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EM: Specific Conductivity, USA (EM-982)
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Expand AllEM Identity and Description
EM Identification
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EM ID
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EM-982 |
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EM Short Name
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Specific conductivity, USA |
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EM Full Name
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Specific Conductivity, USA |
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EM Source or Collection
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US EPA |
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EM Source Document ID
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460 |
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Document Author
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Olson, J.R., and S.M. Cormier |
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Document Year
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2019 |
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Document Title
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Modeling Spatial and Temporal Variation in Natural Background Specific Conductivity |
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Document Status
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Peer reviewed and published |
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Comments on Status
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Published journal manuscript |
Software and Access
| (https://edg.epa.gov/ metadata/catalog/main/home.page) | |
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Contact Name
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John Olson |
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Contact Address
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California State Univ. Monterey Bay, 100 Campus Center, Seaside CA 93955 |
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Contact Email
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joolson@csumb.edu |
EM Description
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Summary Description
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We developed a random forest model that predicts natural background specific conductivity (SC), a measure of total dissolved ions, for all stream segments in the contiguous United States at monthly time steps between the years 2001 to 2015. Models were trained using 11 796 observations made at 1785 minimally impaired stream segments and validated with observations from an additional 92 segments. Static predictors of SC included geology, soils, and vegetation parameters. Temporal predictors were related to climate and enabled the model to make predictions for different dates. The model explained 95% of the variation in SC among validation observations (mean absolute error = 29 μS/cm, Nash-Sutcliffe efficiency = 0.85). The model performed well across the period of interest but exhibited bias in Coastal Plain and Xeric regions (26 and 30%, respectively). National model predictions showed large spatial variation with the greatest SC predicted to occur in the desert southwest and plains. Model predictions also reflected changes at individual streams during drought. |
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Specific Policy or Decision Context Cited
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N/A |
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Biophysical Context
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Stream segment taken from StreamCat database |
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EM Scenario Drivers
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N/A |
EM Relationship to Other EMs or Applications
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Method Only, Application of Method or Model Run
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Method + Application |
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New or Pre-existing EM?
em.detail.newOrExistHelp
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New or revised model |
Related EMs (for example, other versions or derivations of this EM) described in ESML
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Document ID for related EM
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None |
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EM ID for related EM
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None |
EM Modeling Approach
EM Relationship to Time
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EM Temporal Extent
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2001-2015 |
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EM Time Dependence
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time-dependent |
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EM Time Reference (Future/Past)
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past time |
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EM Time Continuity
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discrete |
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EM Temporal Grain Size Value
em.detail.tempGrainSizeHelp
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3 |
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EM Temporal Grain Size Unit
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Month |
EM Spatial Extent
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Bounding Type
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Geopolitical |
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Spatial Extent Name
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Contiguous United States |
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Spatial Extent Area (Magnitude)
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>1,000,000 km^2 |
Spatial Distribution of Computations
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EM Spatial Distribution
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spatially distributed (in at least some cases) |
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Spatial Grain Type
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area, for pixel or radial feature |
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Spatial Grain Size
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3.1 km2 |
EM Structure and Computation Approach
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EM Computational Approach
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Analytic |
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EM Determinism
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deterministic |
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Statistical Estimation of EM
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Model Checking Procedures Used
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Model Calibration Reported?
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Yes |
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Model Goodness of Fit Reported?
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Yes |
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Goodness of Fit (metric| value | unit)
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Model Operational Validation Reported?
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Yes |
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Model Uncertainty Analysis Reported?
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No |
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Model Sensitivity Analysis Reported?
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Yes |
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Model Sensitivity Analysis Include Interactions?
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Yes |
EM Locations, Environments, Ecology
Location of EM Application
Terrestrial location (Classification hierarchy: Continent > Country > U.S. State [United States only])
em.detail.relationToSpaceTerrestrialHelp
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Marine location (Classification hierarchy: Realm > Region > Province > Ecoregion)
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| None |
Centroid Lat/Long (Decimal Degree)
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Centroid Latitude
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39.83 |
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Centroid Longitude
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98.58 |
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Centroid Datum
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WGS84 |
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Centroid Coordinates Status
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Estimated |
Environments and Scales Modeled
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EM Environmental Sub-Class
em.detail.emEnvironmentalSubclassHelp
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Rivers and Streams |
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Specific Environment Type
em.detail.specificEnvTypeHelp
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Stream segment |
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EM Ecological Scale
em.detail.ecoScaleHelp
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Ecological scale is finer than that of the Environmental Sub-class |
Scale and taxa of organisms modeled
Scale of differentiation of organisms modeled
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EM Organismal Scale
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Not applicable |
Taxonomic level and name of organisms or groups identified
taxonomyHelp
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| None Available |
EnviroAtlas URL
em.detail.enviroAtlasURLHelp
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| GAP Ecological Systems, Average Annual Precipitation, Average Annual Daily Potential Wind Energy |
EM Ecosystem Goods and Services (EGS) potentially modeled, by classification system
CICES v 4.3 - Common International Classification of Ecosystem Services (Section > Division > Group > Class)
em.detail.cicesHelp
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(Environmental Subclass > Ecological End-Product (EEP) > EEP Subclass > EEP Modifier)
fegs2Help
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EM Variable Names (and Units)
Predictor
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Intermediate
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Intermediate (Computed) Variables (and Units)
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None |
Response
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Observed Response Variables (and Units)
view details (1 variable)
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Computed Response Variables (and Units)
view details (1 variable)
em.detail.computedResponseHelp
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