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HYDRO20750
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Last modified
8/24/2016 8:41:59 PM
Creation date
11/20/2007 1:44:04 PM
Metadata
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Template:
DRMS Permit Index
Permit No
C1980007
IBM Index Class Name
Hydrology
Doc Date
7/5/2005
Doc Name
Evaluating the Effectiveness of Postfire Rehabilitation Treatments
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MCC
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DMG
Permit Index Doc Type
Correspondence
Media Type
D
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in-stream woody debris to fish has been realized, this <br />treatment has declined in popularity whereas in- <br />channel felling has increased in popularity. No eati- <br />matea onrock cage dame effectiveness were found but <br />it is known that they provide grade stability and <br />reduce velocities to drop out coarse sediment. Debris <br />basins are designed to store runoff and sediment and <br />are often the last recourse to prevent downstream <br />flooding and sedimentation. They are often designed <br />to trap SO to 70 percent of the expected flows. No <br />estimates of sediment trapping efficiencies for debris <br />basins were found. <br />Road Treatments-Road treatments are designed <br />to move water to desired locations and prevent wash- <br />out of roads. There is little quantitative research <br />evaluating and comparing road treatment effective- <br />ness. Arecent computer model, X-DRAIN, can provide <br />sediment estimates for vari oua spacings of cross drains <br />(Elliot and others 1998), and the computer model, <br />WEPP-Road, provides sedimentation estimates for <br />variousroad configurationsand mitigation treatments <br />(Elliot and others 1999). Thus, effectiveness ofvarioua <br />spacings of rolling dips, waterbara, cross drains, and <br />culvert bypasses can be compared. By shortened flow <br />paths and route water at specified crossings, erosion <br />can be reduced. Upgrading culverts to larger sizes <br />increases their flow capacity, which reduces the risk of <br />blockage and exceeding capacity. Culvert armoring <br />and adding risers allow sediment to settle out and <br />prevent scouring. Trash racks prevent clogging of <br />culverts or other structures which keeps the culverts <br />opening as designed. Culvert removal, when appropri- <br />ate, eliminates the threat of blockage. Storm patrol <br />shows promise as a new coat effective method to keep <br />culverts and drainage ditches clear, provide early <br />warnings and close areas that could be threaten by a <br />storm flows. Armoring ford crossings allows for low- <br />coataccess across stream channels, with the ability to <br />handle large flows. Ditch cleaning and armoring pro- <br />vide for drainage of expected flows and reduce scour- <br />ing. Outaloping prevents concentrated flow on road <br />eurfaces thus reducing erosion. Detail discussion of <br />road related treatment effectiveness is beyond the <br />scope of this report. The recent USDA Forest Service, <br />San Dimas Technology and Development Program, <br />Water/RuadInteractionTechnologieaSeriea(Copstead <br />1997) provides design standards, improvement teeh- <br />niquea, and evaluations of some surface drainage <br />treatments for reducing sedimentation. <br />Gonclusions <br />Relatively little monitoring of BAER treatments <br />has been conducted in the last three decades. Pub- <br />liahedliterature focused on seeding issues, with little <br />information on any other treatments. Therefore, in- <br />terview forms and monitoring reports were used to <br />document our current knowledge on treatment op- <br />tionsand their effectiveness. There were at least 321 <br />BAER project tires during last three decades that <br />cost the Forest Service around $110 million to reha- <br />bilitate. Some level of monitoring occurred on about <br />33 percent of these project fires. Our analysis of the <br />literature, Burned Area Report forma, interview com- <br />ments, monitoring reports, and treatment effective- <br />ness ratings leads us to the following conclusions: <br />Existing effectiveness monitoring efforts and re- <br />aearchare insufficient to accuratelyoompare treat- <br />ment effectiveness and ecosystem recovery. <br />Rehabilitation should be done only if the risk to <br />life and property is high since the amount of <br />protection provided is assumed to be small. In <br />some watersheds, it would be beat not to do any <br />treatments. If treatments are necessary then it is <br />more effective to reduce erosion onaite (hfllslope <br />treatment) rather than collected it downstream <br />(channel treatment). <br />Contour-felled logs show promise as a relatively <br />effective treatment compared to other hillslope <br />treatments. This is considered to be true for areas <br />where erosion rates are expected to be high be- <br />cause they provide protection during the firet- <br />year postfirewhich has the highest erosion rates. <br />In areas that do not have available trees, straw <br />wattles may provide an alternative. however, the <br />effectiveneseofcontour-felledlogsoratrawwattlea <br />has not been adequately documented in the scien- <br />tific literature. <br />Seeding has a low probability of reducing erosion <br />the first wet season after a fire. There is a need to <br />do other treatments in critical areas. Seeding can <br />provide reasonable cover late in first season and <br />in the second year. Most estimates ofground cover <br />occur at the end of the first growing season, thus <br />cover information ie not appropriate for compari- <br />son for first year storm events. <br />There is a need to better understand regeneration <br />potential of natural vegetation. Seeding treat- <br />ment may not be needed as often as currently <br />thought. <br />Because seeding is often not "successful," it may <br />have little impact on natural regeneration. Per- <br />sistent perennials are least effective at providing <br />first year cover and moat likely to interfere with <br />later regeneration. Cereal grains (annuals) offer <br />better first-year protection than perennials but <br />generally do not interfere with later regeneration <br />of natural vegetation. Little is known about the <br />effectiveness of native annual grasses. <br />Evaluating poatfire watershed conditions, treat- <br />ment chance of success, coat-benefit ratios, and <br />USDA Forest Service Gen. Tech. Rep. RMRS-GTRE3. 2000 53 <br />
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