 |
| Titel |
Flood frequency analysis supported by the largest historical flood |
| VerfasserIn |
W. G. Strupczewski, K. Kochanek, E. Bogdanowicz |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1561-8633
|
| Digitales Dokument |
URL |
| Erschienen |
In: Natural Hazards and Earth System Sciences ; 14, no. 6 ; Nr. 14, no. 6 (2014-06-20), S.1543-1551 |
| Datensatznummer |
250118502
|
| Publikation (Nr.) |
 copernicus.org/nhess-14-1543-2014.pdf |
|
|
|
|
|
| Zusammenfassung |
The use of non-systematic flood data for statistical purposes depends
on the reliability of the assessment of both flood magnitudes and their return period.
The earliest known extreme flood year is usually the beginning of the
historical record. Even if one properly assesses the magnitudes of historic
floods, the problem of their return periods remains unsolved. The matter at
hand is that only the largest flood (XM) is known during whole historical
period and its occurrence marks the beginning of the historical period and
defines its length (L). It is common practice to use the earliest known flood
year as the beginning of the record. It means that the L value selected is an
empirical estimate of the lower bound on the effective historical
length M. The estimation of the return period of XM based on its occurrence
(L), i.e. ^M = L, gives a severe upward bias. The problem
arises that to estimate the time period (M) representative of the largest
observed flood XM.
From the discrete uniform distribution with support 1, 2, ... , M of the
probability of the L position of XM, one gets ^L = M/2. Therefore
^M = 2L has been taken as the return period of XM and as the
effective historical record length as well this time. As in the systematic
period (N) all its elements are smaller than XM, one can get
^M = 2t( L+N).
The efficiency of using the largest historical flood (XM) for large
quantile estimation (i.e. one with return period T = 100 years)
has been assessed using the maximum likelihood (ML) method with various length of systematic
record (N) and various estimates of the historical period length
^M comparing accuracy with the case when systematic records
alone (N) are used only. The simulation procedure used for the purpose
incorporates N systematic record and the largest historic flood
(XMi) in the period M, which appeared in the Li year of the historical period. The simulation results for
selected two-parameter distributions, values of their parameters, different
N
and M values are presented in terms of bias and root mean square error RMSEs of the quantile of
interest are more widely discussed. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|