| Title: | Assessment of the combined effects of threshold selection and parameter estimation of Generalized Pareto Distribution with applications to flood frequency analysis |
| Authors: | Gharib, A., E.G.R. Davies, G.G. Goss and M. Faramarzi |
| Year: | 2017 |
| Journal: | Water |
| Volume (Issue): | 9(9) |
| Pages: | |
| Article ID: | 692 |
| DOI: | 10.3390/w9090692 |
| URL (non-DOI journals): | |
| Model: | SWAT |
| Broad Application Category: | hydrologic only |
| Primary Application Category: | flood impacts and/or processes |
| Secondary Application Category: | hydrologic assessment |
| Watershed Description: | 47 drainage areas within the 661,000 km^2 Province of Alberta, Canada. |
| Calibration Summary: | |
| Validation Summary: | |
| General Comments: | |
| Abstract: | Floods are costly natural disasters that are projected to increase in severity and frequency
into the future. Exceedances over a high threshold and analysis of their distributions, as determined
through the Peak Over Threshold (POT) method and approximated by a Generalized Pareto
Distribution (GPD), respectively, are widely used for flood frequency analysis. This study investigates
the combined effects of threshold selection and GPD parameter estimation on the accuracy of flood
quantile estimates, and develops a new, widely-applicable framework that significantly improves
the accuracy of flood quantile estimations. First, the performance of several parameter estimators
(i.e., Maximum Likelihood; Probability Weighted Moments; Maximum Goodness of Fit; Likelihood
Moment; Modified Likelihood Moment; and Nonlinear Weighted Least Square Error) for the GPD
was compared through Monte Carlo simulation. Then, a calibrated Soil and Water Assessment Tool
(SWAT) model for the province of Alberta, Canada, was used to reproduce daily streamflow series
for 47 watersheds distributed across the province, and the POT was applied to each. The Goodness
of Fit for the resulting flood frequency models was measured by the upper tail Anderson-Darling
(AD) test and the root-mean-square error (RMSE) and demonstrated improvements for more than
one-third of stations by averages of 65% (AD) and 47% (RMSE), respectively. |
| Language: | English |
| Keywords: | peak over threshold (POT); extreme value analysis; flood; extreme hydrological events;
flood quantiles |