2011-04-14_PERMIT FILE - C1980007A

• Permit No: C1980007A
• IBM Index Class Name: Permit File
• Doc Date: 4/14/2011
• Doc Name: STREAM CHANNEL PARAMETERS
• Section_Exhibit Name: Exhibit 55B Stream Channel Parameters and Changes Due to Mining-Induced Subsidence
• Media Type: D
• Archive: Yes

Stream Channel Parameters
Exhibit 558 and Changes Due to Mining - Induced Subsidence Page 3
EXISTING STREAM CHANNEL CHARACTERISTICS
The existing stream channel characteristics have been defined for various parameters, including
channel slopes, peak flow rates for a variety of frequencies of occurrence, flow velocities for each
of the frequencies, sediment transport regime, stage - discharge relationships, channel profiles, and
channel and over -bank stability.
The existing channel shapes were related to the dominant discharge (2 -year frequency of
occurrence). Sediment transport has been defined for each stream using the annual sediment load;
however, sediment transport is a long -term value and represents the full range of flows including
the 10 -year and 100 -year frequency peak discharges.
For each of the existing stream channels, many hydrologic and stream channel parameters were
defined and evaluated, including:
• 1. Mean annual runoff
2. Peak discharges for the 2 -year, 10 -year, and 100 -year frequency floods
3. Mean annual sediment yields
4. Average thalweg slopes
5. Channel characteristics for the dominant discharge (consisting of width and depth
relationships)
6. The range of the channel slopes from near mouth to upper reach
Other factors that influence the long -term channel characteristics include the forested area and
frequency of landslides.
2 Line following lowest part of a valley, i.e., invert of channel.
831 - 032.810 Wright Water Engineers, Inc.