Calculator for Low Flows (CaLF)
As part of the Environmental Flows Information System for Texas (EFIS) project, a Microsoft Excel-based application called the Calculator for Low Flows was developed. CaLF is a tool for: (1) downloading USGS daily streamflow data; (2) calculating the seven-day two-year low flow (7Q2); (3) calculating and plotting the flow duration curve; (4) calculating the harmonic mean; (5) calculating the Lyons' method monthly minimum streamflow and the modified Lyons' method streamflow and adjusting them via a Drainage Area Ratio (DAR) if desired; and (6) graphing these two minimum flows. The tool uses web services to download U.S. Geological Survey (USGS) mean daily streamflow data via the internet. More information on the 7Q2 can be found here and more on the Lyons' method here.
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