Flood Frequency Analysis Tool

Gumbel, Log‑Normal, and Log‑Pearson III. Simple inputs, compact tables, and charts.

Inputs

Advanced (optional)
HEC-style labeling: the 0.05 column is commonly the upper bound and 0.95 is the lower bound (exceedance probability labels).
Ready.
Notes:
• Return period T is converted to percent chance exceedance = 100/T.
• Best fit is based on Weibull plotting positions comparing observed vs fitted quantiles.
• No bold text is used except the page title.

Results

Distribution parameters and goodness‑of‑fit

Distribution Parameter 1 Value Parameter 2 Value Parameter 3 Value Fit metric

Quantiles table

Charts

Black line: power trendline through the computed points (y = a·x^b). Blue diamonds: computed quantiles at your return periods.

Diagnostics