Introduction to Hydro-FIT

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Hydro-FIT is a statistical tool developed by HydroMetriks, LLC, that facilitates the frequency analysis of various types of hydrological and meteorological data.  Hydro-FIT uses the method of L-moments to calculate descriptive statistics (L-moments) for a dataset. These L-moments are used to fit any of 13 different standard distributions, which are used to estimate the growth curve of the data.  Hydro-FIT also has the ability to estimate the impacts of climate variability on event frequency and intensity.  The objective has been to … Read More

“Regional Frequency Analysis” by Hosking & Wallis

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The book titled “Regional Frequency Analysis: An Approach Based on L-Moments” is the current authority on using L-Moments in any type of frequency analysis.  Every step of the process is described in detail and examples are given along the way to make the method clear.  The code that was developed into the current version of Hydro-FIT was inspired by and mimics the steps described in this book.  Obtaining and reading a copy of “Regional Frequency Analysis” is highly recommended.  This … Read More

“Data Screening” Window

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The “Data Screening” window is the initial window following the “Title Screen” from which you may load and screen the data that you would like to analyze.  This window is divided into three panels titled ‘Load Data’, ‘Data Screening’, and ‘Index Analysis’.  After the data input file is selected, you can choose the resolution of the data, the analysis and data types, the beginning year (in the case of extreme value analysis or beginning month (if a specific period of the year is … Read More

Index Analysis Plot

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Hydro-FIT has the ability to calculate the correlation between 39 different global climate indices and the input data using a lag time that is supplied by the user.  By clicking the ‘Graph’ button on the “Data Screening” window and using the specified lag time, Hydro-FIT will display plots of the global climate indices vs. the input data for the five climate indices with the highest correlations along with their respective values of R2.  The relationship between any of these indices and … Read More

“Site Analysis” Window

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The screen that appears after clicking the ‘Site Analysis’ button within the ‘Data Screening’ window is called the ‘Site Analysis’ window.  The ‘Site Analysis’ window is organized into four parts that allow the user to select a valid site (determined during data screening) and view pertinent statistics associated with that site, to display any of a variety of plots pertaining to the selected site or to all sites as a whole, to select one or more standard distributions to display … Read More

Time Series Plot

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Hydro-FIT initially allows the user to view a time series of the data for any of the data site locations when the “Site Analysis” opens. If there is no index analysis component to the current analysis, then the plot will appear as a typical time series graph (not shown), where the sites that meet the initial data screening criteria are plotted as blue circles and connected by a line graph. Otherwise, the plot will look similar to the graph shown here, … Read More

“t3 vs. t4” Plot

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This “t3 vs. t4” plot illustrates values of t3 plotted against t4 for each site as light gray dots. The black dot represents the site that has been selected in the site drop-box. In addition, the t3/t4 relationships for all 2- and 3-parameter distributions are graphed. The 2-parameter distributions are plotted as points, while 3-parameter distributions are plotted as curves; distributions containing greater than 3 parameters (e.g. Kappa and Wakeby) are not defined on this plot. The closeness of a data point … Read More

PDF Plot

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A plot similar to the one shown here will appear when the user selects the ‘PDF’ radio button.  The data for the site selected in the site drop-box are plotted as a histogram.  In addition, the PDF’s of all selected distributions are plotted as curves of various colors. There are 13 standard distributions included within the current version of Hydro-FIT. The user can plot or remove any of the distributions on the PDF graph by clicking the checkbox(es) adjacent to the … Read More

Growth Curves

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Exceedance (shown) and non-exceedance (not shown) growth curves can be plotted when their respective radio buttons are selected.  The recurrence interval is plotted on the x-axis on a log scale while the variable of interest is plotted on the y-axis; the data for the selected site are plotted as a gray growth curve.  In addition, growth curves for all selected distributions are plotted using various colors. There are 13 standard distributions included within the current version of Hydro-FIT. The user can plot or remove any of … Read More

Contour Plot

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A contour plot of a rectangular region that contains all of the sites included in the current analysis will be displayed when the user clicks the ‘Contour Map’ radio button. The contour plot will initially display filled contours of the data calculated for an exceedance frequency of 0.95 (or a 20-year event) using the Gumbel distribution. The plot shown illustrates the 20-year contour plot for a dataset containing 50 years of rainfall projection data over the United States using the … Read More