Table of Contents

• What is Arc Hydro USA?
• Where did the data come from?
• How was Arc Hydro USA prepared?
• How can Arc Hydro USA be used?
  • To trace the flow path upstream and downstream of a selected point on the hydro network
  • To select the upstream and downstream watersheds
  • To provide data for analysis with Microsoft Excel

Download ArcHydroUSA.zip  (250 MB compressed, 760 MB uncompressed)

What is Arc Hydro USA?

Arc Hydro USA is an implementation of the ArcGIS Hydro Data Model for the continental United States.  It is a geodatabase containing a completely connected network of river reaches.  The fundamental purpose of Arc Hydro USA is to provide an example of how the Arc Hydro Data Model can be used to create a geodatabase in a consistent format from publicly available data, and to provide relationships between different features (or layers) within a geodatabase (a relationship -- or link -- between a watershed and its outlet point, for example).  Once the geodatabase is in this consistent format, the tools with the ArcHydro Toolset, and in the future other external models, can use a Arc Hydro geodatabase as input for hydrologic modeling.  

Where did the data come from?

Arc Hydro USA includes five datasets obtained from governmental sources (USGS and EPA) via the Internet:   

1.) HydroEdge from an extended version of U.S. EPA Reach File 1 (RF1)  http://water.usgs.gov/GIS/metadata/usgswrd/erf1.html

A line feature class of the major rivers in the continental United States click here for image

2.) Waterbody from a National Weather Service version of RF1   http://www.nohrsc.nws.gov/98/html/gisdata.htm

A polygon feature class of the lakes and reservoirs in the continental United States click here for image

3.) Watersheds from 8-digit Hydrologic Unit Code (HUC)  http://water.usgs.gov/GIS/huc.html

A polygon feature class of the drainage areas as defined by the 8-digit HUCs click here for image

4.) MonitoringPoints from the National Streamflow Information Program (NSIP)  http://water.usgs.gov/osw/programs/nsip/

A point feature class containing a complete record of active (6,375), inactive (11,523), other agencies (908), and non-real time (10) stream flow gages (Total of 18,827 gages). It also contains a subset of the USGS operated stream flow gages (1,596 of the 6,375 active gages) from the Hydro-Climatic Data Network (HCDN) Stream flow Data Set, 1874-1988, available on CD-ROM, (http://water.usgs.gov/GIS/metadata/usgswrd/hcdn.html), It provides stream flow records which meet strict quality control criteria. The subset of stations from the Hydro Climatic Data Network (1,596 HCDN gages) has Time Series available for the period Oct., 1988 through Sept, 2000 downloaded from the NWIS website. click here for image

5.) TimeSeries for each monitoring point in the HCDN network (Oct. 1988 - Sept 2000) from National Water Information System (NWIS). http://waterdata.usgs.gov/nwis

A object class (table) of stream flow time series data for each point in the Hydro-Climatic Data Network (HCDN) within the MonitoringPoints feature class over the period of October 1988 to September 2000. Note that this data was not obtained from the HCDN Streamflow Data Set, but rather was downloaded from the NWIS website. The data set provides an extension to the HCDN Stream flow Data Set, beginning where it left off (Sept, 1988) but has not been screened to comply with the HCDN quality control criteria. click here for image

Each dataset was added to the Arc Hydro Data Model as a feature class.  One addition feature class, generated by researchers at CRWR, was also included in Arc Hydro USA:  HydroJunction.  The HydroJunction feature class is necessary to establish relationships between features and the hydro network.  There are three scenarios where the creation of a Hydro Junction was necessary.  

1.)  To relate MonitoringPoints and HydroEdge.  It is often the case that the monitoring points do not fall directly onto the river reaches.  To link the HydroEdge network with the monitoring points, additional junctions on the HydroEdge feature class were created as a liaison between the MointoringPoints Feature class and the HydroEdge feature class.  

2.)  To relate Watersheds and HydroEdge.  It is important to include a junction at the outlet of each watershed to summarize and store characteristics about the watershed within the network conductivity.

3.)  To relate WaterBody and HydroEdge.  Likewise, it is convenient to include a network junction at the outlet of each water body to account for the behavior of the water body in network analysis.

 Thus, there are five geospatial feature classes within Arc Hydro USA ( HydroEdge, WaterBody, Watersheds, Monitoring Points, and HydroJunction) and one temporal feature dataset (TimeSeries).

How was Arc Hydro USA prepared?

The first step in preparing Arc Hydro USA for implementation into the Arc Hydro Data Model was to create a geodatabase containing six datasets mentioned above.  Secondly, on the Arc Hydro Toolset within ArcMap, the Hydro Network Generation tool (under the menu Network Tools), was used to build the river network, thus providing the necessary connectivity among the HydroEdge and HydroJunction feature classes.  Once the network was built and functioning properly (i.e. there were no broken links between junctions and edges) it was possible to apply the Arc Hydro Data Model schema to the geodatabase.  Appling the schema transformed the present geodatabase into an Arc Hydro Data Model geodatabse by creating the proper field names for each feature class and providing the relationships between the different feature classes (i.e. Watershed has HydroJunction, WaterBody has HydroJunction, MonitoringPoint has HydroJuction, etc.)  The final step was to populate the attributes for each feature class within the geodatabase.  The ArcHydro Toolset has tools to do just this, contained within the menu Attribute Tools.  Once the attributes for the feature classes were populated, Arc Hydro USA was complete.  

How can Arc Hydro USA be used?

Again, the fundamental purpose of Arc Hydro USA is to provide a consistent and uniform method for storing geospatial and temporal data for water resources analysis.  Thus, Arc Hydro USA is an open framework, providing consistent data to feed models.  That said, there are a number of important tools within he Arc Hydro Toolset (available for download here) that demonstrate the visual and computational capacities possible with GIS Hydrology.  One tool in particular, Trace Upstream/Downstream, is demonstrated here.

Trace Downstream/Upstream on Network

Arc Hydro USA provides a complete stream network for the continental United States.  This means that we can find the flow path from any point in the US to the gulf or ocean to which it drains.  These few steps show how to trace the upstream or downstream path from a selected point.

1.)  Add the Utility Network Analyst toolbar under the View menu in ArcGIS.  

2.)  On the Utility Network Analyst toolbar, select to trace the HydroNetwork downstream.

3.)  Now click the flag button on the toolbar and place the anywhere on the map by clicking on a location.  You should see a green square at the location you clicked.  This represents the flag.

4.)  Press the button to perform the trace.  The red line represents the flow path on the HydroNetwork downstream of the flag.  

 

5.)  It is also possible to trace the upstream path along the HydroNetwork.  To do so, simply change the Trace Task on the toolbar from Trace Downstream to Trace Upstream.

6.)  After a few traces, things might get messy.  You can clear trace paths and flags by selecting the option under the Analysis menu on the Utility Network Analysis toolbar.  

 Select Downstream/Upstream Watersheds

The Trace Downstream/Upstream tool on the Arc Hydro Toolset  allows the user to select a HydroJunction or Watershed feature, and to trace the upstream or downstream (or both) path of water flow through that particular feature.  The tool can be implemented on the Arc Hydro USA dataset (available for download at the top of this page) by following these nine steps.

      1.)  Set the flow direction for the HydroEdge feature class.  Under the Network Tools menu, select Set Flow Directions.  

      2.)  Populate the NextDownID attribute in the HydroJunction feature class.  Under the Attribute Tools menu, select Find Next Downstream Junction.

      3.)  Select the upstream and downstream Watershed features.  Press the Trace by NextDownID Attribute button .  You will see the following user interface.  

Under "Setup Data", Map is the name of the data frame being used and Layer is the feature class that will be selected and traced upstream/downstream (either HydroJunction or Watershed).  

        4.) Select the Watershed feature class as the layer to be traced

Under "Trace Type" there are three options for which features are selected by the tool.

        5.) Select  to find both the upstream and downstream path

Under Related Layer, the tool allows the option of selecting features for other feature classes which are related to the feature class being traced.  For example, if HydroJunction is the feature class whose flow path is being traced, the features in the MonitoringPoint, Waterbody, or Watershed feature class that are related to the selected features in the HydroJunction feature class will also be selected

        6.)  For our purposes, do not select any of the related layers 

The tool also allows the option of showing all of the selected features for both the layer being traced and the related layers, or displaying only the related layer(s).

        7.) Select All to show all selected features.

        8.) Press OK

        9.) Select a watershed by pressing the left mouse button on the watershed.

After a watershed has been selected, you should see the the flow path for water passing through the selected watershed.  A typical example is shown below.

 

The red point near the top of the selected watersheds is where the user clicked to initiate the upstream/downstream tracing.  From that starting watershed, the upstream and downstream watersheds were selected.  

 

    Extraction of Time Series Data from the Geodatabase into Microsoft Excel

Another useful feature of the geodatabase is that it offers easy extraction of data into Microsoft Excel.  Thus, if one would like to use Excel to analyze time series data for a certain gage over a specific period of time, the time series table can be queried and the results imported into Excel.  Following is a description of the steps necessary for data extraction from a Access geodatabase (.mdb) to an Excel Spreadsheet (.xls). 

1.)   Open Microsoft Excel

2.)   Under the menu Data, selected Get External Data and then New Database Query.

3.)  Select MS Access Database as the Data Source.  Press OK.

4.)  Browse to to directory where Arc Hydro USA was downloaded to and select ArcHydroUSA.mdb as the Database.  Press OK.

5.)   On the left side of the interface, scroll down and select the TimeSeries Table and click the plus sign to the left of the name.  This will display all of the columns within the TimeSeries table.  Add the OBJECTID, TSDATETIME, and TSVALUE columns by highlighting each column and clicking the arrow pointing to the right.  Press Next.

6.)  Filter the data by selecting only measurements where the TSDATETIME (time the measurement was taken) is greater than or equal to the year 2000.  You could apply more specification to the TSDATETIME query by providing an upper limit to the search, and it is possible to also query other columns in addition to TSDATETIME.  For this example, we'll keep it simple.  Press Next.  

7.)  Sort the data in an ascending order by the TSDATETIME and press Next.

8.)  Choose to Return Data to Microsoft Excel and press Finish.

9.)  After a few seconds, you are prompted to select where you would like to export the data.  Keep the default and press OK.  

10.)  It may take a few minutes to import the data based on your Query.  Once the process has finished, you should see something similar to the image below.  You have successfully imported data from the TimeSeries table in the Microsoft Access database into Microsoft Excel.

 

11.)   It is possible to edit the query by clicking the left most button on the External Data toolset shown above.

12.)  Suppose we would like to limit our search to one gage.  We can edit our original query by clicking on the left most button, pressing next, and then adding the query for FeatureID as shown below.  

13.)  This query will further define the data to be imported into Excel.  Thus, we will now see in Excel only time series data from 2000 on for the gage with FeatureID equal to 1000001.  The Excel worksheet is updated automatically according to the new query.

 

These materials may be used for study, research, and education, but please credit the authors and the Center for Research in Water Resources, The University of Texas at Austin. All commercial rights reserved. Copyright 2001 Center for Research in Water Resources.