Regionalization and spatial changing properties of droughts across the Pearl River basin, China

In frequency analysis for droughts, the absence of lengthy records usually limits the reliability of statistical estimates. To overcome this limitation, a “regional” analysis approach is often used. Hydrological events typically have multivariate characteristics; therefore it is logical to jointly consider these characteristics when carrying out a multivariate regional frequency analysis for these events. This study presents a method for regional frequency analysis in the Pearl River basin using the multivariate L-moments homogeneity test. Results indicate that the Pearl River basin can be categorized into five homogeneous regions in terms of drought variation, and the Plackett copula fits well for all of the homogeneous regions. The frequency analysis of all sites in each homogeneous region shows that the Pearl River Delta is characterized by a high drought risk, while a relatively lower drought risk in the west and northeast parts of the Pearl River basin. Results of this study will be useful for basin-scale water resources management across the Pearl River basin.