V. Create SCS Curve Number Map

I.Open and Prepare Map Data
- a.Open ArcGIS
- b.Open a new empty map
- c.Open Data Layers
  - i.Adding a single layer
  - ii.Adding multiple layers
- d.Organizing data layers
- e.Viewing the whole Map
  - i.Opening the "Tools" toolbar
  - ii.Zooming in ArcGIS
- f.Saving the Project
II.Setting Color and Symbol Schemes
III.Delineate Watershed
- a.Open Editor Toolbar
- b.Organize Layers for best view of topography
- c.Draw the watershed boundary
  - i.Delineate the watershed manually using the editor
  - ii.Calculate the Area of the Watershed
IV.Overlay Soil and Landuse data
V.Create SCS Curve Number Map
- a.Finish Curve Number Lookup Table
- b.Create and symbolize Curve Number layers
  - i.Create layer showing areas with a Curve Number of 100
    - 1.Using Definition Query tool
    - 2.Create Layer File
  - ii.Create the remaining Curve Number layers (“CN_84”, “CN_80”, etc.)
    - 1.Create layer showing areas with a Curve Number of 84
    - 2.Create layer file
  - iii.Group and symbolize all curve number layers
    - 1.Group the layers
    - 2.Symbolize “Curve Number” layer
- c.Complete Composite Curve Number Table
  - i.Calculate area of land with curve number value of 100
  - ii.Repeat steps for each individual remaining curve number layer to complete the Composite Curve Number Table
VI.Creating a Layout
- a.Setting Print Area
- b.Layout View
- c.Page orientation
- d.Setting map properties
- e.Adding map features

The Curve Number is a number that is used to relate rainfall to direct runoff. Once you have the Curve Number for your watershed you can follow the NRCS Method to calculate the runoff. Curve Number is primarily a function of soil type and land use. We can tell the GIS to determine the Curve Number at every point in the watershed and also find the corresponding area for each land use and Curve Number. Using this data we can find what we are looking for, which is the weighted average Curve Number for the watershed.

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