---
title: "Bransby Williams Method"
canonical: "https://help.innovyze.com/space/infodrainage2020v2/16416873/Bransby%20Williams%20Method"
format: markdown
---
### **Parameters**

**Flowpath Length - **The length of the Sheet flow path.

**Land Slope - **The slope of the hydraulic grade line.

**Area - **The catchment area.

### **Calculation**

![image](media://97706c50-f46d-4246-80b1-df8eb245fa2b)


where:

L  = Length of overland flow (Km)

A = Area (Km<sup>2</sup>)

S = Average catchment slope (%)

t<sub>c </sub>= time of concentration (hrs)