THESIS
2012
xv, 319 pages : illustrations (some color), color maps ; 30 cm
Abstract
In this study, regional frequency analysis of extreme rainfall were conducted using
two different methods based on the most updated rainfall records in Hong Kong. The
results of the analysis were also compared. The two methods are index-event
L-moment based method of Hosking and Wallis (HW) and hierarchical region (HR)
method. This study analyzed the annual maximum rainfall series of duration 5-, 30-,
60-, 120-, 240-, 360-, 480-, 1080-, and 1440-min from a total of 122 automatic
raingauges with record lengths varying from 10 to 26 years. HW method divided the
entire territory of Hong Kong into 3 to 5 hydrologically homogeneous sub-regions
according to geographical attributes (latitude, longitude and elevation) and mean
annual rainfall (MAR). HR method classified Hong Kong into...[
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In this study, regional frequency analysis of extreme rainfall were conducted using
two different methods based on the most updated rainfall records in Hong Kong. The
results of the analysis were also compared. The two methods are index-event
L-moment based method of Hosking and Wallis (HW) and hierarchical region (HR)
method. This study analyzed the annual maximum rainfall series of duration 5-, 30-,
60-, 120-, 240-, 360-, 480-, 1080-, and 1440-min from a total of 122 automatic
raingauges with record lengths varying from 10 to 26 years. HW method divided the
entire territory of Hong Kong into 3 to 5 hydrologically homogeneous sub-regions
according to geographical attributes (latitude, longitude and elevation) and mean
annual rainfall (MAR). HR method classified Hong Kong into 5 MAR-based
sub-regions and established regional functional relationships between extreme rainfall
statistics and MAR. Goodness-of-fit Z-test and LMR diagram were used to select the
best-fit regional distributions from five three-parameter probability distributions (GEV,
GLO, GPA, LN3 and PE3) and the five-parameter Wakeby distribution. Relative
difference and root-mean square difference of the analysis results by the two
regionalization methods were assessed with reference to the at-site rainfall
depth-duration-frequency. Hosking-Wallis method was recommended here due to its
better performance in the empirical assessment and more rigorous theoretical basis,
development and adoption in worldwide. Several factors associated to the sample data
and procedures of Hosking-Wallis method (varying site record lengths, number of
clusters, and distance measure for discordant site detection) were also studied.
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