Southern
California Soils K Metadata
GEODATASET NAME: SCA_K2A83
IDENTIFICATION INFORMATION
Description:
K factor (erodibility factor) estimated from Universal Soil Loss
Equation (USLE) for the Southern California outer HUC boundary.
Abstract:
USLE K-factor coefficient times 100 for Southern California outer
HUC boundary, as estimated from STATSGO soil map unit coverage, USLE
Handbook, and other sources.
Data Type:
Grid
Raw Data Originator:
USDA Natural Resources Conservation Service
National Cartography and GIS Center
P.O. Box 6567
Fort Worth, TX 76115-0567
(817)334-5559
and
Rick Van Remortel
Lockheed Martin Environmental Services
1050 E. Flamingo Road, Suite E120
Las Vegas, NV 89119
(702)897-3295
rvanremo@lmepo.com
Data Processor:
Rick Van Remortel
Lockheed Martin Environmental Services
1050 E. Flamingo Road, Suite E120
Las Vegas, NV 89119
(702)897-3295
rvanremo@lmepo.com
Data Provider:
Dan Heggem
U.S. Environmental Protection Agency NERL
P.O. Box 93478
Las Vegas, NV 89193-3478
(702)798-2278
heggem.daniel@epa.gov
Keywords:
watershed, soils, water quality, USLE, erosion, sedimentation, K factor
Version:
N/A
Status:
Interim
Revision Number:
0
Series Name:
Online Link (URL):
Time Period of Content:
From Dec. 1994 revision
Use Constraints:
This grid contains uncertainty specific to a given location on a landscape,
so users should exercise caution when applying results to local situations.
The K-factor grid values were developed by area-weighting the individual
STATSGO soil components within a series of soil map units delineated within
the portion of the study area within a state, then joining multiple states
to a subregion level. STATSGO is a state-level database and, as such, the
specific K-factor value of a given point on the landscape cannot be known
with certainty because the distribution of soil components within each map
unit is variable across a state. Finer resolution data can be derived from
the SSURGO database (for soil survey areas) where such data have been
released by NRCS. However, SSURGO data only has improved resolution and
still is not point-specific. Caution must be exercised with the
interpretations drawn from STATSGO and SSURGO applications. The present
version of this grid should be considered Draft, for internal use only at
this time. The RUSLE K-factor data are best used for qualitative analysis
at landscape scales.
Purpose:
Regional erosion modeling in GIS, Southern California Data Browser.
Date of metadata entry/update:
1/22/2002
No Publication Information Available
No File Security Information Available
DATA QUALITY INFORMATION
Cloud Cover:
Not applicable
Software:
Arc/Info 7.2.1 Patch 2
Operating System:
Unix Sun Solaris 2.7
Path Name:
/gis/wemap/sca/soil
Logical Consistency Report:
Not presently available
Completeness Report:
Not presently available
Horizontal Positional Accuracy:
Not presently available
Vertical Positional Accuracy:
Not presently available
Attribute Accuracy:
Not presently available
Procedures:
This K-factor grid is one of five USLE-factor grids that are multiplied
together and divided by a grand expansion coefficient to calculate the
A value of estimated soil erosion. Due to file size considerations, the
K-factor grid was modified from the customary floating point format to an
integer grid. As a result, the grid carries an expansion coefficient of
100 that must be applied as a denominator to the data set to place the
factor in its proper units. For example, a K factor of '0.32' became a
grid value of '32' (expansion coefficient = 100, power-of-10 exponent = 2).
The K-factor values were derived from area-weighted STATSGO state-level
surface horizon soils data. The study area boundary grid was used as a
mask during this process. The basic procedure for calculating USLE was
developed by Weischmeier and Smith (1968) and augmented by Renard et al.
(1997) for RUSLE. See additional metadata provided below and the metadata
files attached to the A-value grid or other USLE or RUSLE factor grids
for more information.
Reviews Applied to Data
Lockheed Martin Environmental Services internal review
Related Spatial Data Files:
All geodatasets with sca_ or _k2_ root.
Other References Cited:
Renard, K.G., G.R. Foster, G.A. Weesies, D.K. McCool, and D.C. Yoder.
1997. Predicting soil erosion by water: A guide to conservation
planning with the Revised Universal Soil Loss Equation (RUSLE).
Agriculture Handbook No. 703. U.S. Dept. Agr., Agric. Res. Serv.
Wischmeier, W.H., and D.D. Smith. 1968. Predicting Rainfall Erosion
Losses: A Guide to Conservation Planning. USDA Handbook No. 537.
U.S. Department of Agriculture, Washington, DC.
Notes:
Update Frequency:
As needed
SPATIAL REFERENCE INFORMATION
Description of Grid sca_k2a83
Cell Size = 30.000 Data Type: Integer
Number of Rows = 10228 Number of Values = 27
Number of Columns = 14816 Attribute Data (bytes) = 12
BOUNDARY STATISTICS
Xmin = -361014.312 Minimum Value = 0.000
Xmax = 83465.688 Maximum Value = 38.000
Ymin = 3351865.000 Mean = 20.320
Ymax = 3658705.000 Standard Deviation = 6.499
COORDINATE SYSTEM DESCRIPTION
Projection ALBERS
Datum NAD83
Units METERS Spheroid GRS1980
Parameters:
1st standard parallel 33 15 0.000
2nd standard parallel 40 15 0.000
central meridian -116 45 0.00
latitude of projection's origin 0 0 0.000
false easting (meters) 0.00000
false northing (meters) 0.00000
ENTITY AND ATTRIBUTE INFORMATION
Annotation Name:
ATTRIBUTE LISTING FOR: sca_k2a83.vat
COLUMN ITEM NAME WIDTH OUTPUT TYPE N.DEC ALTERNATE NAME INDEXED?
1 VALUE 4 10 B - Indexed
5 COUNT 4 10 B - -
9 K_FACTOR 4 4 N 2 -
METADATA REFERENCE SECTION
FGDC Content Standards for Digital Geospatial Metadata
FGDC Standards Version 6/98 / metadata.aml ver. 1.3 5/21/99
SUPPLEMENTAL METADATA (where available)
Abstract:
The Universal Soil Loss Equation (USLE) and its derivative the
Revised (RUSLE) model are designed to predict
long-term average annual soil loss. USLE was developed primarily for
agricultural situations, but revisions for RUSLE have been more widely
applied. The equation is based on the concept that rainfall patterns
across a region set up characteristic erosion conditions that are
mitigated or exacerbated by soil type, slope, and land cover conditions.
The basic equation is: A = R * K * LS * C * P
where A is long-term average annual soil loss (tons/acre/year), R is
the rainfall erosivity factor, K is the soil erodibility factor, LS is
the length-slope factor, C is cover and management factor, and P is
the support management factor (e.g., strip cropping, buffer-strip
cropping). Over the eastern U.S. R ranges between 75 and 450, and
the other factors typically range between 0 and 1. Conceptually, USLE
estimates soil erosion as a reduction in potential erosion from rainfall
due to soil, slope, and land cover characteristics. RUSLE is a more
recent derivative of USLE that can be used in a wider range of topographic
and land use settings.
Soil erodibility factors (K) are estimated as part of the Natural
Resources Conservation Service (NRCS) digital STATSGO soils data base.
The basic map units of STATSGO soils are associated phases of soils
series. Each soil series typically has a unique K factor. The K factor
for each map unit was calculated as a weighted average across map unit
components.
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