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Modeling Multiple Sub-area Watersheds

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					          WinTR-55
    Small Watershed Hydrology
   Intermediate WinTR-55 Training
Modeling Multiple Sub-area Watersheds
           Course Outline
Intermediate WinTR-55 Training
• Multiple Sub-area Watersheds
  – Sub-area / Reach Concepts
  – Developing data for Multiple Sub-area
    Watersheds
  – Entering data and running the program
  – Interpreting Output


               WinTR-55 Multiple Sub-Areas
          Lesson Objectives
Upon completion of this lesson you will be able to :
• Describe the relationship between reaches and sub
  -areas in the modeling process
• Develop input data for multiple sub-area
  watersheds and stream reaches
• Input stream reach data into WinTR-55
• Run WinTR-55
• Interpret Output


                 WinTR-55 Multiple Sub-Areas
Sub-Area and Reach 
     Concepts
Sub-area/Reach Concepts
                                            • Watershed - system
                                              of sub-areas and
            B                                 reaches
    A
                                            • Sub-areas -
                                              watersheds that
        c




                 C                            generate runoff
            h1
         eac




D
        R




                                            • Reaches - represent
                 Reach 2e




                                              watershed flow paths
        E                                     (stream channels) or
                                              structures

                            WinTR-55 Multiple Sub-Areas
   Sub-area/Reach Concepts
• Watershed - system of sub-areas and reaches
• Sub-areas - generate runoff
               - feed into the upstream end of reaches
• Reaches or Routing Elements- represent watershed
  stream flow paths or structures
   – Channel Routing elements - Stream Reaches
   – Structure Routing elements - Reservoir/Structure
     Reaches
• Watershed Outlet - downstream end of the watershed
  (required for all watersheds)

                    WinTR-55 Multiple Sub-Areas
                         Schematics
Su
  b-a
         rea
                   A
                                Reach
                              (storag      1a
                                      e routi
                                             ng)
                                                         -ar ea B
                                                    Sub
     Sub-area C




                             2c ng)
                         ach ti
                   Re h Rou
                     ac
                   (Re                  Legend:
                                                   Storage Area
Outlet
                                                   Sub-Area Inflow Points
                           WinTR-55 Multiple Sub-Areas
        Data Requirements
• Identification Data - User, State, and County
• Dimensionless Unit Hydrograph
• Storm Data – for specific County/State
• Sub-area Data - Name, flows to reach/outlet, area,
  runoff curve number, & time of concentration
• Reach Data -Name, receiving reach/outlet, reach
  length, Manning’s “n”, friction slope, bottom
  width, average side slopes


                 WinTR-55 Multiple Sub-Areas
Adding Sub-areas
Adding Sub-areas




   WinTR-55 Multiple Sub-Areas
   Adding Stream Reaches
             and
Developing Stream Reach Data
    Adding Stream Reaches
•   WinTR-55 Main Window
•   Reach Data Window
•   Reach Flow Path Window




             WinTR-55 Multiple Sub-Areas
Watershed Schematic
              Upper Main Creek Sub-area           County Road Branch Sub-area
            (stream embedded in sub-area)        (stream embedded in sub-area)


                                                                             Upper East Trib Sub-area
                                                                         (stream embedded in sub-area)
  Upper West Branch Sub-area
(stream embedded in sub-area)

                                     Middle Main Creek Sub-area
                                        Main Stem 1 Reach

                                                       Lower East Trib Sub-area
           Lower West Branch Sub-area                        East Reach
                  West Reach




                                   Lower Main Creek Sub-area
                                      Main Stem 2 Reach




                                            OUTLET

                       WinTR-55 Multiple Sub-Areas
WinTR-55 Main Window




      WinTR-55 Multiple Sub-Areas
    Adding Stream Reaches
•   WinTR-55 Main Window
•   Reach Data Window
•   Reach Flow Path Window




             WinTR-55 Multiple Sub-Areas
     Stream Reach Data
• Data compiled prior to input:
  – Reach Name
  – Name of receiving (or downstream) reach
    (could be Outlet)
  – Cross-section data:
     •   Manning’s “n”
     •   Friction slope
     •   Bottom Width
     •   Average side slopes

                   WinTR-55 Multiple Sub-Areas
Reach Data Window




    WinTR-55 Multiple Sub-Areas
Reach Data Window




    WinTR-55 Multiple Sub-Areas
Plotted Channel Rating




      WinTR-55 Multiple Sub-Areas
Computing Stream Reach Ratings

• Manning’s Equation for Channel Flow:




  Q = discharge (cu ft/s)                 r = hydraulic radius = A/pw
  A = cross-sectional flow area (sq ft)   pw = wetted perimeter (ft)
  s = slope of hydraulic grade line (channel slope, ft/ft)
  n = Manning’s roughness coefficient for open channel flow

                      WinTR-55 Multiple Sub-Areas
Trapezoidal Cross-Section

                       TW




                                               1
                 D                         z
     1
         z

                       BW




             WinTR-55 Multiple Sub-Areas
Trapezoidal Cross-Section ?




        WinTR-55 Multiple Sub-Areas
Low Flows


                      Sideslope




        BW


WinTR-55 Multiple Sub-Areas
High Flows

                              Sideslope


 Bottom Width




WinTR-55 Multiple Sub-Areas
Non-representative Section




        WinTR-55 Multiple Sub-Areas
            Reach Routing
• Muskingum-Cunge
  Routing Method                            Reach Inflow
  – Alters the hydrograph
    as it flows through a
    reach, utilizing the
    rating information
                                                  Reach
                                                  Outflow




                  WinTR-55 Multiple Sub-Areas
Reach Data Window




    WinTR-55 Multiple Sub-Areas
Quick Help




WinTR-55 Multiple Sub-Areas
    Adding Stream Reaches
•   WinTR-55 Main Window
•   Reach Data Window
•   Reach Flow Path Window




             WinTR-55 Multiple Sub-Areas
Reach Flow Path Window




       WinTR-55 Multiple Sub-Areas
Capabilities and Limitations
    Capabilities & Limitations

•   Number of sub-areas      1 - 10
•   Number of reaches        0-10
•   Types of reaches         Channel or Structure
•   Channel Reach
    Routing Procedure         Muskingum-Cunge




                  WinTR-55 Multiple Sub-Areas
Questions?
  Entering Data, Running the 
Program and Interpreting Output
  Demonstration Problem #3
     Multiple Sub-area Watershed
          with Stream Reach
 Demonstration Problem #3
• Road commissioner needs to size a
  culvert at the county road downstream
  of the proposed subdivision in
  Williamson County, Illinois
• The culvert needs to be large enough to
  handle “future condition” flows for the
  10-year storm event

             WinTR-55 Multiple Sub-Areas
Demonstration Problem #3
                                         Culvert

                         C




                                     c
                                 ch 2
                             Rea
                    h 1b
                  ac
               Re


      A       B

       WinTR-55 Multiple Sub-Areas
           Sub-area Data
Sub-area    Area (acres)             CN      Tc(hours)
   A            24.5                 77       0.237
   B            62.4                 79       0.334
   C            64.3                 73       0.423
Location: Williamson County, Illinois




               WinTR-55 Multiple Sub-Areas
        Stream Reach Data
                Reach 1b                      Reach 2c
Reach Length     2,050 ft                      2,320 ft
 Manning’s n       0.04                          0.04
Friction Slope 0.0146 ft/ft                  0.0151 ft/ft
Bottom Width      6 feet                       10 feet
 Side Slopes       2:1                          2.5:1
Location: Williamson County, Illinois
               WinTR-55 Multiple Sub-Areas
                           Schematic
Legend:                                                 Outlet
                                                               Culvert
          Storage Area
                                                    C




                                                              2c
          Sub-Area Inflow Points
                                             r ea




                                                        Reach
                                          -a
                                     S ub      C

                                          h 1b B
                                     e ac        ea
                                   R          ar
                                           b-
                        e a
                            A           Su
                  b-
                     ar
                           A           B
               Su
                            WinTR-55 Multiple Sub-Areas
    Adding Stream Reaches
•   WinTR-55 Main Window
•   Reach Data Window
•   Reach Flow Path Window




             WinTR-55 Multiple Sub-Areas
WinTR-55 Main Window




      WinTR-55 Multiple Sub-Areas
Reach Data Window




    WinTR-55 Multiple Sub-Areas
Reach Flow Path Window




      WinTR-55 Multiple Sub-Areas
Run WinTR-55




  WinTR-55 Multiple Sub-Areas
   Output




WinTR-55 Multiple Sub-Areas
      Discussion Questions
For the 10-year storm event:
1. What is the discharge due to runoff from
   each sub-area?
2. What is the total discharge at the outlet of
   each sub-area?
3. What is the total discharge at the watershed
   outlet?
4. What is the design discharge for the culvert
   replacement?

               WinTR-55 Multiple Sub-Areas
Solution
   1.
   2.
   3.
                                     qpeak from Sub-Area A
   4.                                qpeak from Sub-Area B
                                     qpeak from Sub-Area C

                                   = Total qpeak at Outlet A
                                     + qpeak from Reach 1b
                                   = Total qpeak at Outlet B
                                     + qpeak from Reach 2c
                               Total q for at qpeak at Outlet C
                                   = Total Watershed Outlet
                          Design qpeakpeak culvert replacement




           WinTR-55 Multiple Sub-Areas
Questions?
  Entering Data, Running the 
Program and Interpreting Output
     Example Problem #3
     Multiple Sub-area Watershed
          with Stream Reach
    Example Problem 



                       W
                        es are
                    Su
                                                ork 




                          t F a
                       b-
                                          ast F ea




                             or
                                         E




                               k 
                                             b-ar
Dry Creek 


                                          Su
Sub-area




              C reek
        Dry             g)
                R outin
            ch
       ( Rea



                 WinTR-55 Multiple Sub-Areas
          Sub-Area Data
   Sub-area          Area              CN    Tc
West Fork              175              77   0.420
East Fork              200              73   0.445
Dry Creek               70              66   0.209
Location: Richland County, South Carolina




              WinTR-55 Multiple Sub-Areas
        Reach Data
Dry     Length         Manning n        Friction
                                         Slope
Creek
            540’                0.065    .003 ft/ft
        Bottom                  Side Slopes
         Width
             20’                              55:1




          WinTR-55 Multiple Sub-Areas
               Questions
For the 100-year storm event:
1. What is the TOTAL peak discharge at the
   outlet of each sub-area?
2. What is the total peak discharge at the
   watershed outlet?
3. What is the peak discharge at the top and
   bottom of the DryCreek Reach?
4. Why is the peak discharge at the bottom of
   the Dry Creek Reach different from the total
   discharge at the watershed outlet?
               WinTR-55 Multiple Sub-Areas
    Adding Stream Reaches
•   WinTR-55 Main Window
•   Reach Data Window
•   Reach Flow Path Window




             WinTR-55 Multiple Sub-Areas
Watershed Peak Table




     WinTR-55 Multiple Sub-Areas
Questions?
                 Summary
You should now be able to :
• Describe the relationship between reaches and sub
  -areas in the modeling process
• Develop input data for multiple sub-area
  watersheds and stream reaches
• Input the data into WinTR-55
• Run WinTR-55
• Interpret Output


                 WinTR-55 Multiple Sub-Areas

				
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