How to use the river mixing concentration calculator
Find the pollutant concentration after a tributary joins a river, assuming complete mixing. Enter river flow, river pollutant concentration, tributary flow, tributary pollutant concentration in the fields above; the mixed concentration, pollutant mass flow are computed instantly and plotted on the chart so you can see how the answer changes.
Common searches this calculator answers include “river mixing concentration”, “tributary pollution mixing”, “downstream concentration”, “calculate river mixing concentration”, “find mixed concentration”.
Formula
Variables
- Q1 — River flow (m³/s)
- C1 — River pollutant concentration (mg/L)
- Q2 — Tributary flow (m³/s)
- C2 — Tributary pollutant concentration (mg/L)
Worked example
With river flow = 10 m³/s, river pollutant concentration = 2 mg/L, tributary flow = 5 m³/s, tributary pollutant concentration = 10 mg/L, the calculator gives mixed concentration ≈ 4.666667 mg/L; pollutant mass flow ≈ 6,048 kg/day.
Frequently asked questions
What is the river mixing concentration calculator used for?
Find the pollutant concentration after a tributary joins a river, assuming complete mixing. It helps with questions such as “river mixing concentration”, “tributary pollution mixing”, “downstream concentration”.
What is the formula for the river mixing concentration calculation?
Mixed concentration (mg/L) = (Q1 × C1+Q2 × C2) / (Q1+Q2). Pollutant mass flow (kg/day) = (Q1 × C1+Q2 × C2) × 86.4. Here Q1 is river flow (m³/s), C1 is river pollutant concentration (mg/L), Q2 is tributary flow (m³/s), C2 is tributary pollutant concentration (mg/L).
What inputs do I need for the river mixing concentration calculator?
You need river flow in m³/s, river pollutant concentration in mg/L, tributary flow in m³/s, tributary pollutant concentration in mg/L. Each field is pre-filled with a typical example so you can see how the result responds as you edit the numbers.
How do I use the river mixing concentration calculator?
Type values into the input fields. Results and the chart update instantly. Use Reset to restore the example values, Copy results to paste them elsewhere, or Share to copy a link that preserves your inputs.
Is the river mixing concentration result exact?
Calculations use standard formulas and double-precision arithmetic, then display about seven significant figures. Real-world measurements carry uncertainty, so treat results as estimates unless your inputs are exact.