydrograph can be calculated using the formula:
- Peak Flow (m³/s) = Peak Flow of DRH (m³/s) / Area (km²)
Applying the Values
1. Convert the Catchment Area:
- 180 km² = 180,000,000 m²
2. Calculate the Peak Flow:
- Peak Flow of the Unit Hydrograph = 40 m³/s / 180 km²
- Since 1 km² = 1,000,000 m², the area in m² is considered in the flow calculation.
3. Final Calculation:
- Peak Flow of Unit Hydrograph = 40 m³/s / 180 = 0.222 m³/s (approximately).
Conclusion
The peak flow of the unit hydrograph for the given catchment is approximately 0.222 m³/s. This value is crucial for understanding how the catchment will respond to different rainfall events, enabling effective water management and flood control strategies.