Detention pond calculator

Calculate stormwater detention volume requirements

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The Detention Pond Calculator helps civil engineers determine required detention pond volumes for stormwater management. Calculate storage capacity needed to control peak runoff rates and meet local drainage requirements.

Detention ponds temporarily store stormwater runoff and release it at controlled rates to prevent downstream flooding. Proper sizing ensures adequate storage capacity while minimizing land use and construction costs.

Enter drainage area, runoff coefficient, rainfall intensity, and detention duration to calculate required detention volume. The calculator uses the Rational Method to determine peak flow and converts to storage volume based on detention time, helping design effective stormwater management facilities.

Features

Everything you need

Detention volume calculations
Peak flow determination
Runoff coefficient inputs
Design storm intensity support
Detention duration considerations
Rational Method application
Imperial and metric units

How it works

Simple workflow

1
Enter drainage area
2
Specify runoff coefficient
3
Input design rainfall intensity
4
Set detention duration
5
Review calculated detention volume

Use cases

Built for real-world scenarios

Stormwater management

Design detention ponds to control peak runoff rates and meet drainage requirements.

Site development

Calculate detention requirements for new development and impervious surface increases.

Permit applications

Generate detention volume calculations for stormwater management permits.

Flood control

Size detention facilities to prevent downstream flooding during storm events.

FAQ

Frequently asked questions

Volume = Peak Flow × Detention Time. Peak Flow = C × I × A (Rational Method). For 5 acres, C=0.6, I=3 in/hr, 60-min detention: Q = 9 cfs, Volume = 9 × 3,600 = 32,400 ft³.

Detention ponds temporarily store water and release it (dry between storms). Retention ponds maintain permanent water (wet ponds). Detention controls peak flow, retention provides water quality treatment.

Common: 10-year, 25-year, or 100-year storms depending on local requirements. Intensity varies by location and duration. Check local drainage criteria for specific requirements.

Typical detention: 24-72 hours depending on local requirements. Longer detention reduces peak release rate but requires larger volume. Balance storage needs with release rate limits.

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