FLOOD04263

• County: Statewide
• Basin: Statewide
• Title: Design of Open Channels
• Date: 10/1/1977
• Prepared By: USDA Soil Conservation Service
• Floodplain - Doc Type: Educational/Technical/Reference Information

e

e

e

Plan data. - - The plan should show the location of the existing channel;
base line; cross sections; apparent property lines; generall.and use of
adjacent areas; bench marks; existing vegetation, noting general size
and specie, especially individual trees with greater than 6-inch diameter
and trees with less than 6-inch diameter that are unique or not common
for the watershed; roads, bridges and culverts; houses and institutional
buildings that are within or adjacent to right-of-ways; and any utilities
that may fall within the planned right-of-way. The base line should
show either azimuths, bearings, or deflection angles. They may be
shown as traced from aerial photographs. The direction and stationing
of the cross sections should be shown on the plan. The plan may be
made from an overlay of corrected 8-inch aerial photographs, plane
table sheets, or a plot made from transit survey field notes. If coordinates
are used, they should be shown on the plan.

Profile. - - Data obtained from the survey of valley cross sections and
cross sections surveyed at hydraulic structures, supplemented if necessary
with information from available USGS quadrangle sheets, should be
used to plot a profile of the existing channel and valley. Standard sized
sheets of profile paper or plan-profile paper should be used for this
purpose, to facilitate preparation of preliminary drawings. (See Figure
2-1.)

The profile should show the water surface of the design flood for present
conditions; the present ground line; the existing bottom grade; cross
section locations; soil investigation sites; the elevation and location
of any exposed or underground utili ties, roads and existing or proposed
bridges and culverts, junctions of tributaries; etc.

It may be desirable to plot separate profiles for use in considering existing
and planned conditions if it is expected that existing alignment will
be changed significantly.

Cross sections. - - Cross sections should show any existing channels;
the intersection with the base line; the elevation of the design flood
for existing conditions; the elevation of any exposed or underground
utilities; and any existing or proposed bridges.

Preparation of Preliminary Drawings

Preliminary drawings may include plan, profile and cross sections of
all channel work proposed for the project. In the case of large complex
channel systems, it may be expedient to show only representative channels
in this degree of detail in order to reduce the bulk of the preliminary
document.

In either case the following preliminary design data should be shown
in addition to the survey data collected as shown above:

2-9