SSURGO Drainage Class, Soils, Santa Barbara County, California

Jul 14, 2016 (Last modified Jan 25, 2023)
Description:
Drainage class (natural)" refers to the frequency and duration of wet periods under conditions similar to those under which the soil formed. Alterations of the water regime by human activities, either through drainage or irrigation, are not a consideration unless they have significantly changed the morphology of the soil. Seven classes of natural soil drainage are recognized-excessively drained, somewhat excessively drained, well drained, moderately well drained, somewhat poorly drained, poorly drained, and very poorly drained.

The seven values of drainage class are defined by the NRCS Soil Survey Manual as:
  • Excessively drained: Water is removed very rapidly. The occurrence of internal free water commonly is very rare or very deep. The soils are commonly coarse-textured and have very high hydraulic conductivity or are very shallow.
  • Somewhat excessively drained: Water is removed from the soil rapidly. Internal free water occurrence commonly is very rare or very deep. The soils are commonly coarse-textured and have high saturated hydraulic conductivity or are very shallow.
  • Well drained: Water is removed from the soil readily but not rapidly. Internal free water occurrence commonly is deep or very deep; annual duration is not specified. Water is available to plants throughout most of the growing season in humid regions. Wetness does not inhibit growth of roots for significant periods during most growing seasons. The soils are mainly free of the deep to redoximorphic features that are related to wetness.
  • Moderately well drained: Water is removed from the soil somewhat slowly during some periods of the year. Internal free water occurrence commonly is moderately deep and transitory through permanent. The soils are wet for only a short time within the rooting depth during the growing season, but long enough that most mesophytic crops are affected. They commonly have a moderately low or lower saturated hydraulic conductivity in a layer within the upper 1 m, periodically receive high rainfall, or both.
  • Somewhat poorly drained: Water is removed slowly so that the soil is wet at a shallow depth for significant periods during the growing season. The occurrence of internal free water commonly is shallow to moderately deep and transitory to permanent. Wetness markedly restricts the growth of mesophytic crops, unless artificial drainage is provided. The soils commonly have one or more of the following characteristics: low or very low saturated hydraulic conductivity, a high water table, additional water from seepage, or nearly continuous rainfall.
  • Poorly drained: Water is removed so slowly that the soil is wet at shallow depths periodically during the growing season or remains wet for long periods. The occurrence of internal free water is shallow or very shallow and common or persistent. Free water is commonly at or near the surface long enough during the growing season so that most mesophytic crops cannot be grown, unless the soil is artificially drained. The soil, however, is not continuously wet directly below plow-depth. Free water at shallow depth is usually present. This water table is commonly the result of low or very low saturated hydraulic conductivity of nearly continuous rainfall, or of a combination of these.
  • Very poorly drained: Water is removed from the soil so slowly that free water remains at or very near the ground surface during much of the growing season. The occurrence of internal free water is very shallow and persistent or permanent. Unless the soil is artificially drained, most mesophytic crops cannot be grown. The soils are commonly level or depressed and frequently ponded. If rainfall is high or nearly continuous, slope gradients may be greater.

This dataset is from the USDA SSURGO soils database; the dataset was clipped by a buffered boundary of Santa Barbara County, California. The attribute is titled Drainage Class - Dominant Condition "drclasscd".

The entire dataset can be downloaded from the following website: http://websoilsurvey.sc.egov.usda.gov/App/HomePage.htm





Data Provided By:
United States Department of Agriculture Natural Resources Conservation Service

Content date:
January 2016
Citation:
Soil Survey Staff, Natural Resources Conservation Service, United States Department of Agriculture. Web Soil Survey. Available online at http://websoilsurvey.nrcs.usda.gov/
Contact Organization:
United States Department of Agriculture
Contact Person(s):
Use Constraints:
Creative Commons LicenseThis work is licensed under a Creative Commons Attribution 3.0 License.
Layer:
Layer Type:
Currently Visible Layer:
All Layer Options:
Layers in this dataset are based on combinations of the following options. You may choose from these options to select a specific layer on the map page.
Description:
Spatial Resolution:
Credits:
Citation:
Purpose:
Methods:
References:
Other Information:
Time Period:
Layer Accuracy:
Attribute Accuracy:
FGDC Standard Metadata XML
Click here to see the full FGDC XML file that was created in Data Basin for this layer.
Original Metadata XML
Click here to see the full XML file that was originally uploaded with this layer.
This dataset is visible to everyone
Dataset Type:
Layer Package
Downloaded by 1 Member
Bookmarked by 1 Member , 3 Groups
Included in 13 Public Maps , 8 Private Maps
Included in 3 Public Galleries

About the Uploader

Conservation Biology Institute

We provide advanced conservation science, technology, and planning to empower our partners in solving the world’s critical ecological challenges