Question

what are the steps in create the MTO rational method, estimating a design flow for a water crossing

Answer 1

For estimation we require :

Rational Method
Flood frequency analysis
Hydrologic modeling and
Empirical formulae

Steps involved in MTO rational method :

Know the parameters and their U.S. and S.I. units to be used in the Rational Method equation

Calculate peak storm water runoff rate with the Rational Method equation, using either U.S. or S.I. units.

Place a given soil into one of the four SCS soil groups based on its measured minimum infiltration rate.

Place a given soil into one of the four SCS soil groups based on its description.

Determine a value of the Rational Method runoff coefficient bsed on land use, soil group, and slope of the watershed.

Calculate the overland sheet flow travel time for a watershed using the Manning Kinematic equation.

Calculate the shallow concentrated flow travel time for a watershed using the NRCS method
Be able to calculate the open channel flow travel time for a watershed using the Manning equation.

Know the form of the equation used for rainfall intensity as a function of storm duration for a specified return period.

Use Excel spreadsheets for preparing models.