Difference between revisions of "NLCD Land Cover"

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== Legend ==
 
== Legend ==
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[[image:NLCD_Colour_Classification_Update.jpg|right|thumb|NLCD2016 land cover classification legend from mrlc.gov]]
  
 
Use the -n and -c flags of d.legend to limit the legend to named categories.
 
Use the -n and -c flags of d.legend to limit the legend to named categories.

Revision as of 20:41, 1 July 2019

About

  • Raster grid covering the Continental US at 30 meter resoltion

Obtaining data from the USGS

The classic Spearfish GRASS sample dataset contains a landcover.30m raster map which is an excerpt from an older version of the NLCD dataset.

  • Data is provided in ERDAS Imagine .img format.
As of April 2019 the zipped dataset is a 1.4 GB.
  • Create an Albers location
this can also be done automatically with the Location Wizard using the downloaded .img file.

Here are the values for the CONUS dataset:

name: Albers Equal Area
proj: aea
datum: wgs84
ellps: wgs84
lat_1: 29.5
lat_2: 45.5
lat_0: 23
lon_0: -96
x_0: 0
y_0: 0
towgs84: 0,0,0,0,0,0,0
no_defs: defined
  • It is very large, connect to it with r.external then crop out the section you need with g.region and r.mapcalc.

Categories

These can be applied with the r.category module.

0:Unclassified
11:Open Water
12:Perennial Snow/Ice
21:Developed, Open Space
22:Developed, Low Intensity
23:Developed, Medium Intensity
24:Developed, High Intensity
31:Barren Land
41:Deciduous Forest
42:Evergreen Forest
43:Mixed Forest
52:Shrub/Scrub
71:Herbaceous
81:Hay/Pasture
82:Cultivated Crops
90:Woody Wetlands
95:Emergent Herbaceous Wetlands

Colors

These should load in automatically, but if they don't here are the official colors which you can load in with the r.colors module's rules= option:

11 70:107:159
12 209:222:248
21 222:197:197
22 217:146:130
23 235:0:0
24 171:0:0
31 179:172:159
41 104:171:95
42 28:95:44
43 181:197:143
52 204:184:121
71 223:223:194
81 220:217:57
82 171:108:40
90 184:217:235
95 108:159:184

Legend

NLCD2016 land cover classification legend from mrlc.gov

Use the -n and -c flags of d.legend to limit the legend to named categories.

Manning's n

For using as a basis for Manning's n friction coefficients, you can make a reclass map with r.reclass. The module will only reclass as integers so the table below is reclassed into parts per thousand. Crop your area of interest with r.mapcalc and divide by 1000.0 at the same time to get the Mannings n number.

TODO: values of 999 require values from the literature
0 = 0  Unclassified
11 = 999  Open Water
12 = 999  Perennial Snow/Ice
21 = 0404 Developed, Open Space
22 = 0678 Developed, Low Intensity
23 = 0678 Developed, Medium Intensity
24 = 0404 Developed, High Intensity
31 = 0113 Barren Land
41 = 3600 Deciduous Forest
42 = 3200 Evergreen Forest
43 = 4000 Mixed Forest
52 = 4000 Shrub/Scrub
71 = 3680 Herbaceous
81 = 3250 Hay/Pasture
82 = 999 Cultivated Crops
90 = 0860 Woody Wetlands
95 = 1825 Emergent Herbaceous Wetlands

See also