Frequency Analysis and Draw IDF Charts


Below, we provide a detailed description of the contents of the folders included in the zip file project. This project contains various files and charts that are essential for understanding the Specifications of Distribution and IDF (Intensity-Duration-Frequency) charts.

The primary focus of these folders is to offer comprehensive visual and statistical analyses using different probability distributions. The distributions covered include Gamma, Gumbel, Lognormal, Weibull, and Exponential distributions. These distributions are commonly used in hydrological and meteorological studies to model and analyze extreme events, such as heavy rainfall or flood occurrences.

  • 1- In the "IDFs" folder, you'll find six files named after their respective distributions. Each file contains a table displaying return periods and corresponding datetime values, spanning from one day up to six days.
  • 2- In the "PDF_CDF" folder, you'll find four files named after the distributions they represent. It's important to note that these files contain fittable distributions, excluding EV1 and Empirical. For the other four methods, we fit the distribution first, and then calculate the cumulative distribution function (CDF) and probability density function (PDF) based on a specific formula. Each file in this folder consists of two separate sheets—one for CDF data and another for PDF data.
  • 3- The QQPlot folder contains four files corresponding to four distributions, each containing QQ-Plot data. QQ-Plot compares the quartiles of the empirical method with those of the theoretical distributions (such as Gamma, Gumbel, etc.).
  • 4- The folder named 'Specifications of Distribution' houses four files, each detailing the specifications of distribution for various time scales ranging from 1-day to 6-day intervals. These files provide comprehensive information about the characteristics and parameters of the distributions employed across different time frames.
  • 5- The file named 'Maximum Intensity Table.xlsx' compiles the maximum rainfall recorded annually across all time scales, encompassing 1-day rainfall, 2-day rainfall, and so forth up to 6-day rainfall intervals.
  • 6- The file titled 'Check_Dist.xlsx' serves as a repository for the outcomes of two pivotal tests: the Kolmogorov-Smirnov test and the Chi-Square test. These tests are instrumental in gauging the disparity between empirical and theoretical distributions. By examining the results of these tests, users can make informed decisions regarding the selection of an appropriate distribution for their data analysis needs.