Stormwater Management System Drawdown- 'Falling Head Equation'

by Ahmad Chehab

 

Submitted : Fall 2010

In this project I demonstrated the calculations required to determine the drawdown for retention/detention ponds. Drawdown is a phrase which refers to the volume of water in a pond decreasing as the water flows out. Although I applied different variations of this formula, the core equation I dealt with in this project is called the Falling Head Equation.  This equation has many applications and is used to calculate the drawdown of a pond through various shaped openings by slightly tweaking the formula for each orifice. I have provided calculations for four outflow structures: a rectangular-notch weir, a v-notch weir, a round orifice, and an underdrain.

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