WETMAAP Technique 2
Trinity River - Element 1

Technique 2: Manual GIS
Element 1: Making Feature Overlays

Materials:

           1:24,000 scale 1993 Cove/ 1993 Anahuac, TX, USGS Topographic Quadrangle
           (3)   11"x 17" clear film overlays
           drafting tape
           Colored marker pens: Blue, Green, Orange

Exercise:          

           1.     Use 1:24,000 1993 Cove/ 1993 Anahuac, TX, IN, USGS Topographic Quadrangles

           2.     Use a clear film 11”x 17”overlay.

           3.     Tape the clear film overlay on top of the 1:24,000 scale map.  Tape at the top edge.

          4.     Use the Blue pen.

          5.     Use the Blue pen to make four “corner marks” (tick mark  ^) on the overlay, one at each corner of the study site.

          6.     Trace the shoreline of water bodies in Blue on the overlay.

          7.     At the bottom of the overlay (in blue) draw a short horizontal line and label beside it “Water Features.”

 Hint:     Use of a symbol with a short description beside it is a “key,” or means of identifying selected features.

          8.     Remove the “Water Features” overlay.

          9.     Use a second 11"x 17”clear film overlay.

         10.     Tape the clear film overlay on top of 1:24,000 scale map. Tape at top edge.

         11.     Use the Green pen.

        12.     Use the Green pen to make four “corner marks” (tick mark ^ ) on the overlay, one at each corner of the study site.

        13.     Trace the outline of the swamp with Green on the overlay.

        14.     At the bottom (in green) draw a short horizontal line the same length as the Blue line and label it “Swamps.”     

        15.     Remove the “Swamps” overlay.

        16.     Use the third 11" x 17” clear film overlay.

        17.     Tape the clear film overlay on top of the 1:24,000 scale map. Tape the top edge.

        18.     Use the Orange pen.                     

        19.     Use the Orange pen to make four “corner marks” (tick mark ^) on the overlay, one at each corner of the study site.           

        20.     Outline all marsh areas in Orange on the overlay.

        21.     At the bottom (in orange) make a small polygon and label it  “Marsh.”  Do not remove this overlay.

Hint:     Combining several single “key” items creates a “legend.” Every map should have a legend

       22.     Tape the “Water Features” and “Swamps” overlays one on top of each other, over the “Marsh” overlay.  Use the four corner marks to line-up (“register”) the overlays on top of each other.

Hint:     Tape one overlay at the bottom edge and the other overlay at the left or right edge. By attaching the overlays at opposite edges, you can flip the overlays up and down in various alignments.  You have created a manual GIS.