Talk:Arc Hydro Groundwater Data Model/Temp

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Time Series

The Time Series component provides a new design for dealing with temporal data within Arc Hydro. The new design provides better support for utilizing multiple representations of time series data and a new table to describe time series variables.

The TimeSeries table's purpose is to list [Time, Value] pairs.

TimeSeries
Field Type Description
FeatureID OID HydroID. Unique numerical identifier for the feature within the geodatabase.
VarID Integer Unique numerical identifier for the variable within the geodatabase.
TsTime Double The time stamp specifying the date and time associated with the time series value.
UTCOffset Double The number of hours the time coordinate system used to define TsTime is displaced from Universal Coordinate Time.
TsValue Double The numerical value itself.

The VariableDefinition table stores the description of temporal variables in a geodatabase, and a one-to-many relationship relates time series values with their description through the common VarID.

VariableDefinition
Field Type Description
VarID Integer Unique numerical identifier for the variable within the geodatabase.
VarKey Text Unique text ID for a variable, used when a variable is indexed in an attribute series table via field names.
VarName Text The name of the variable.
VarDesc Text The description of the variable.
VarUnits Text Units of measure for the variable.
Medium Text Medium in which the time series variable is observed or occurs, e.g., "Water".
VarCode Text Public identifier for a variable, e.g., "00060" for discharge in USGS NWIS.
Vocabulary Text The name of the list of variables in which a particular VarCode is defined.
TimeUnits Double For regular time series, the time unit used to describe the length of time between occurrences of a time series value.
TimeStep Double For regular time series, the number of TimeUnits between each occurrence of a time series value.
DataType Integer Describes whether the time series are instantaneous measurements, cumulative values, etc.
NoDataVal Double Numerical value used to indicate a "No Data Value" in the time series table.
IsRegular Integer True if the time series is regularly spaced in time. False otherwise.

However, often it is useful to see a list of all available time series at a glance. For this purpose, the Time Series component includes a SeriesCatalog table. Each row in the SeriesCatalog table indexes a time series in the TimeSeries table, and provides a summary of the time series including the variable described (e.g., water levels), the feature where the values were measured (e.g., well 6823302), the time period of the data, and the number of values in the series.

SeriesCatalog
Field Type Description
ObjectID OID Unique numerical identifier for the feature within the geodatabase.
SeriesID OID Unique numerical identifier for the time series.
FeatureID OID The HydroID of the feature.
FeatClass Text Feature class of the feature.
VarID Integer Unique numerical identifier for the variable within the geodatabase.
TsTable Text The name of the TimeSeries table.
StartTime Double The time stamp specifying the date and time associated with the start of the time series.
EndTime Double The time stamp specifying the date and time associated with the end of the time series.
ValueCount Integer The number of values in the time series.
GroupName Text

An attribute series is a tabular structure that supports archiving time series data where multiple variables are indexed with the same feature and time.

AttributeSeries
Field Type Description
FeatureID Integer HydroID. Unique numerical identifier for the feature within the geodatabase.
TsTime Double The time stamp specifying the date and time associated with the time series value.
VarKey1 Double Unique text ID for a variable, used when a variable is indexed in an attribute series table via field names.
VarKey2... Double

Feature series are collections of features indexed by time. Each feature in a feature series exists for only a period of time, making feature series an ideal structure for representing a series of geometries varying in location or shape.

FeatureSeries
Field Type Description
OBJECTID OID Unique numerical identifier for the feature within the geodatabase.
GroupID Integer Group identifier.
TsTime Double The time stamp specifying the date and time associated with the time series value.
VarID Integer Unique numerical identifier for the variable within the geodatabase.

The DatasetCatalog table indexes time series datasets within a geodatabase. Entries in the DatasetCatalog relate to time series datasets as a whole rather than an individual feature. The DatasetCatalog is typically associated with RasterSeries and FeatureSeries in your geodatabase. For example, one entry in the DatasetCatalog might indicate that groundwater levels are represented in the geodatabase as a raster series with X number of time steps.

DatasetCatalog
Field Type Description
VarID Integer VarID of the related variable in the VariableDefinition table.
DsType Integer Type of time series dataset described by this record in the table, e.g., Raster Series, Feature Series, Feature Layer.
DsSource Text Name of the time series dataset described by this record in the table.
TsTable Text Name of the time series table that contains the time series values, used in cases like water levels and concentrations where each well (a feature in a feature class) is associated with a time series of values stored in a separate table, or NEXRAD cell polygons, where each cell is associated with a time series of rainfall stored in a separate table.
StartTime Double Start date/time of the time series.
EndTime Double End date/time of the time series.
StepCount Integer Number of unique time steps in the time series (dataset).
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