Question

Predict the streamflow hydrograph for the North Branch Ralston Creek (A year 7-hour design storm 3.01 mi') for the 10- SCS 10-year 7-hour Design Storm for North Branch Ralston Creek Watershed Time 11n l ime in 0.0 0.14 0.14 0.20 0.30 0.34 0.60 0.90 1.60 0.80 0.40 0.20 0.14 0.12 0.12 0.5 4.0 5.0 2.5 6.0 6.5 3.5 Assume the following basin characteristics -index is 0.50 in/hr for the storm Time of concentration: 56 minutes Use the SCS dimensionless unit hydrograph method (see class handout and Table 8.8.1) to compute a. The rainfall excess hyetograph Pe (t) (in inches) (see Problem#46) b. The SCS unit hydrograph U (t) (in cfs). Report the unit hydrograph results in a table usinga time step of tR c. The 30-min SCS unit hydrograph U (t) (in cfs). i.e., tR' 30 min. Report the unit hydrograph results in a table using a time step of tr. [Hint: Example 8.5.1, p259, Mays]

Answer 1

Rolution Tinep SA - SB addition loroinale | so min | -T- T-30 in D 2 30 min SA 0.5 0 0.1 0.14 15|0,2 | 0-1Ч | 0,34 | o 14 6-2 5.3 5338 3 3 |ь.6 | о.uy 11.oy | 0.44 o. 6 3.5 9685868 2-691 09 S 8 5538.5 238 6,5 |0.12 | 2:58 | Згр |3.58 | 1-12 子10·미 3.14 | 3.2b | 3.14 | 6-12 o-12R 0.930 346s