Level Pool Routing Calculator

Route inflow hydrographs through detention basins and reservoirs using the Modified Puls (Storage-Indication) method. Calculate peak attenuation, lag time, and maximum storage for detention pond design.

Route Hydrograph Through Storage

For educational purposes only. Not a substitute for professional engineering judgment.

Input Parameters

Inflow Hydrograph

Define the inflow hydrograph to route through storage

Choose how to define the inflow hydrograph

cfs

Maximum inflow discharge

min

Time from start to peak inflow

min

Total duration of inflow hydrograph

A trapezoidal hydrograph will be generated with linear rise to peak and gradual recession.

Storage-Discharge Relationship

Define the stage-storage-discharge relationship for the detention facility

Choose how to define the storage-discharge curve

ft

Average length of pond

ft

Average width of pond

ft

Maximum water depth

ft²

Outlet orifice cross-section

Discharge coefficient (Cd)

Storage-discharge curve generated assuming rectangular pond with orifice outlet. Q = Cd * A * sqrt(2 * g * h)

Routing Parameters

Configure the routing time step and initial conditions

min

Routing calculation interval

acre-ft

Storage volume at time = 0

cfs

Outflow discharge at time = 0

Modified Puls Method Overview

The Modified Puls (Storage-Indication) method routes flood hydrographs through reservoirs and detention basins. It assumes a level pool where outflow is a function of storage only.

Key Equations

  • Storage-Indication: SI = 2S/dt + O
  • Routing equation: (2S2/dt + O2) = (2S1/dt - O1) + I1 + I2

Where:

  • S = Storage volume (acre-ft)
  • O = Outflow discharge (cfs)
  • I = Inflow discharge (cfs)
  • dt = Routing time step (minutes)

Common Applications

Detention Basin Design

Size storage to meet peak flow reduction targets

Reservoir Flood Routing

Determine outflow hydrograph and peak water level

Dam Safety Analysis

Evaluate spillway capacity during design floods

Stormwater Management

Demonstrate compliance with post-development limits

Design Tips

1

Time step selection: Use a time step no larger than Tp/5 where Tp is the time to peak. Smaller time steps provide better accuracy but increase computation.

2

Storage-discharge curve: Ensure your data covers the full range of expected water levels. The method will extrapolate if values exceed the provided range.

3

Volume balance: Check that total inflow volume equals total outflow volume. Errors greater than 1% may indicate numerical instability.

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