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Puerto Rico N-day Low-Flow Regression Files


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Williams-Sether, T., 2021, Data Files for the Development of Regional Regression Equations for Flow-Duration Statistics and N-day Low-Flow Frequencies for Ungaged Stream Locations in Puerto Rico Using Data Through Water Year 2018: U.S. Geological Survey,


A generalized least squares (GLS) technique was used with at-site n-day low-flow time series and frequencies, from SWToolbox (Kiang and others, 2018), and 14 basin characteristics (basin perimeter, drainage area, maximum basin elevation, mean total annual reference evapotranspiration, groundwater head, length of longest flow path, minimum basin elevation, runoff-curve number, relief, ruggedness, slope ratio, percentage of hydrologic soil type B, available water capacity, and total length of streams in a basin) for 28 selected streamflow gaging stations in Puerto Rico to calculate regional n-day low-flow frequency regression equations for ungaged stream locations. The GLS approach assigns weights based on uncertainty of the observations [...]


Point of Contact :
Tara J Williams-Sether
Process Contact :
Tara J Williams-Sether
Originator :
Tara J Williams-Sether
Metadata Contact :
Tara J Williams-Sether
Publisher :
U.S. Geological Survey
Distributor :
U.S. Geological Survey - ScienceBase
SDC Data Owner :
Dakota Water Science Center
USGS Mission Area :
Water Resources

Attached Files

Click on title to download individual files attached to this item. 95.79 KB application/zip 96.45 KB application/zip 97.02 KB application/zip 96.9 KB application/zip 62.73 KB application/zip


To provide updated flow-duration exceedance probabilities, n-day low-flow frequencies, and selected basin characteristics used to develop regional regression equations to estimate flow-duration statistics and n-day low-flow statistics at ungaged locations in Puerto Rico. These regression equations will be implemented in the Puerto Rico StreamStats application.



  • USGS Dakota Water Science Center



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