ACCESSING AND USING STATEWIDE AGGREGATED SOIL SURVEY DATA
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Transcript of ACCESSING AND USING STATEWIDE AGGREGATED SOIL SURVEY DATA
CUSTOM QUERIES FOR SOIL DATA
http://sdmdataaccess.nrcs.usda.gov/
Outline
Basic Soil Data Concepts Aggregation “Traditional” Soil Survey Products Soil Data Access
Soil Survey Manual
Challenges to Spatially Displaying Soils Data The SSURGO soil database has multiple “one
to many relationships”.
Most map units have more than one component, especially when minor components are included.
Most components have multiple horizons.
○ Horizons can contain many different kinds and sizes of fragments
Ultimately need to come to one value for the map unit.
So, I want a map of the soil erodibilty factor (Kf)………….
0.020.020.020.020.020.020.1
0.150.150.150.150.170.170.170.170.170.280.280.32
Or a map of the T (tolerable soil loss) Factor…...
Aggregation Options..
Dominant Component: Returns the value of the component that comprises the highest percentage of the unit.
Aggregation Options..
Dominant Condition: Components are grouped by “condition” and the “condition” with the highest sum percentage is reported
T %5 354 40
Aggregation Options..
Most Limiting Condition: The most limiting “condition” is reported
Soil Data Mart
Houses the Official Soil Survey Data All products discussed get their data
from the Soil Data Mart
Web Soil SurveyInteractive Mapping Service that hosts soils
data and other basic GIS layersHas a good interface for aggregating soil
properties and
interpretationsLimited to 10,000
acre Area of InterestReal time access to
SDM data
“Traditional” Soil Survey Products
Soil Data Viewer Free ArcGIS extension (not programmed
for ArcGIS 10 yet ) Uses SSURGO spatial and tabular data
from the Soil Data Mart Great for single county datasets or small
groups of counties. Good, but limited
aggregation soil properties
Access Template for Tabular Data Tabular data from the Data mart is
imported into Great for creating custom queries
The New Kid on the Block…Soil Data Access
Provides access to the spatial and tabular aspects of the Soil Data Mart by means that are not being met by the WSS and the SDM
Is essentially a suite of Web Services This presentation will focus on the tabular
aspects and querying for custom data.
http://sdmdataaccess.nrcs.usda.gov/
Wisconsin’s approach to providing access to data using the Soil Data Access Site
Create queries that would return statewide aggregated soil propertiesFrom the official data
Document the properties returned and the aggregation methods used
Publish the queries and methodology. Updating regularly based on USER input and requestshttp://www.wi.nrcs.usda.gov/technical/soil/
soils_products.htm Include “mukey” as both a text field and as a number
Why MUKEY and not MUSYM?
Querying the Database
Standard SQL statements Select, From, where, order by.
Can select into temp tables A good understanding of the database
structure is needed (http://sdmdataaccess.nrcs.usda.gov/documents/TableRelationshipsDiagram.pdf)
Outer Joins are defined as Left or Right Joins
The SSURGO metadata is a great resource
SSURGO Metadata http://soildatamart.nrcs.usda.gov/SSURGOMetadata.aspx
Pre-Packaged Aggregated Attributes
Data elements in the Mapunit table Data elements in the MUAGGATT table
Try not to use the hydclprs field…
SELECT mu.musym, mu.muname, mu.mukind, mu.farmlndcl, mu.mukey,
cast (mu.mukey as int) as mukey_num
FROM sacatalog sac
INNER JOIN legend l ON l.areasymbol = sac.areasymbol and l.areasymbol LIKE 'WI%'
INNER JOIN mapunit mu ON mu.lkey = l.lkey
ORDER BY l.areasymbol, mu.museq