One hundred years of hydrology

Knowledge of our watercourses is currently a major focus - particularly considering increased flood risks in a changed climate, as well as new EU directives on good aquatic environments. This year SMHI is celebrating the 100th anniversary of hydrology.

Hydrology is a hundred years old and more relevant than ever. Energy, overfertilisation, floods, a good aquatic environment and water resources - these are just a few examples of how knowledge of our lakes and watercourses is a very vital social issue. But hydrology has always played an important role over the last 100 years, although the actual issues have varied.

"Hydrology functions best in combination with other sciences. The needs of the future will also demand even more from this collaboration," comments professor Sten Bergström at SMHI.

"Many of our current successes are based on our combination of hydrology, oceanography and meteorology, as well as close cooperation with other parts of society. For instance, the creation of a common research department for all of SMHI has provided an excellent basis for working on climate change issues."

The history of hydrology goes back a long way. In the nineteenth century, it was mainly an issue for agriculture, as lakes were lowered to make more land available for agriculture. At the start of the twentieth century, interest in the expansion of water power grew, leading to a demand for new information on water flows and heights of falls, often in remote parts of the country.

Hydrografiska Byrån (The Hydrographic Office) was founded in 1908, its primary focus being surveying Swedish watercourses. Eleven years later its activities were merged with those of Meteorologiska Centralanstalten (The Central Meteorological Institution). The name SMHI was adopted in the mid 1940s. In the 1980s, oceanography formally became part of the institution´s work, but measurements in Swedish coastal areas commenced back in the 1960s.

Measurements of water levels and flows have always been an important basis in hydrology. But ideas about being able to calculate and forecast flows at different times gradually developed. This became possible with the introduction of computers in the 1970s. SMHI´s first hydrological calculation model, the HBV model, was introduced in 1972 and since then has been a well-used tool, both in Sweden and internationally.

During the 1980s, a number of floods occurred and the failure of the dam at Noppikoski in 1985 became a strongly symbolic event. A modern hydrological forecast and warning service was set up, while physical planning and flood risks started to become important social issues.

The 1980s also saw newly-awakened interest in environmental issues, such as acidification and overfertilisation of lakes, watercourse and coastal areas. Widespread algal blooms in the Baltic Sea emphasised the problem of emissions. Water environment issues will also remain high on the agenda, particularly against the background of the new EU water directives, with major demands for national environmental reporting.

When Hydrografiska Byrån was set up one hundred years ago, the needs were completely different to today, but then, as now, knowledge was based on historical series of measurements.

"Long time series of water data are invaluable, as they provide us with a perspective on extreme events and help us to plan with adequate safety margins. We still need unbroken and homogenous series of high-quality data for future generations. We also need to safeguard continued active knowledge gathering to meet future needs," says Gunlög Wennerberg, hydrologist at SMHI.

Around 60 hydrologists currently work at SMHI, within the fields of forecast and warning services, research, consultancy assignments, observations and measurements.