BOARD01965

• Board Meeting Date: 3/22/2005
• Description: Flood Section - Presentation of the CWCB's Draft Rules and Regulations for Regulatory Floodplains in Colorado
• Board Meetings - Doc Type: Memo

Term
Triangulated
Irregular Network
Model (TIN)

Topography

Universal Transverse
Mercator (UTM)

Vector Images

Water Surface Profile

Definition
A significant alternative to the regular raster of a DEM that has been
adopted in numerous GIS programs and automated mapping and
contouring packages. The TIN model was developed in the early 1970's as
a simple way to create a surface from a set of irregularly spaced points.

Configuration (relief) of the land surface; the graphic delineation or
portrayal of that configuration in map form, as by contour lines.

The Universal Transverse Mercator (UTM) projection and grid system
was adopted by the U.S. Army in 1947 for designating rectangular
coordinates on large-scale military maps. UTM is currently used by the
United States and NATO armed forces. The UTM system divides the earth
into 60 zones each 6 degrees oflongitude wide.

A collection of connected lines and curves that produce objects. When
creating a vector image in a vector illustration program, node or drawing
points are inserted and lines and curves connect notes together. This is the
same principle as "connect the dots." Each node, line and curve is defined
in the drawing by the graphics software by a mathematical description.
Every aspect of a vector object is defined by math included node position,
node location, line length and on down the line. Text objects are created
by connecting nodes, lines and curves. Every letter in a font starts out as a
vector object. Vector images are object-oriented while raster images are
pixel oriented.

A graph that shows the relationship between the vertical elevation of the
top of flowing water and of the streambed with the horizontal distance
along the stream channel.

Rule 5. State Reeulatorv Floodplain: The regulatory floodplain is the I OO-year floodplain. For the
purposes of these Rules, the term "Storm or Floodwater Runoff Channels" is synonymous with the
term 100-year floodplain. Sections 24-65.1-101 & 24-65.1-202(2)(a)(I) and 24-65.1-302(1)(b)&(2)(a)
and 24-65.1-403(3) and24-65.l-404(3), C.R.S. (2004) deem the designation of floodplains a matter of
statewide importance and interest and give the CWCB the responsibility for the designation and
approval of the 100-year floodplain.

Rule 6. Standards for Delineation of Reeulatorv Floodplain Information:

A. Intent ofthis Rule. This Rule contains standards for approximate and detailed regulatory
floodplain determinations in Colorado. This Rule and its subsections within each rule are
supported by technical standards and specifications herein and additional technical standards in
Appendix A (base mapping), Appendix B (hydrology), and Appendix C (hydraulics).

B. Level of Detail. This rule contains standards for approximate and detailed floodplains.

10