Statistical methods for performing hydrological analyses have a long history and are still an intense research topic. They have proved to be useful in many applications and case studies, and their effectiveness for describing hydrological processes has underlined the complexity of the hydrological systems, pointing out the ineffectiveness of purely deterministic models. In the last years, tools, approaches and procedures related to several statistical sub-topics have increased fast, as well as the development of commercial and free software and routines. Also, there are more than 100 international journals on statistics and more than 40 journals that accept contributions on statistical hydrology. As a result, there are many available potential statistical approaches for dealing with a specific hydrological problem, while the suitable use of these new and updated methods is essential for hydrological studies.
Under these premises, the Statistics in Hydrology (STAHY) Working Group was launched during the XXIV IUGG General Assembly in 2007, with the aim of offering a focal point for hydrologist who use statistical tools and of being updated on recent developments on their research fields. STAHY has since become an association of talented and innovative scientists, who have worked together to develop several initiatives and the STAHY portal (www.stahy.org). During the XXV IUGG General Assembly the STAHY-WG was transformed into the International Commission on Statistical Hydrology (ICSH-IAHS) in order to provide a more permanent contribution to the scientific community. Nowadays, the Commission is led by ICSH officers Ashish Sharma, Salvatore Grimaldi, Elena Volpi, Yuanfang Chen, Krysztof Kochanek and Ebru Eris.