Landmarks in the world of water ― memorable attributes and events that are noted and quoted ― often tend to focus on large physical features like the River Amazon and Niagara Falls. Alternatively they feature extremes such as the Pakistan floods of 2010 and the successive droughts in the Horn of Africa. But there are others that are less immediately recognizable, which do not often hit the headlines, e.g. the start of international initiatives, like the International Hydrological Programme in 1975 and the Millennium Development Goals in 2000. Pre-dating these happenings was the launch of the International Branch (or Section) of Scientific Hydrology at the Rome General Assembly of the International Union of Geodesy and Geophysics (IUGG) in 1922, later to become the International Association of Scientific Hydrology (IASH). Here we highlight some of the main achievements of what is now the International Association of Hydrological Sciences (IAHS) ― the foremost international learned society dealing with the pressing problems of water resources, floods, droughts, water pollution, erosion, etc., together with the science and technology to address them.

Today, the Association is a lively non-profit making international non-governmental scientific organization. It started from small beginnings in 1922 as a gathering of a few scientists and engineers from about half a dozen European countries ― probably none of those present would have called themselves a hydrologist—and now has more than  5500 individual members, 10 commissions and three working groups. What was in the minds of these delegates when they established the Hydrology Branch of IUGG and in the thoughts of those who made it into the Association in 1930 is not recorded in the proceedings. However, there is little doubt that they would be amazed at the extent and depth of the Association’s activities as the 21st century unfolds. Then the Association’s assemblies attracted less than 100 participants, with little happening in the years intervening. Now, IAHS is a vibrant international community of hydrologists. Furthermore the Association shares activities in a number of fields: with several IUGG Commissions, with some of the other seven Associations in the IUGG family, and also with a number of associations outside IUGG, including the International Association of Hydrogeologists (IAH) and the International Association of Hydro-Environment Engineering and Research (IAHR). These linkages demonstrate that IAHS has a broad base for its science activities. In addition, there is also the intergovernmental world where IAHS has interests in common with several UN bodies; particularly with the United Nations Educational, Scientific and Cultural Organization (UNESCO), the World Meteorological Organization (WMO) and the International Atomic Energy Agency (IAEA) and also with UN Water. Indeed IAHS, through the efforts of Professor L. J. Tison (Secretary General 1948–1971), helped launch the UNESCO and WMO programmes in hydrology. Professor Tison is recognised as one of the three “fathers” of the International Hydrological Decade (IHD) which preceded the last International Hydrological Programme (IHP), and he was very influential in establishing the WMO Commission on Hydrological Meteorology, the forerunner of today’s Commission on Hydrology. These and other facts and figures are captured on the Association’s website www.iahs.info, together with a wealth of information about its current activities.

There have been so many changes over the 92 years of the Association’s existence to facilitate its business, we tend to forget them. The ease of travel nowadays allows meetings to take place virtually anywhere on the planet, whereas they were all in Europe during the early years. Over the last decade IAHS and its Commissions have convened 6–8 conferences a year on specific topics, in addition to the Scientific Assemblies and General Assemblies within IUGG Assemblies. The tradition of publishing Proceedings and Reports of IAHS (Red Books) which commenced in 1924 at the Madrid General Assembly, has continued to the present with IAHS Publication 362 being the most recent. Sediment dynamics, land subsidence, forest hydrology, isotopes, groundwater management ― are amongst the themes of recent proceedings. In addition there are the Special Publications Series (Blue Books), Benchmark Series and the Hydrological Sciences Journal (HSJ). HSJ was originally published three times a year from 1953 as the Bulletin of IASH; it became HSJ in 1982 and now has 12 issues a year, with more than 1000 pages per volume. These publications can be ordered at the Association’s online bookshop while members in poorer countries have free online access to HSJ. IAHS Press was established at Wallingford, UK, in 1972 and its four staff probably produce more scientific publications dealing with hydrology and water resources than any other publisher. None of the other IUGG associations have such an extensive publications programme.

The different forums offer means for discussion, review, publication and dissemination of the results of research and they help to direct efforts to areas where problems are proving more intractable. They stimulate educational outreach and the transfer of knowledge which can be applied in planning, development and management of water resources, particularly through the IAHS Task Force for Developing Countries (TFDC). TFDC manages the programme for the free distribution of HSJ, Red Books and other publications to more than 50 libraries in developing countries which has been underway since 1991. IAHS has also been very successful in obtaining funds from a considerable number of donors to support the attendance of members from these countries at IAHS gatherings.

To recognise outstanding contributions to the science and to international hydrology, along with UNESCO and WMO, IAHS awards the International Hydrology Prize annually, and also the Tison Award to young scientists for recording their innovative research in one of the Association’s publications.

Peering into the past through the prism of the science to predict and forecast future events has a well established methodology in hydrology, whereas the means for predicting the path of the science itself remain rudimentary. Nevertheless the Association has, on several occasions, taken a glimpse at what the coming years may hold. For example, at Rome in 1987 the Water for the Future Symposium looked at the Thrust of Thought in Contemporary Hydrology and New Techniques in Data Capture. Twice since 1982 the minds of a selection of the younger members of IAHS have been exercised to consider the future of hydrology. Most recently, the Hydrology 2020 Working Group, reported its findings in 2006 (Hydrology 2020: An Integrating Science to Meet World Water Challenges, ed. by T. Oki, C. Valeo & K. Heal, IAHS Publ. 300). In a similar way the 10-year Predictions in Ungauged Basins (PUB) initiative (2002-2012), was aimed at a future where the ultimate goal in hydrology would be achieved ― the hydrological prediction of ungauged basins and reduction of the associated uncertainty. The next hydrological decade of Panta Rhei initiative will lead the Association up to its centenary in 2022.

John C. Rodda