Ampurire Ignatius

These four methods are crucial in hydrological analyses, particularly for assessing streamflow, precipitation, and other hydrological parameters used in the design of water management structures and water resource management.

1. Pearson Type III Distribution

• Describes asymmetric distributions that frequently occur in hydrology (e.g., annual maximum flow distribution).
• Takes into account the shape of the distribution through the skewness coefficient.
• Widely used in the analysis of extreme hydrological events, such as floods.

2. Normal (Gaussian) Distribution

• A symmetric distribution used when data are centered around the mean value.
• Often applied in hydrology for analyzing parameters such as precipitation or groundwater levels, where extreme values are not critical.
• Less suitable for flood estimation as it disregards data asymmetry.

3. Log-Pearson Type III Distribution

• One of the most commonly used distributions in the analysis of annual maximum flows.
• Applied when data follow a log-normal distribution, which is often the case in hydrological time series.
• Used for estimating flood recurrence intervals and calculating the probability of extreme hydrological events.

4. Extreme Value Distribution (EV)

• Specifically developed for analyzing extreme events, such as maximum precipitation and flood peaks.
• The Generalized Extreme Value (GEV) distribution includes Gumbel, Fréchet, and Weibull distributions.
• Essential for risk analysis and water resource management under climate change conditions.

Application in Solving Hydrological Problems

• Design of dams and flood protection structures.
• Risk analysis of extreme precipitation and flash floods.
• Sizing of hydraulic systems.
• Assessment of hydrological extremes in the context of climate change.