Scientific Investigations Report 2009–5188
AbstractAFINCH (Analysis of Flows in Networks of CHannels) is a computer application that can be used to generate a time series of monthly flows at stream segments (flowlines) and water yields for catchments defined in the National Hydrography Dataset Plus (NHDPlus) valueadded attribute system. AFINCH provides a basis for integrating monthly flow data from streamgages, wateruse data, monthly climatic data, and landcover characteristics to estimate natural monthly water yields from catchments by userdefined regression equations. Images of monthly water yields for active streamgages are generated in AFINCH and provide a basis for detecting anomalies in water yields, which may be associated with undocumented flow diversions or augmentations. Water yields are multiplied by the drainage areas of the corresponding catchments to estimate monthly flows. Flows from catchments are accumulated downstream through the streamflow network described by the stream segments. For stream segments where streamgages are active, ratios of measured to accumulated flows are computed. These ratios are applied to upstream water yields to proportionally adjust estimated flows to match measured flows. Flow is conserved through the NHDPlus network. A time series of monthly flows can be generated for stream segments that average about 1mile long, or monthly water yields from catchments that average about 1 square mile. Estimated monthly flows can be displayed within AFINCH, examined for nonstationarity, and tested for monotonic trends. Monthly flows also can be used to estimate flowduration characteristics at stream segments. AFINCH generates output files of monthly flows and water yields that are compatible with ArcMap, a geographical information system analysis and display environment. Chloropleth maps of monthly water yield and flow can be generated and analyzed within ArcMap by joining NHDPlus data structures with AFINCH output. Matlab code for the AFINCH application is presented.

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Holtschlag, D.J., 2009, Application guide for AFINCH (analysis of flows in networks of channels) described by NHDPlus: U.S. Geological Survey Scientific Investigations Report 20095188, 106 p.
Preface
Abstract
Introduction
Methods and Data Used in AFINCH Modeling
AFINCH Code
Mapping Water Yields in Catchments and Streamflow at Flowlines
Limitations of AFINCH and Suggestions for Future Development
Summary
Acknowledgments
Literature Cited
Appendix 1. Starting AFINCH (AFinch)
Appendix 2. A Graphical User Interface for AFINCH (AFinchGUI)
Appendix 3. Initialize Common Variables in the Matlab Workspace (AFIniAFStruct)
Appendix 4. Setup Data for AFINCH (AFSetupData)
Appendix 5. Read in National Land Cover Data (AFReadNLCD)
Appendix 6. Read in PRISM Precipitation Data (AFReadPrismPrec)
Appendix 7. Associate NHDPlus Flowlines with Streamflow Gaging Stations (AFGenStrucData)
Appendix 8. Read in monthly Streamflow Data at Gaging Stations (AFReadInFlowWY)
Appendix 9. Develop and Display Annual Network Design Matrices (AFStaBasinGridComIDWY)
Appendix 10. Plot the Relation Between Drainage Areas and Flows at Streamgages (AFPlotAreasFlows)
Appendix 11. Plot Image of Monthly Water Yields by Streamgage (AFYieldImage)
Appendix 12. Read in PRISM Air Temperature Data (AFReadPrismTemp)
Appendix 13. Compute the Previous Month's Precipitation (AFGenLag1Precip)
Appendix 14. Create Boxplots Showing the Distribution of Explanatory Variables (AFBoxplotExplanVar)
Appendix 15. Calls Graphical User Interface for UserSpecified Water Yield Regression Equation (AFCallRegCheckBox)
Appendix 16. Graphical User Interface for UserSpecified Regression Equation (AFRegCheckBoxGUI)
Appendix 17. Estimate Parameters for UserSpecified Regression Equation with Data for the Entire Period of Analysis (AFRegressPOA)
Appendix 18. Estimate Parameters for Regression Equation by Water Year (AFRegressByWY)
Appendix 19. Plot Annual Estimates of Regression Equation Parameters (AFPlotRegressCoeff)
Appendix 20. Compute Estimates of Adjusted Incremental Water Yields and Flows (AFQEstAdjInc)
Appendix 21. Compute Constrained Estimates of Adjusted Incremental Water Yields and Flows (AFQConAdjInc)
Appendix 22. Plot monthly Estimates of Flows for the Period of Analysis (AFPlotQmMeaEst)
Appendix 23. Write Estimates of Water Yields and Flows to Files (AFWrtQYEstCon)
Appendix 24. Accumulate Flows Throughout the NHDPlus Network (AFConFlowAccum)
Appendix 25. Plot Time Series of Monthly Flows and Display Monthly Flow Duration Curves (AFTrendDurations)
Appendix 26. Compute Kendall's tau Correlation Coefficient and Sen's Monotonic Trend Slope Statistic (AFKenSen)
Appendix 27. Graphical User Interface for Plotting Images of Monthly Water Yields (AFYieldAtGagesGUI)
Appendix 28. Plot Image of Water Yields at Historically Gaged Streams (AFImagePOAYield)
Appendix 29. Identify Streamgages and Gaging Activity from Image Plot(AFid)