Stream flow data is necessary to auto-calibrate a project in i-Tree Hydro. This is only possible in watershed-area projects; stream gauge data used in i-Tree Hydro represents discharge from a given watershed a/k/a drainage basin.
Auto-calibration is optional: i-Tree Hydro can run using Suggested Default Parameters which are based on national averages for the United States, and that parameter set can be manually adjusted based on local knowledge of the project area (for example, changing the soil type based on the average soil in the project area).
Picking a stream gauge from a map:
Stream flow data for many locations around the United States is pre-loaded into i-Tree Hydro for the convenience of users, after having been screened for quality and pre-processed. Such stations are available through the map selection option, limited to time frames between 2005 and 2012.
Using your own stream flow file:
Standard stream flow data in the raw format (including gauges pre-loaded into i-Tree Hydro) come from the United States Geological Survey (USGS) Water Watch service. To manually obtain raw stream flow data in standard format, navigate to http://waterwatch.usgs.gov/index.php?id=ww_current and select the state which contains the stream gauge you'd like to calibrate to. Hover your mouse over stream gauges of interest and click on them to view details. When you've found one that suits your project, navigate to that stream gauge's USGS page by clicking its ID#. (In terms of what to look for, we recommend selecting a stream gauge based on relevance of location, drainage area size, and available period of discharge measurements for your project.) On the stream gauge's USGS page, from the Available Data drop-down menu, select "Time-Series: Current/Historical Observations".
To check the quality of the data you're going to use, input the time frame for your project and view the graph of the Discharge parameter to confirm data completeness and normality. It is important to use complete and normal stream gauge data. Data with gaps (missing measurements) larger than a day, or abnormal hydrographs, can create erroneous calibration results.
If the data you've checked looks good and you're ready to download it for use in i-Tree Hydro, switch the Output Format to Tab-separated and press Go. The txt file output can be saved as is and input into i-Tree Hydro as a raw stream flow file. Here is an example raw stream flow file (headers may differ slightly and that's usually not a problem): http://www.itreetools.org/hydro/resourc ... xample.txt
Processed stream flow files
Alternatively for advanced users, you may format your own observed discharge data as a processed stream flow file. Example: http://www.itreetools.org/hydro/resources/qobs.txt
Note that the units for processed observed discharge are meters per hour. This is also known as specific discharge and can be calculated as follows: Observed discharge (cubic meters per hour) divided by drainage basin area (square meters) equals specific discharge (meters per hour).
The above method of downloading raw stream flow data only works in the United States. We are currently working to make user-provided stream flow data from alternative sources more accessible for use with i-Tree Hydro by streamlining the formatting process.
International users may be able to format their own observed discharge data as a processed streamflow file for use in calibrating i-Tree Hydro. The processed streamflow can be prepared in a spreadsheet and exported for Hydro v5 as a space-delimited text file or for Hydro v6 as a comma-separated values file (we do not yet have a support system in place to help international users do this formatting). Please note that the processed streamflow file is listing hourly specific discharge. You can calculate specific discharge of the gauge (meters per hour) by dividing the volumetric discharge observations (cubic meters per hour) by the gauge's contributing area (square meters).
Section for FAQs regarding i-Tree Hydro
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