| Summary: | Thesis (M.Eng.)--Memorial University of Newfoundland, 1993. Engineering and Applied Science Bibliography: leaves 96-98. This thesis discusses the development and application of two principal methods of regional flood frequency estimation for the rivers in Aceh Province, Indonesia. -- The first method is based on index-flood approaches and the second method is the regression of flood quantiles on basin characteristics approach. -- For the index-flood approaches, the annual maximum floods at each site were standardized by the mean annual flood of the site. Five different index-flood methods were used to derive the regional frequency curve. These are Dalrymple's method, NERC method, the probability weighted moments method, the station year method and the L-moment method. -- For the multiple regression approach, the logarithm of each selected quantile of the annual maximum floods at each site of the nine river basins was regressed on its corresponding catchment variables. The least squares method was used lo develop the multiple regression equations. The derived regression equations were corrected for bias caused by the logarithmic transformation. -- The flood estimates obtained using the two regional methods were compared to at-site estimates and to those obtained from a previous study by the Institute of Hydrology (IOH), Wallingford (1983) for basins in Jawa and Sumatra. The estimates obtained by the various methods were also compared to each other for basins that were not used in the study to show the variability of the results. -- From a comparison of the two regional methods, the findings showed that all index flood approaches provided greater consistency and similarity in the estimation of flood quantile magnitudes. The L-moment method seemed to give the best compromise estimates, while the regression approach gave lower estimates for most stations and estimates were sometimes inconsistent. The estimates based on the IOH study gave estimates well above these obtained in this study especially for higher return period floods.
|
|---|