One of the advantages of the new RDBMS-based GIS is the possibility to include Time Series data inside the geodatabase. To accomplish this first you need to get familiar with the Arc Hydro Time Series tabular format and structure. A brief review of the Arc Hydro tabular structure for time series data is given below.

The Arc Hydro time series format requires one record for each single time stamp. Besides the ObjectID for each Time Series record, any Arc Hydro Time Series table is organized in a format that contains each single date/time value in a separate record/row as well as the date/time information, TSDateTime. The Arc Hydro time series format also requires all the recorded rainfall values in a single column called, TSValue.

• FeatureID: A unique identifier for each time stamp value.

• TSTypeID: A number defining what variable makes up the time series table, That is, 1 for gauged stream flow, 2 for gauged precipitation, 3 for radar precipitation, etc.

• TSDateTime: The time stamp for each record (the format follows the MS Access format for date and time)

• TSValue: The actual value of the variable for the corresponding time stamp.

Together with the Time Series table there is a TSType table that you will need to create and populate with fields that describe your time series data. This will be done later on so do not worry right now about this table and only try to understand its structure.

For future reference:

After you create the TSType table you must add it  to ArcMap and start the edit session to populate the TSType table with the following variables/fields. In order to populate the TSType table your geodatabase should already be formatted with the Arc Hydro Data Model (using the database schema) to get the proper domains for each field in this TSType table. This step will be done at the Phase: "Apply the Database Schema."

• ObjectID = 1

• TSTypeID = 3 (For radar precipitation, same as defined in TimeSeries table)

• Variable = NEXRAD Rainfall (A general description of your time series data)

• Units = Inches (The units of your time series variable)

• IsRegular = True (For regular time steps)

• TSInterval = 15Minute (The time step)

• DataType = Average (The type of measurement)

• Origin = Recorded (The form in which the variable was obtained)

Below there is a TSType table corresponding to the above TimeSeries table.

It is possible to include  any time series that you may have available from external sources as long as you transfer the data from the format it currently is into the Arc Hydro time series format. Also, and only for the U.S. you can automatically download and add Time Series data to your Arc Hydro dataset by downloading stream flow data from The USGS NWIS website using the customized CRWR NWIS tool.

For the USGS NWIS site go to: http://waterdata.usgs.gov/nwis/discharge

For the CRWR NWIS tool go to: http://civilu.ce.utexas.edu/stu/whiteatl/hydrotools.html

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