Do a hydrograph analysis to determine the direct runoff characteristics for the North Branch Ralston Creek (drainage area of 3.01 square miles) during the flood on 17-18 July 1972. The direct runoff hydrograph estimated for this event (by baseflow separation using a digital filter) is available. The areal average rainfall estimates (based on the Thiessen polygon method) are also available. Use this information to compute the following:

1. Volume of direct runoff V_d (cfs-hours)
2. Depth of direct runoff r_d (in)
3. NRCS runoff curve number (CN)
4. The rainfall excess P_e hyetograph (in)
5. The effective storm duration t_r (hours)
6. The runoff coefficient C

Hint: After computing the depth of direct runoff r_d, use the spreadsheet you created in Problem #22 to determine CN with the Goalseek option (i.e., find a CN value that produces rainfall excess P_e that sums to r_d).