Performance of flood frequency pooling analysis in a low CV context = Performances de l'analyse de fréquence de crues regroupées dans un contexte de coefficient de variation faible

Das, S. and Cunnane, C. (2012) Performance of flood frequency pooling analysis in a low CV context = Performances de l'analyse de fréquence de crues regroupées dans un contexte de coefficient de variation faible. Hydrological Sciences Journal, 57(3), pp. 433-444. (doi: 10.1080/02626667.2012.666635)

Abstract

Pooling of flood data is widely used to provide a framework to estimate design floods by the Index Flood method. Design flood estimation with this approach involves derivation of a growth curve which shows the relationship between XT and the return period T, where XT  = QT /QI and QI is the index flood at the site of interest. An implicit assumption with the Index Flood procedure of pooling analysis is that the XT –T relationship is the same at all sites in a homogeneous pooling group, although this assumption would generally be violated to some extent in practical cases, i.e. some degree of heterogeneity exists. In fact, in only some cases is the homogeneity criterion effectively satisfied for Irish conditions. In this paper, the performance of the index-flood pooling analysis is assessed in the Irish low CV (coefficient of variation) hydrology context considering that heterogeneity is taken into account. It is found that the performance of the pooling method is satisfactory provided there are at least 350 station years of data included. Also it is found that, in a highly heterogeneous group, it is more desirable to have many sites with short record lengths than a smaller number of sites with long record lengths. Increased heterogeneity decreases the advantage of pooling group-based estimation over at-site estimation. Only a heterogeneity measure (H1) less than 4.0 can render the pooled estimation preferable to that obtained for at-site estimation for the estimation of 100-year flood. In moderately to highly heterogeneous regions it is preferable to conduct at-site analysis for the estimation of 100-year flood if the record length at the site concerned exceeds 50.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Das, Dr Samiran
• Authors: Das, S., and Cunnane, C.
• College/School: College of Science and Engineering > School of Engineering
• Journal Name: Hydrological Sciences Journal
• Publisher: Taylor and Francis
• ISSN: 0262-6667
• ISSN (Online): 2150-3435