1. What Is The Peak Discharge Per Unit Catchment Area Given Unit Hydrograph Width At 50 Percent Peak Discharge?

This calculation determines the peak discharge per unit catchment area based on the width of the unit hydrograph at 50% of the peak discharge. It's a fundamental relationship in hydrological analysis for predicting flood peaks from rainfall events.

2. How Does The Calculator Work?

The calculator uses the formula:

Where:

• \( Q \) — Peak discharge per unit catchment area (m³/s)
• \( W_{50} \) — Width of unit hydrograph at 50% peak discharge (mm)

Explanation: This empirical relationship establishes the inverse correlation between hydrograph width and peak discharge, with the exponent 1/1.08 accounting for the non-linear nature of this relationship.

3. Importance Of Peak Discharge Calculation

Details: Accurate peak discharge estimation is crucial for hydraulic structure design, flood forecasting, watershed management, and emergency planning. It helps determine the maximum flow rates that drainage systems must handle.

4. Using The Calculator

Tips: Enter the width of the unit hydrograph at 50% peak discharge in millimeters. The value must be greater than zero. The calculator will compute the corresponding peak discharge per unit catchment area.

5. Frequently Asked Questions (FAQ)

Q1: What is a unit hydrograph?
A: A unit hydrograph represents the direct runoff response of a watershed to one unit of effective rainfall occurring uniformly over the drainage area for a specified duration.

Q2: Why use the 50% width specifically?
A: The width at 50% peak discharge provides a stable and reproducible measure of hydrograph shape that is less affected by measurement errors than other points on the hydrograph.

Q3: What are typical W50 values?
A: W50 values vary significantly based on watershed characteristics, ranging from less than 1 mm for small urban catchments to over 10 mm for large rural watersheds.

Q4: Are there limitations to this formula?
A: This empirical relationship may need calibration for specific regions or watershed types and may not account for all hydrological complexities in extreme conditions.

Q5: How is this used in practical applications?
A: Engineers use this relationship to estimate peak flows for designing culverts, bridges, stormwater systems, and for floodplain mapping and management.