Puerto Rico N-day Low-Flow Regression Files

Dates

Publication Date: 2021-06-24
Start Date: 1945-07-01
End Date: 2018-09-30

Citation

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, https://doi.org/10.5066/P9Y2QVJ6.

Summary

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 [...]

Summary

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 (ie. record length and variance) and accounts for correlated streamflows and time-sampling errors (Eng and others, 2009). Performance metrics from the Weighted-multiple-linear REGression Program (WREG) were analyzed to determine drainage area, mean total annual reference evapotranspiration, and minimum basin elevation as the explanatory variables that provided the best results. Values for the correlation smoothing function in were alpha equal to 0.003 and theta equal to 0.96. This data release includes a SWToolbox_output_files folder that contains supporting data used to format the WREG input files, xday_lowflow folders (where x refers to 1, 7, 14, or 30) that contain (1) the WREG input files FlowChar, LP3G, LP3K, LP3s, SiteInfo, and the 28 station nday timeseries files (USGSxxxxxxxx); and (2) a WREG_gls_results folder that contains output for the 2yr, 5yr, and 10yr nonexceedance probability flows.

References Cited:

Eng, K., Chen, Y., and Kiang, J.E., 2009, User’s guide to the weighted-multiple-linear-regression program (WREG version 1.0): U.S. Geological Survey Techniques and Methods, book 4, chap. A8, 21 p., https://pubs.usgs.gov/tm/tm4a8.

Kiang, J.E., Flynn, K.M., Zhai, T., Hummel, P., and Granato, G., 2018, SWToolbox—A surface-water tool-box for statistical analysis of streamflow time series: U.S. Geological Survey Techniques and Methods, book 4, chap. A–11, 33 p., https://doi.org/10.3133/tm4A11.

Contacts

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

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PR_nday_lowflow_regression_files.xml Original FGDC Metadata	View	36.35 KB	application/fgdc+xml
1day_lowflow.zip		95.79 KB	application/zip
7day_lowflow.zip		96.45 KB	application/zip
14day_lowlfow.zip		97.02 KB	application/zip
30day_lowlfow.zip		96.9 KB	application/zip
PR_nday_lowflow_SWToolbox_output_files.zip		62.73 KB	application/zip

Related External Resources

Type: Related Primary Publication

Williams-Sether, T., 2021, Estimating flow-duration statistics and low-flow frequencies for selected streams and the implementation of a StreamStats web-based tool in Puerto Rico: Scientific Investigations Report, https://doi.org/10.3133/sir20215054.	https://doi.org/10.3133/sir20215054

Purpose

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.

Puerto Rico N-day Low-Flow Regression Files

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