Flood Frequency – Multi-Distribution Tool

Paste annual maximum flows and compare design floods from three distributions: Gumbel (EV-1), Log-Pearson III and Log-Normal. Includes a comparison table, plotting positions, and charts with trendline + R².

1. Data & Options Sample & Return Periods

Enter annual peak flows (one value per year). Values can be separated by commas, spaces or new lines. For log-based distributions all flows must be > 0.
Only used for labels; no unit conversions are performed.
Comparison always shows all 3 distributions.
Comma / space separated. Uses p = 1 − 1/T.
Paste one value per line, or comma-separated. The tool ignores blank entries. At least 5 values recommended.
HEC-SSP-like LP-III (Gamma inversion) Charts + trendline + R² Plotting positions