GEODATASET NAME: NCA_K2A83 IDENTIFICATION INFORMATION Description: K factor (erodibility factor) estimated from Universal Soil Loss Equation (USLE) for the Northern California outer HUC boundary. Abstract: USLE K-factor coefficient times 100 for Northern 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@epamail.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, Northern California Data Browser. Date of metadata entry/update: 09/06/2001 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/nca/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 nca_ 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 nca_k2a83 Cell Size = 30.000 Data Type: Integer Number of Rows = 16666 Number of Values = 33 Number of Columns = 11301 Attribute Data (bytes) = 12 BOUNDARY STATISTICS Xmin = -653136.312 Minimum Value = 0.000 Xmax = -314106.312 Maximum Value = 48.000 Ymin = 4044266.250 Mean = 20.493 Ymax = 4544246.250 Standard Deviation = 5.498 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: nca_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.