Question

Calculation of peak discharge (10) B. Tube The rational method is the most common method for estimating peak stormflow discharge from small watersheds. (see pages 151-152, in text). metric-unit version of the equation (p. 151, eq. 6.6). 1. The text gives The older U.S. rational method equation (but still used!) is: "q =Ci A", where q is the peak flow from a given storm (cfs), C is a runoff constant (dimensionless), i is the intensity of the rainfall (in/hr), and A is the watershed area a (acres). Using a dimensional analysis, show why there need not be a conversion factor with this equation (i.e., Km = 1 for English units). prove 2. Use the rational method (English units) to show the difference between peak discharges for a 2-acre lot of heavy-clay soil in Lafayette, LA. For a 6-hr, 25- year design storm, use the NOAA Precipitation Frequency Data Server (PFDS) (link provided in Canvas) to calculate the peak discharges (cfs) for the following scenarios: Wooded lot a. b. Cultivated in crop Impervious parking lot C. For each scenario, give a reference for the runoff coefficient (C) that you are S nagem using.

what does PFDS needed mean

Answer 1

The Precipitation Frequency Data Server (PFDS) is a kind of server developed to understand the Precipitation Frequency Estimate of a region by just pointing and clicking on the region given in the map loaded in the server.

Now the question comes what is meant by Precipitation Frequency Estimate?

Precipitation Frequency Estimate is a measure of  the depth of precipitation at a specific location for a specific duration that has a certain probability of occurring in any given year.

In other words precipitation frequency estimate answers the following question:

Given the amount of precipitation received by a geographical region in the form of drizzle,rain,snow etc, for a certain period of time say for 5 years what is the probability of that region to receive a certain of precipitation in a certain year?

The server from where we find this information is known as Precipitation Frequency Data Server (PFDS).

Kindly use comment box if its still not clear what a PFDS is.