Flood Flow Frequency Analysis 1-6-2009 1.0

It uses a Log Pearson Type-3 distribution for estimating quantiles.NaN need to be removed in the dataset. If any years have missing data, it will still assume to include that year as part of the sample size-- as stipulated in 17B guidelines. An exmaple MAT file is provided for the user to test. A nice enhancement to this function is a plot of the analyses. It is plotted in probability space-- SKEWED probability space! Because data may not be normally distributed, plotting in skewed space maintains a straight line for the final frequency curve.UsageSyntax:  [dataout skews pp XS SS hp] = b17(datain, gg, imgfile)   Input:datain = Nx2 double  datain(:,1) = year or datenum  datain(:,2) = peak annual flow rate  gg = a generalized weighted skew  imgfile = full path and file name to export the figure  Output:(is in the form of a N x 6 double, and all flows are in Log10)dataout(:,1) = Return Period (in years)  dataout(:,2) = Probability  dataout(:,3) = Final Frequency curve  dataout(:,4) = upper CI frequency curve  dataout(:,5) = lower CI frequency curve  dataout(:,6) = Expected Probability (N-1)  skews(1) = Station Skew  skews(2) = Station Skew outliers, zero removed  skews(3) = Synthetic Skew  skews(4) = Weight adjusted skew  pp(:,1) = gringorten plotting position  pp(:,2) = weibull plotting position  pp(:,3) = observations  XS = mean of Log10(Flow rates)  SS = standard deviation Log10(flow rates)  hp = historically adjusted weibull plotting position where historical peaks our high outliers are ranked in integer values (e.g. 1,2,3,etc.) and systematic observations are adjusted. Key features "Flood Flow Frequency Analysis": - estimates of a final frequency (based on a weighted skew) - confidence intervals (95%) for the final frequency - expected frequency curve based on an adjusted conditional probability - observed data with computed plotting positions using Gringorten and Weibull techniques - various Skews - mean of log10(Q) - standard deviation of log10(Q) - a probability plot that does not require a toolbox to create, but also plots the probability space using the computed weighted skew and not just the normal probability Requirements: - MATLAB 7.7 (R2008b)

Requirements:	No special requirements
Platforms:	Windows, Mac, *nix, Mac OSX, Linux, Matlab , Solaris
Keyword:	Annual,  Annual Extremes,  Extreme,  Flood,  Flood Frequency,  Flow Estimation
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