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The StreamStats Program

User Instructions

Please help us conserve our server system resources and close the Interactive Map window when you are finished using it. Doing so will help ensure system availability for all users. Thank you.

The new network navigation, and estimating flows based on similar gages have not yet been implemented for all states. These processes will be added in the near future.

Also, we recommed not to bookmark the actual interactive map because the URL can change. If you do bookmark, please use the state intro page instead - this URL will not change. For example, Massachusetts state intro page is

The Help button to the far right of the toolbar above the map frame launches a new window that contains a help facility that provides detailed instructions on general use of the interface, such as using the toolbar, identifying features, using the magnifier, displaying map layers, etc. Users should review this information before attempting to use StreamStats. The information provided through the Getting Started and Quick Tour links in the help facility are particularly helpful. This help facility is somewhat generic, and does not provide instructions for use of the custom tools built into StreamStats. Instructions for those tools are provided below. NOTE: Users should always wait until processing is completed and the map is re-drawn before attempting to do additional work with StreamStats.

Sites of interest may be located by use of the Zoom In button to the top left of the toolbar above the map frame or by use of the Zoom To pull-down menu toward the right end of the toolbar.

Use of the Zoom In button:

Use of the Zoom To tools:

The Zoom To pull-down list near the center of the toolbar provides access to three separate tools for zooming in to specified locations. These tools allow users to zoom into a provided latitude and longitude, a place name, or a National Hydrography Dataset (NHD) reach code. To use one of these tools:

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Zooming to a specified scale:

To the right of the Zoom To pull-down list is another pull-down list in which the current scale is shown. To change scales with the map centered on the present location, click on the down arrow to the right side of the pull-down list and select the desired scale. Note that to delineate a drainage-basin boundary for an ungaged site, the map must be zoomed into a scale of at least 1:24,000.

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Selecting a site and delineating a watershed:

When an appropriate scale is reached, 1:24000 or greater, the map frame displays either a dark blue grid or a dark blue line to represent the stream network, depending on which state application is used and the spatial data on which it is based. The stream network was derived entirely or in part from digital elevation data, and does not always agree exactly with the streams shown on the topographic base map.

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Editing Basin Boundaries:

Basin boundaries determined by StreamStats can be edited to add or remove parts of the delineated drainage basin. Users may want to modify the boundaries to correct errors in the delineations resulting from inaccuracies in the spatial data used to determine them, or they may want to determine the effects of proposed land-use changes or changes that were already made but are not reflected in the topographic map and spatial data.

Editing of basin boundaries is done by use of a combination of the Edit a delineated basin tool button and the adjacent shape selection menu.

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Getting Streamflow Statistics for the Ungaged Site:

Estimates of streamflow statistics for user-selected ungaged sites can be obtained by two methods in StreamStats. The Watershed Delineation from a Point tool must be used first to obtain the drainage-basin boundary for the point of interest before either of the flow-estimation tools may be used. The Estimate Flows Using Regression Equations tool provides estimates by measuring needed basin characteristics and solving USGS-developed regression equations. The Estimate Flows Based on Similar Streamgaging Stations tool estimates streamflow statistics by applying the flows per unit area for streamflow statistics at a nearby gaging station to the drainage area for the ungaged site. The theoretical basis for these methods and the outputs provided by StreamStats are explained in more detail on the Ungaged Sites page.

To obtain estimates based on USGS regression equations:

To obtain estimates based on flows at nearby similar gages:

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Editing Parameters and Recomputing Flows:

The Edit Parameters and Recompute Flows button allows users to modify the basin characteristics that were measured by StreamStats in the Estimate Flows Using Regression Equations, which must be completed before the Edit Parameters and Recompute Flows tool can be used. Upon selecting this tool, a pop-up window will appear that lists all of the basin characteristics that were used to solve the regression equations for the selected location. Users can type in new values for any of the basin characteristics. Click on the Recompute Flows button and a new ungaged site report will appear that looks the same as the report from the Estimate Flows Using Regression Equations process except that the title indicates that edited parameters were used to obtain the flow estimates.

The Edit Parameters and Recompute Flows process is useful for testing the sensitivity of the regression equations to changes in the basin characteristics used as parameters in the equations. Multiple scenarios can be tested in succession by (1) clicking with the right mouse button on the output window to cause a menu to appear, (2) selecting Back from the menu to cause the parameter editing window to reappear, (3) modifying the characteristics again, and (4) clicking on the Recompute Flows button to obtain new estimates. The Edit Parameters and Recompute Flows process also can be used to determine changes in flow that can be expected due to a planned or natural change in a parameter. For example, the drainage area could change as a result of mining operations, or a change in mean annual precipitation could be expected as a result of anticipated climate change.

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Getting Additional Basin Characteristics for an Ungaged Site:

The basin characteristics provided in the output from the Get Statistics tool are limited to those needed to solve the regression equations that are available at the user-selected point. Often, additional basin characteristics can be obtained by use of the Basin Characteristics tool button .

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Getting Statistics for a USGS Data-Collection Station:

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Stream Network Navigation (Network Tracing):

The theory of network navigation is explained on the Network Navigation page. StreamStats contains three tools for network navigation, Configure NHD, Trace From Outlet, and Ad Hoc Trace. The stream network on which the trace is to be performed should be displayed in the user interface before attempting a trace. If a site already has been selected and a drainage-basin boundary has been obtained:

If a watershed basin has not already been delineated:

In either case, after the network trace has been completed a pop-up Web-browser window will appear with the results from the trace, and the map frame will redraw, with the stream reaches identified in the trace highlighted. Click on the fields with hyperlinks in the output tables to obtain additional information.

To clear all network trace results, click on the 'Clear Selected Features from NHD Trace' button .

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Raindrop Trace to Network:

This tool traces from the point chosen by the user using the underlying flow direction grid associated to that HUC until intersecting the current active network layer, the trace then follows the network downstream to the outlet.

How to use the function:

The tool traces from the user specified point using the underlying flow direction grid until intersecting with the active network. It then traces downstream along the network. The blue point represents the point clicked by the user. The green point is the location where the trace first intersects the network.

The function also displays the reachcode code and measure of the location where the trace first intersect the network layer.

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Trace Network Path within Watershed and Show Profile:

This tool traces the network path and generates the profile along the main flow path from the user specified trace point to the watershed outlet. The watershed must be entirely located within one HUC.

How to use the function:

The tool displays the path in red between the user specified (blue point) and the watershed outlet (yellow star).

Also, a graph is generated that shows the profile corresponding to the flow path.

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Terrain Profile:

This tool generates the terrain profile of the user specified points using the underlying Digital Elevation Model (DEM) grid.

How to use the function:

This tool displays the profile path in red, user specified points as green points.

Also, a graph is generated that shows the profile corresponding to the user specified points.

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Downloading Shapefiles:

The StreamStats application allows the user to download shapefiles of the delineated watershed and point. The shapefiles can be displayed and used for further analysis in other GIS applications. Shapefiles should be retained to serve as documentation of the exact point that was used in the delineation and the resulting watershed polygon. These shapefiles will be needed to verify what was done if there is any reason to question the results from StreamStats.

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Print the view in the Map Frame:

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Brief descriptions of other buttons on the Toolbar are on the Help Button.

Reporting Problems:

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