Showing papers by "Zbigniew W. Kundzewicz published in 2004"

Change detection in hydrological records— a review of the methodology

Abstract: General guidance is offered as to the methodology of change detection in time series of hydrological data, embracing stages such as preparing a suitable data set, exploratory analysis, application of adequate statistical tests and interpretation of results. Although the paper cannot go into full details of the many existing tests, it gives an easy-to-follow overview, offering practical hints and describing caveats and misconceptions. It serves as a refresher, raising attention to essential things that have often been ignored. A particular recommendation of the paper is that greater use of distribution-free testing methods, particularly resampling methods, should be made. These methods are recommended because they are particularly suited to hydrological data, which are often strongly skewed (non-normal), seasonal and serially correlated. Resampling techniques are flexible, robust and powerful, and require only minimal assumptions to be made about the data.

Change detection in hydrological records—a review of the methodology / Revue méthodologique de la détection de changements dans les chroniques hydrologiques

Abstract: General guidance is offered as to the methodology of change detection in time series of hydrological data, embracing stages such as preparing a suitable data set, exploratory analysis, application of adequate statistical tests and interpretation of results. Although the paper cannot go into full details of the many existing tests, it gives an easy-to-follow overview, offering practical hints and describing caveats and misconceptions. It serves as a refresher, raising attention to essential things that have often been ignored. A particular recommendation of the paper is that greater use of distribution-free testing methods, particularly resampling methods, should be made. These methods are recommended because they are particularly suited to hydrological data, which are often strongly skewed (non-normal), seasonal and serially correlated. Resampling techniques are flexible, robust and powerful, and require only minimal assumptions to be made about the data.

Floods in the IPCC TAR Perspective

Abstract: Recent floods have become more abundant and more destructive than ever in many regions of the globe. Destructive floods observed in the 1990s all over the world have led to record-high material damage, with total losses exceeding one billion US dollars in each of two dozen events. The immediate question emerges as to the extent to which a sensible rise in flood hazard and vulnerability can be linked to climate variability and change. Links between climate change and floods have found extensive coverage in the Third Assessment Report (TAR) of the Intergovernmental Panel on Climate Change (IPCC). Since the material on floods is scattered over many places of two large volumes of the TAR, the present contribution - a guided tour to floods in the IPCC TAR – may help a reader notice the different angles from which floods were considered in the IPCC report. As the water-holding capacity of the atmosphere grows with temperature, the potential for intensive precipitation also increases. Higher and more intense precipitation has been already observed and this trend is expected to increase in the future, warmer world. This is a sufficient condition for flood hazard to increase. Yet there are also other, non-climatic, factors exacerbating flood hazard. According to the IPCC TAR, the analysis of extreme events in both observations and coupled models is underdeveloped. It is interesting that the perception of floods in different parts of the TAR is largely different. Large uncertainty is emphasized in the parts dealing with the science of climate change, but in the impact chapters, referring to sectors and regions, growth in flood risk is taken for granted. Floods have been identified on short lists of key regional concerns.