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sci.streeter-phelps-oxygen-sag Calculator
Calculates dissolved oxygen sag curve downstream of a pollution discharge using the Streeter-Phelps model, identifying critical DO minimum and its location. A healthy river (DO > 6 mg/L) becomes critical when BOD loading causes DO to drop below 4 mg/L — the critical distance depends on deoxygenation and reaeration rate constants.
Inputs
Do Sat Mg L
Reference formula or conversion factor shown for context.
Do 0 Mg L
Reference formula or conversion factor shown for context.
L0 Mg L
Reference formula or conversion factor shown for context.
Kd Per D
Amount per unit of time or per unit quantity. Check the denominator before interpreting.
Kr Per D
Amount per unit of time or per unit quantity. Check the denominator before interpreting.
T Days
Duration of the process. Make sure units match the rate inputs (seconds, minutes, or hours).
Results
DO at time t (mg/L)
The computed duration or time value.
DO deficit Dt (mg/L)
Reference formula or conversion factor shown for context.
critical time tc (days)
The computed duration or time value.
critical DO (minimum, mg/L)
The smallest value in the dataset or feasible range.