Statistical Hydrology and Flood Frequency

Continuous and Discrete Data

Siletz River, Oregon

Linear Trend Periodic Trend Change in Variance Change in Average

Relative Frequency Histogram - Skew

Cumulative Frequency Histogram

Mean Variance Skewness

Continuous Probability Density Function

Mixed Freq Dist’n Model

Effect of skewness on a distribution

Generalized skew coefficients

Relationship return period and return period

Flow Duration Curves Percent time flow value equaled or exceeded

Binomial Probability Mass Function

Exponential Distribution

Log Normal Dist Normal Dist Four PDFs matched to Siletz River data

Normal Probability Paper

Lognormal Probability Paper

Plotting position = m/(n+1) Lognormal Plot of Data - confidence intervals

Various Methods for plotting Probability of exceedance

Comparison of four fitted CDFs

Normal probability plot of river data -S S X Normal probability plot of river data