For the P-Q data below (series of annual maxima), for watershed 68013 (WS-13), in Reynolds, Idaho, calculate the runoff curve number.

1. Plot the data in the P-Q plane.

2. For each P-Q pair, use Eq. 17 in the runoff curve number paper to calculate potential retention S.

3. For each S, use Eq. 9 in the runoff curve number paper to calculate a set of CN's.

4. The calibrated curve number is the average of the set of CN's.

5. Use the calibrated CN obtained in step 4 and Eq. 10 in the runoff curve number paper to plot a curve in the P-Q plane. Vary P between 0 and 2. Note the constraint to Eq. 10.

6. Compare the curve plotted in step 5 with the raw P-Q data plotted in step 1.