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Revised Universal Soil Loss Equation (RUSLE)
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Guidelines for the use of the Revised Universal Soil Loss Equation (RUSLE),
version 1.06, on Mined Lands, Construction Sites, and Reclaimed Lands
A variety of human activities disturb the land surface of the earth, and thereby
alter natural erosion rates. Federal and State legislation mandate erosion control
and sediment containment from lands subjected to many activities, including mining,
construction, and reclamation. Effective erosion control and sediment containment
begin with the project-planning process. At this time, predisturbance rates of
soil loss and sediment discharge can be assessed, together with the rates that are likely
to occur during and following land disturbance. Then, several erosion-control and
sediment-containment strategies can be evaluated in terms of effectiveness and cost. The
results of these evaluations may be part of a required permit application.
The Revised Universal Soil Loss Equation (RUSLE) is a set of mathematical equations that
estimate average annual soil loss and sediment yield resulting from interrill and rill
erosion. It is derived from the theory of erosion processes, more than 10,000 plot-years
of data from natural rainfall plots, and numerous rainfall-simulation plots. RUSLE is an
exceptionally well-validated and documented equation. A strength of RUSLE is that it was
developed by a group of nationally-recognized scientists and soil conservationists who
had considerable experience with erosional processes. RUSLE retains the structure of its
predecessor, the Universal Soil Loss Equation (USLE).
RUSLE reflects the evolutionary development of erosion-prediction technology. For nearly
100 years, erosion data have been collected, analyzed, presented, and discussed in the
professional arenas of agricultural and civil engineers, agronomists, soil scientists,
geologists, hydrologists, and geomorphologists. The breadth and depth of these
scientific investigations allow confidence in the application of RUSLE for the estimation
of soil loss from mined lands, construction sites, and reclaimed lands.
RUSLE resulted from a 1985 workshop of government agency and university soil-erosion
scientists. The workshop participants concluded that the USLE should be updated to
incorporate the considerable amount of erosion information that had accumulated since
the publication of Agriculture Handbook 537 (in 1978) and to specifically address the
application of the USLE to land uses other than agriculture. This effort resulted in the
computerized technology of RUSLE as fully described in
Agriculture Handbook 703 (published in 1997).
The development of RUSLE included several USLE modifications of importance to mined
lands, construction sites, and reclaimed land applications. The climate data set in
the CITY files was greatly expanded to include weather bureau stations at many more
locations. The K (soil erodibility) factor was modified to account for the variability
of soil erodibility during the year. Both the K and C (cover management) factors now
take into account the multivariate influence of rock-fragment covers within soil profiles
and fragments resting upon hillslope surfaces. The equations used to estimate the LS
(hillslope length and steepness) factor were reconstituted to improve their accuracy and
extended to include steeper hillslope gradients than the equations contained in the USLE.
The method of determining C factor values was modified using a sub-factor approach that
incorporates input values describing the main features of a cover-management system as it
influences soil-loss rates. Consequently, RUSLE now can be applied to many more field
conditions, and provides much more site-specific C values than does the USLE. New
process-based equations were developed to estimate P (support practice) values,
overcoming a major limitation of the USLE. These equations accommodate a wide range of
site-specific practice conditions and can estimate sediment yield for concave hillslopes.
Collectively, every factor included in the USLE and its supporting data was reexamined in
the development of RUSLE. The new information compiled since 1978 was analyzed in the
development of RUSLE. In every way, RUSLE is an improved erosion-estimation technology.
Although perhaps convenient, the USLE no longer should be used for soil-loss
estimation, as RUSLE estimates better reflect the actual field conditions.
In 1997, the Office of Technology Transfer (OTT), Western Regional Coordinating Center
(WRCC), Office of Surface Mining, U.S. Department of Interior, assembled a working group
to examine the appropriate utilization of the RUSLE technology for the estimation of
soil-losses from mined land, construction sites, and reclaimed lands. OTT chose the
members of the working group to include persons experienced in: (1) the development and
use of RUSLE, (2) the site conditions and erosion processes resulting from mining,
construction, and reclamation activities, (3) research pertaining to, and measurement of,
these processes, and (4) the regulation of these activities. Each representative in the
working group was encouraged to communicate extensively with colleagues and associates to
gain broad insights into the germane issues, and to identify available information
sources.
The fundamental question asked was whether or not the site conditions resulting from
mining, construction, and reclamation activities can be accommodated within the RUSLE
technology. Accordingly, the working group examined each RUSLE factor carefully in
relation to the surface characteristics produced by these activities. For example,
the group compared the processes by which precipitation produces rainsplash, runoff,
and erosion from agricultural, mining, construction, and reclamation activities.
It also assessed the validity of the nomograph approach for estimating the K
values of topsoils that have been salvaged, stockpiled, redistributed, and developed
into a seedbed. The group considered the use of the nomograph for estimating the K
values of very coarse-textured "mine soil," "growth medium," or "soil substitutes."
It evaluated the validity of the tables for estimating the LS factor
of long and steep hillslopes, as sometimes proposed for site reclamation, and appraised
the validity of the subfactor approach for estimating C values. The group considered
appropriate C values for native-plant species and various mulches of natural and
artificial materials. It compared the effects of management and support practices
used on agricultural, mined, construction, and reclaimed lands. In short, OTT's
working group made a determined effort to characterize the special site conditions
resulting from mining, construction, and reclamation activities and to critically
examine the extent to which these conditions are accommodated within the RUSLE technology.
The Guidelines for the Use of the Revised Universal Soil Loss Equation, Version 1.06, on Mined
Lands, Construction Sites, and Reclaimed Lands represent the conclusions and recommendations of
OTT's working group. The guidelines were developed following a review of the available research
reports, the reassessment of the available data, and extensive discussions of the RUSLE technology,
from both general and factor-specific perspectives, based upon the experiences of the working group
members. Resources did not permit validation or calibration of the RUSLE model on mined lands,
construction sites, and reclaimed lands. However, the working group is confident that the guidelines
support the best use of the RUSLE technology as it currently exists. Future research will further
enhance the utilization of RUSLE on mined lands, construction sites, and reclaimed lands.
The guidelines and the RUSLE, Version 1.06, technology they describe provide direction for
maximizing the accuracy of RUSLE soil-loss estimates on mined lands, construction sites, and
reclaimed lands. RUSLE, Version 1.06, is a tool to estimate the rate of soil loss based on site-specific
environmental conditions and then to select and design sediment- and erosion-control systems for these
conditions. RUSLE, Version 1.06, does not determine when soil loss is excessive at a site or when
erosion-control systems have failed. The Version 1.06 user makes such decisions based upon
numerous criteria, of which soil-loss and sediment-yield estimates are one important component.
RUSLE, Version 1.06, is a technology for estimating soil loss from most undisturbed lands experiencing
overland flow, from lands undergoing disturbance, and from newly or established reclaimed lands.
Version 1.06 may also be used as a part of the procedures to prepare permit applications and to assess
reclamation success in support of bond release.
Typically, RUSLE, Version 1.06, is used to estimate the severity of soil loss and sediment yield from
disturbed-land surfaces and to select appropriate on-site erosion-control strategies. These strategies
are designed to protect soil resources so that their quality and quantity are maintained over the long-
term, to provide short-term erosion control while the long-term erosion-control measures become
established, and to minimize off-site sediment discharges into streams and reservoirs. Version 1.06
may be used as a part of the procedures to assess long-term reclamation success. It is a very powerful
tool that can be used to estimate soil loss under a wide variety of site-specific conditions. All models or
equations developed to estimate the rates of geomorphic processes, including RUSLE, Version 1.06,
possess limitations. It is important to respect these limitations.
These guidelines are based upon the premise that RUSLE, Version 1.06, will be used for estimating soil
loss from mined lands, construction sites, and reclaimed lands during future years, just as the USLE was
used in the past. It is the intention of the guidelines to: (1) provide guidance for maximizing the accuracy
of soil-loss estimates from mined lands, construction sites, and reclaimed lands when using Version
1.06, (2) recommend procedures so that soil-loss estimates are generally reproducible, and (3) identify
critical areas for future research. The recommended field and laboratory procedures for the acquisition
of RUSLE-input data from mined lands, construction sites, and reclaimed lands are intended to
supplement the directives contained in Agricultural Handbook 703.
The guidelines are divided into two parts. The first part is a discussion of each RUSLE,
Version 1.06, factor in relation to mined lands, construction sites, and reclaimed lands.
The concepts underlying each factor, the specific issues pertaining to lands disturbed
by the aforementioned activities, the recommended field and laboratory methods, as well
as other relevant information, is presented. The intent is to provide a background for
the prudent use of RUSLE. The second part is a discussion of Version 1.06 applications
for soil-loss estimates on mined lands, construction sites, and reclaimed lands. Research
design, organization of data inputs, interpretation and use of soil-loss estimates for
erosion-control planning, and limitations of the RUSLE technology are presented by means
of examples. The intent is to demonstrate the proper procedures for maximizing the
accuracy and reproducibility of RUSLE soil-loss estimates, thereby minimizing the misuse
of RUSLE.
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