Weighted Curve Number Calculator for a Basin

Calculate the overall curve number of a basin by weighing the curve numbers of subbasins by their areas:
\[ CN_{weighted} = \frac{\sum (CN_i \times \text{Area}_i)}{\sum \text{Area}_i} \]

* Enter the area (in consistent units) and curve number for each subbasin.

Step 1: Enter Subbasin Data

Area of Subbasin 1:

Example: 10 (units: km² or any consistent unit)

Curve Number for Subbasin 1:

Example: 75

Area of Subbasin 2:

Example: 20 (same units as above)

Curve Number for Subbasin 2:

Example: 80

Area of Subbasin 3:

Example: 15 (same units as above)

Curve Number for Subbasin 3:

Example: 65

Step 1: Enter Subbasin Data

Calculated Weighted Curve Number