<URL:http://water.usgs.gov/nawqa-only/gw.html>
This data set consists of area weighting factors for county/NLCDE land use for NAWQA LUS and SUS areas. The weighting factors can be used to apportion county-based chemical applications data to certain agricultural land use categories or population to residential land use categories.
This is one of the ancillary GIS data layers developed to characterize NAWQA ground water studies for national synthesis of water-quality data.
NLCDE LANDCOVER CODES AND DESCRIPTIONS ----------------------------------------------- 11 Open Water 12 Perennial Ice/Snow 21 Low-Intensity Residential 22 High-Intensity Residential 23 Commercial/Industrial/Transportation 25 Residential without trees (GIRAS) 26 Forested Residential (Residential from GIRAS, Forest from NLCD) 31 Bare Rock/Sand/Clay 32 Quarries/Strip Mines/Gravel Pits 33 Transitional 41 Deciduous Forest 42 Evergreen Forest 43 Mixed Forest 51 Shrubland 61 Orchards/Vineyards/Other 62 Orchards/Vineyards (from GIRAS) 71 Grasslands/Herbaceous 72 Tundra (from GIRAS) 81 Pasture/Hay 82 Row Crops 83 Small Grains 84 Fallow 85 Urban/Recreational Grasses 91 Woody Wetlands 92 Emergent Herbaceous Wetlands
The county/land use weighting factors were created by overlaying each ground water study area with the NLCDE land use and then overlaying the study area land use with county boundaries. The weighting factors show all combinations of county/land use comprising the ground water study area and what fraction of the ground water study each combination covers.
The weighting factors are used with county-based data chemical application data to apportion nutrients and pestcides by specific agricultural land use categories. The weighting factors also could be used to distribute population to residential land.
Using the county/land use weighting factors avoids doing multiple overlays of the study area, land use, and counties. Calculations can be done outside of the overlay processing environment using the weighting factors and other tabular data.
Here is an example of part of a county/land use weight table for acfbluscr2_trg showing the row crops/small grains/fallow weighting factor, which applies to NLCDE codes 82, 83, 84. Only NLCDE code 82 appears in the GW study.
COUNTY NLCDE
FIPS LAND USE AREAKM2 AREAF COUNTY_KM2 COUNTY_F CGF_KM2 CGF
13099 11 0.0891000 0.00055525 1337.1720 0.00006663 0.0000 0.00000000
13099 23 0.0081000 0.00005048 1337.1720 0.00000606 0.0000 0.00000000
13099 33 1.1331000 0.00706117 1337.1720 0.00084739 0.0000 0.00000000
13099 41 2.8854000 0.01798103 1337.1720 0.00215784 0.0000 0.00000000
13099 42 1.2870000 0.00802024 1337.1720 0.00096248 0.0000 0.00000000
13099 43 2.3931000 0.01491315 1337.1720 0.00178967 0.0000 0.00000000
13099 81 7.3809000 0.04599577 1337.1720 0.00551978 0.0000 0.00000000
13099 82 16.5375000 0.10305720 1337.1720 0.01236752 430.1496 0.03844593
13099 91 1.5255000 0.00950650 1337.1720 0.00114084 0.0000 0.00000000
13099 92 0.2619000 0.00163209 1337.1720 0.00019586 0.0000 0.00000000
13201 11 0.5058000 0.00315201 734.7132 0.00068843 0.0000 0.00000000
13201 23 0.0306000 0.00019069 734.7132 0.00004165 0.0000 0.00000000
13201 31 0.0072000 0.00004487 734.7132 0.00000980 0.0000 0.00000000
13201 33 2.9916000 0.01864284 734.7132 0.00407179 0.0000 0.00000000
13201 41 9.9459000 0.06198016 734.7132 0.01353712 0.0000 0.00000000
13201 42 4.8591000 0.03028060 734.7132 0.00661360 0.0000 0.00000000
13201 43 7.1163000 0.04434685 734.7132 0.00968582 0.0000 0.00000000
13201 81 22.8024000 0.14209840 734.7132 0.03103578 0.0000 0.00000000
13201 82 71.7273000 0.44698510 734.7132 0.09762625 327.8826 0.21875910
13201 85 0.0009000 0.00000561 734.7132 0.00000122 0.0000 0.00000000
13201 91 6.4764000 0.04035917 734.7132 0.00881487 0.0000 0.00000000
13201 92 0.5040000 0.00314079 734.7132 0.00068598 0.0000 0.00000000
______________ _______________
total = 160.47 total = 1.0
KM2
FIPS is the county code. Two counties occur in this particular
ground water study.
NLCDE is the NLCDE land use code.
AREAKM2 is the square kilometers of each county/land use combination in the
ground water study.
AREAF is the fraction of the ground water study represented by each
county/land use combination. (AREAF = AREAKM2/total AREAKM2 for GW study)
COUNTY_KM2 is the total square kilometers of a county.
COUNTY_F is the fraction of the county represented by each county/land use
combination. (COUNTY_F = AREAKM2/COUNTY_KM2)
CGF_KM2 is the total square kilometers of row crops+small grains+fallow
in the county.
CGF is the fraction of the county row crops+small grains+fallow
represented by county row crops/small grains/fallow in the GW study.
(CGF = AREA_KM2/CGF_KM2).
Applies only to land use categories 82, 83, and 84.
Processing routines are from the NAWQA area characterization
toolbox.
Used recalculated land use percents for several cycle 2 areas. For the previous calculations, the doughnut holes in the some of the study areas had not been removed in the gridded versions of the study areas. This affects seven study areas:
with doughnuts without doughnuts cut out (correct) not cut out (incorrect) AREAID GRID AREA (M2) GRID AREA (M2) cnbrluscr1_bnd 7,044,202,800.000 7,392,941,100.000 cnbrluscr1_trg 5,706,866,700.000 6,766,256,700.000 connlusrc1_bnd 1,756,677,600.000 2,064,634,200.000 connlusrc1_trg 587,594,700.000 610,191,000.000 connsus2_bnd 6,848,918,100.000 7,617,282,300.000 nvbrlusrc1_trg 155,431,800.000 155,443,500.000 spltluscr2_trg 207,267,300.000 228,433,500.000
Added studies that are resampled studies, but do not have the same boundaries in cycle 2 as were used in cycle 1:
albelusag1, nvbrsus2, trinsus3, sanjluscr1a, sanjlusor2a.
Added willlusag3, which has the same boundaries as cycle 1 willlusag2.
Deleted MANURE and MANURE_KM2 categories in both cycle 1 and cycle 2 files and replaced them with MANURE_CONF, MANURE_CONF_KM2, MANURE_UCONF, MANURE_UCONF_KM2. The previous NLCDE grouping for MANURE was 71, 81, 82, 83, 84 and we needed to break out confined (71, 81, 82, 83, 84) and unconfined (81, 82, 83, 84) manure instead of treating everything as one group.
The data set is referenced by SUCODE (NAWQA study unit/network code) and AREAID (ground water study boundary coverage). Two kinds of ground water network polygon coverages exist: 1) BND coverages, which represent the entire areal extent of the hydrogeologic unit defined for study, and 2) TRG coverages, which delineate the targeted land use within the BND.
The data set is organized by AREAID. Missing data is indicated by -9999.
The weighting factors for nutrients/pesticides apply only to land use codes listed in the table below. If a qualifying land use occurs in the GW study area the weighting factor is equal to the area of the qualifying NLCDE code in the part of the county within the GW study area divided by the total area of the land use group for the entire county.
Land use group NLCDE codes Purpose ------------------------------------------------------------------------------------------ CGF 82,83,84 allocating pesticides to row crops/small grains/fallow PAST 81 allocating pesticides to pasture/hay ORCH 61,62 allocating pesticides to orchards/vineyards ALLAG6 61,62,81,82,83,84 allocating nutrients (fertilizer) to farm lands (all 6 ag land types) *FARM 61,62,82,83 allocating nutrients (fertilizer) to farm lands *NO LONGER USED 9/29/04 NFARM 21,25,26,85 allocating nutrients (fertilizer) to non-farm lands MANURE_CONF 81,82,83,84 allocating nutrients (manure) to ag lands MANURE_UCONF 71,81,82,83,84 allocating nutrients (manure) to grasslands and ag landsFields in the weight table are:
SUID NAWQA study unit
SUCODE NAWQA study unit/network code
AREAID Ground water boundary coverage
COUNTYG (FIPS) County FIPS code (from CO1990G)
NLCDE (LUC) NLCDE land use code
AREAKM2 square kilometers of each county/land use combination within the GW study
AREAF fraction of the ground water study represented by each county/land use
combination
COUNTY_KM2 total square kilometers of a county (CO1990G)
COUNTY_F fraction of the county represented by each county/land use combination
FIPSLU unique combination of county code and land use code
CGF weighting factor for NLCDE row crops/small grains/fallow
(AREAKM2 of CGF/CGF_KM2)
CGF_KM2 square kilometers of row crops+small grains+fallow in the entire county
PAST weighting factor for NLCDE pasture (AREAKM2 of PAST/PAST_KM2)
PAST_KM2 square kilometers of pasture in the entire county
ORCH weighting factor for NLCDE orchards (AREAKM2 of ORCH/ORCH_KM2)
ORCH_KM2 square kilometers of orchards in the entire county
ALLAG6 weighting factor for NLCDE all agricultural categories (AREAKM2 of ALLAG6/ALLAG6_KM2)
ALLAG6_KM2 square kilometers of all agricultural categories in the entire county
NONF weighting factor for NLCDE non-farm land (AREAKM2 of NONF/NONF_KM2)
NONF_KM2 square kilometers of non-farm land in the entire county
MANURE_CONF weighting factor for NLCDE confined manure land (AREAKM2 of MANURE_CONF/MANURE_CONF_KM2)
MANURE_CONF_KM2 square kilometers of confined manure land in the entire county
MANURE_UCONF weighting factor for NLCDE unconfined manure land (AREAKM2 of MANURE_UCONF/MANURE_UCONF_KM2)
MANURE_UCONF_KM2 square kilometers of unconfined manure land in the entire county
These fields were removed in 2005. Use confined/unconfined manure categories.
MANURE weighting factor for NLCDE manure land (AREAKM2 of MANURE/MANURE_KM2) MANURE_KM2 square kilometers of manure land in the entire countyThese fields were removed in September 2006. Use ALLAG6 for farm fertilizer.
FARM weighting factor for NLCDE farm land (AREAKM2 of FARM/FARM_KM2) FARM_KM2 square kilometers of farm land in the entire county
kjhitt@usgs.gov
kjhitt@usgs.gov