L-MOMENT RATIO MAPS OF ANNUAL PEAK FLOWS IN TURKISH RIVERS

摘要

This study aims to estimate the probability distribution for peak flows using L-moment ratio maps for a study area without any flow measurements. In flood frequency analysis, the determination of an acceptable design criterion depends mostly on the probability distribution of flood. One of the most common methods for choosing the best-fit probability distribution is the L-moment ratio diagram. Lmoment ratio diagrams use the sample estimates of L-moment ratios and compare them with the theoretical L-moment ratios of certain probability distributions. In this study, L-moment ratios of 319 flowgauging stations are calculated for annual peak flows of Turkish rivers. The peak flow series of 264 gauging stations are used to prepare L-moment ratio maps and, the L-moment ratios of 55 stations are saved for validation. The spatial variability of the L-moment ratios is presented in the L-moment ratio maps. Validation results show that the maps successfully represent the L-moment ratios. With these maps, the drawbacks of using point information in projects are avoided. In a project area with no observations or data, related maps are used to estimate the L-moment ratios, which are then integrated into the L-moment ratio diagrams for determining the best-fit frequency distribution models of peak discharges to provide a robust basis for flood frequency analysis.