Introduction to GIS

Lecture 18:Public Data 2: Other Public Data

Sources

Lecture notes by Austin Troy, University of Vermont © 2006

------Using GIS--

Introduction to GIS

• Comes from both the USGS and the EPA• Surface water features: lakes, ponds,

streams, rivers, springs• Nationally consistent• Order of linkages coded to allow for flow

path analysis• Background info at

http://nhd.usgs.gov/techref.html• Resolutions from 1:100k to 1:24k

National Hydrography Dataset (NHD)

Introduction to GIS

NHD• Many analysis tools designed for this data. For

instance: can find the path upstream or downstream from any point using NHD data and network analyst; flow reaches are numbered sequentially in order of flow to allow path analysis

• Stream reaches encoded like addresses on a street

• Connections encoded using topology• Other tools available at

http://nhd.usgs.gov/tools.html

Introduction to GIS

NHD

• Download at http://nhd.usgs.gov/tools.html

Introduction to GIS

NHD

• Can extract by County/state.

• Click on radio button of geography for clip

• Use check marks to make layers visible in base map

• Then Click on clip boundary (e.g. Chittenden County) in the map viewer

Introduction to GIS

NHD

• Can then choose the resolution and the database type

• Must turn popup blocker off to use

• Then get an email for custom download

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NHD

• Contents of Geodatabase: many feature classes with different purposes

Introduction to GIS

USDA Data

• USDA houses a number of data layers at their new Geospatial data gateway

• http://datagateway.nrcs.usda.gov/

Introduction to GIS

USDA Gateway Includes

• CLU farm boundaries

• Hydrologic Units (8 and 12 digit)

• Digital Raster Graphics

• High resolution color orthophotos from 2003-2004 (National Agriculatural Imagery Program)

• NRCS Soils data and soils tables

• Climate Data (precipitation and temp)

Introduction to GIS

USDA Gateway Includes

Introduction to GIS

USDA Gateway Includes

• Can Define clip regions by state or county

• Can also highlight a layer and get information

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Common Land Units

• Farm field boundaries representing smallest contiguous unit of cultivated land

• For farms in USDA programs

• Much more accurate that “agriculture” category in NLCD land cover

• Type of crop is unknown

Introduction to GIS

NAIP

• National Agricultural Imagery Program

• Digital Imagery, mosaiced by county, used by the NRCS and FSA to look at compliance with subsidy programs

• Ortho-rectified,• Color, 1:40,000 scale• 2003 and 2004

Introduction to GIS

SSURGO Soils Data• SSURGO: Soil Survey Geographic

Data from NRCS• Soils data also at

http://soildatamart.nrcs.usda.gov/Default.aspx

• Metadata and standards available at http://soildatamart.nrcs.usda.gov/SSURGOMetadata.aspx

• Entails both a polygon layer showing soils area boundaries, but also an Access Database of numerous soil attributes

Introduction to GIS

National Wetlands Inventory• From Fish and Wildlife Service• Maps all class 1 and 2 major wetlands• Available digitally for much of the country• 1:24,000 or smaller• Involves a complex taxonomy of wetlands

codes available at http://nwi.fws.gov/MapCodesLegend.pdf

• Includes marine, estuarine, riverine, lacustrine and palustrine types

Introduction to GIS

NWI• Wetlands map interface at

http://wetlandsfws.er.usgs.gov/wtlnds/launch.html• Allows you to view online data and download• First shows status availability map:

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NWI• Can make PDFs easily

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NWI• NWI by wetland type overlaid on NHD streams layer

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SSURGO• Soil Data Mart interface

• Access—sample tables; there are dozens

Introduction to GIS

Topologically Integrated Geographic Encoding and Reference System

Automates the mapping and related geographic activities required to support the decennial census and sample survey programs of the census bureau starting with the 1990 decennial census.

The Census TIGER® system supports:Creation and maintenance of the digital geographic data base that includes complete coverage of the United States and its territories

TIGER

Introduction to GIS

The TIGER system provides support for:

• Creation and maintenance of a nation wide digitalgeographic data base

• Production of maps from the TIGER® data base for allCensus Bureau enumeration and publication programs

• Allows for address geocoding

•Can be integrated with Census attribute databases easily

Introduction to GIS

Accuracy and Attribution:

•TIGER has good attribution, but poor accuracy

•They are based partially on 1:100,000 DLG

•Are often conflated

•This is often used to assign the attributes from TIGER® data to 1:24,000 DLG data

Introduction to GIS

The TIGER files contain data describing three feature types: •Line Features 1.Roads 2.Railroads 3.Hydrography 4.Transportation and Utility Lines•Boundary Features 1.Statistical boundaries, such as census tracts and blocks 2.Local government boundaries, such as places and counties 3.Administrative boundaries, such as congressional and school districts •Landmark Features 1.Point landmarks, such as schools and churches 2.Area landmarks, such as parks and cemeteries 3.Key geographic locations, such as apartment buildings and factories

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TIGER line files and the demographic filesDirect linkage using keys built up from:

State FIPS code

County FIPS code

Tract number

Block group number

Block number

Introduction to GIS

Best sources ESRI:http://www.esri.com/data/download/census2000_tigerline/index.html

Download 2000 U.S. Census TIGER lines files and demographic data

Other Sources: UC Davis government data server:http://www.lib.ucdavis.edu/govdoc/MapCollection/tiger.htmlOr UC Berkeley Tiger Server:http://sunsite.Berkeley.EDU/GovData/info/tiger.html

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©2006 Austin Troy

Introduction to GISIntroduction to GIS

©2006 Austin Troy

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For continuing data updates, check the data links page at http://www.uvm.edu/~nr143/supplement.html

Here you’ll find links to many state level GIS online data repositories plus many of the ones mentioned here

Another link is to map a network drive to \\zoofiles\gisdata

where you’ll find: NAIP imagery, ortho photos, all VCGI data plus VTrans database, World data from ESRI, DRG topo maps, Street maps USA

Introduction to GIS

Other sources for USGS data• www.mapmart.com

– Allows users to choose tiles and layers with a geographic interface

– Most public data are free, but ,any others available for a price

– Gives status maps– Can also buy bulk public data for a fee

• www.gisdatadepot.com– Not as user friendly– Just a plain old interface that is hard to navigate– However, many free data layers and lots of scripts and

extensions

Introduction to GIS

VCGI• The web

site offers many layers through a browser

Introduction to GIS

• Includes an interactive map browser for “clipping and zipping” data