ENV* K245 Water Resources Engineering home

  1. General Considerations
    1. runoff is one of the two major compartments that precipitation can fill (the other is infiltration)
    1. Note: The term runoff can include both channel flow and overland flow.
    2. sources of runoff
  2. Runoff is produced by an interaction of precipitation and watershed
    1. precipitation effects
    2. precipitation and flooding
    3. watersheds vs drainage basins
    4. basin characteristics affecting runoff
  3. Factors Affecting Runoff
    1. Effects of soil
    2. Effects of vegetation
    3. Erosion and rivers
    4. Flood protection
  4. Precipitation/Runoff Relations
    1. hydrographs
    2. streamflow quantities
  5. SCS Runoff Curve Number Procedure
    1. the Soil Conservation Service developed a procedure for estimating runoff from farms based on soil type, land use, etc
  6. Peak Flow Formulas
    1. The Rational Method (Section 7.6)
    2. SCS TR-20 and TR-55 Methods
    3. all methods assume 24h of rainfall
    4. we will look at the Graphical Peak Discharge Method first
    5. applicable to watersheds up to 20 mi2 or so
    6. the formula is given by equation 7.45 (p 396)
    7. to use method:
    8. tL = the lag time in hours

      L=length of watershed

      G=average slope (as a number)

      • then:

      tC = tL/0.6

      with S = 1000/CN - 10

  7. Storm Water Hydrographs
    1. definition
    2. surface flow within a watershed
    3. hydrograph components
  8. Unit Hydrographs
    1. the time constants define the shape of the hydrograph; you could argue as follows:
    2. this idea is the basis of the unit hydrograph

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ENV* K245 Water Resources Engineering home

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Anthony G Benoit
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