Research and development within hydrology
SMHI has a long tradition of operational hydrological modelling including forecasts of water discharge, fire hazard, design of dams and dam regulation routines, flood risk, water quality and substance transport and the effects of climate change on hydrology and water quality.
The hydrological research unit is engaged in numerous research projects, commissioned work and continuous development of the SMHI work-flow for hydrological forecasts and assessments. The work is often user-driven and performed in collaboration with external partners in Sweden, Europe or other parts of the world.
In addition, we produce open data from our computational systems and open source codes for hydrological modelling. The unit also has a number of specific scientific focus.
The hydrological research unit has commissions at national and international levels, including IAHS, International Association of Hydrological Sciences, NHF, Nordic Association of Hydrology and SHR, The Swedish Hydrological Council. –
Open data – World wide hydrological predictions
Scientific publications from SMHIs hydrological research unit
We publish our research in international peer-reviewed journals and in SMHI reports. The two most recent publications are shown below.
Sveriges hydrologi i ett förändrat klimat
Anna Eklund, Katarina Stensen, Marie Bergstrand, Anna Åkesson, Anna Engblom, Ola Pettersson, Johan Temnerud, Jan Pietron, Johan Södling, Aino Krunegård
In: Hydrologi
2026
Abstract
We are experiencing very rapid climate change. Humans have warmed the Earth’s climate, primarily through emissions of greenhouse gases. In Sweden, both temperature and precipitation have increased, while the number of days with snow cover has decreased. This in turn affects runoff and water flows. The changes vary between different times of the year and between different parts of Sweden.
This report presents results from calculations of the water balance for the normal periods 1991–2020 and 1961–1990 on a general scale. The concept of water balance used here implies that all precipitation falling over an area either evaporates or flows into a watercourse. In equation form: precipitation = evaporation + runoff. If the water balance is calculated over a longer period, storage in snow, lakes, soil, or groundwater can be assumed to be negligible.
The modeled mean annual precipitation is highest in the western parts of the country, while the lowest precipitation is found in the southeastern and northernmost parts. Evaporation is greatest in the western parts of Götaland and Svealand and lowest in the northern mountain regions. Modeled runoff, which is the difference between precipitation and evaporation, varies considerably across the country. Annual runoff is highest in the mountain regions and lowest in the eastern parts of Götaland and Svealand.
From the normal period 1961–1990 to 1991–2020, both precipitation and evaporation have increased in large areas of the country. Annual mean runoff has also increased in most parts of the country, however - decreased runoff is observed in eastern Svealand and parts of eastern Götaland.
The report also provides an overview of how and why Sweden’s hydrology has changed and is expected to change in the future.
Översvämningshändelser i Sverige
Klara Lindqvist, Merle Liebenehm-Axmann, Julia Zabori, Shirin Karimi, Göran Lindström, Niclas Hjerdt
In: Hydrologi
2026
Abstract
Flood events recorded by the Swedish Transport Administration and the Swedish CivilContingencies Agency in recent decades have been analysed to create a betterunderstanding of flood problems in Sweden and to guide the development of the warningservice. The results show that floods are most common in the summer and in denselypopulated areas, and usually occur far from major rivers and lakes. An overwhelmingmajority of the events also occurred without any warning criteria being exceeded, either inmeteorology or hydrology, and only a minority of the events were therefore preceded byany warning. To improve the warning service for flood events, it is recommended to (1)develop routines for weighing risk factors from both meteorology and hydrology in futureinterdisciplinary flood warnings, (2) place greater focus on runoff calculations as a riskfactor, especially with short time steps and in densely populated areas, and (3) supplementthe current methodology for evaluating warnings to utilize reported flood events from theSwedish Transport Administration, the Swedish Civil Contingencies Agency or othersources.
Research news
SMHI supports the development of a hydrological forecasting and warning service in Estonia
SMHI has started a new collaboration with the Estonian Environment Agency (ESTEA) to support the development of a national, operational hydrological forecasting and warning service in Estonia.
A strategic tripartite partnership to improve flood forecasting in West Africa and the Sahel
The United Nations Development Programme (UNDP), the AGRHYMET Regional Climate Center for West Africa and the Sahel (AGRHYMET CCR-AOS) of the Permanent Interstate Committee for Drought Control in the Sahel (CILSS), and the Swedish Meteorological and Hydrological Institute (SMHI) have established a strategic tripartite ...
Flood warning system in place in Denmark – successful collaboration between DMI and SMHI
For three years, SMHI has supported our sister authority DMI in Denmark in developing a Danish warning system for flooding in lakes and rivers. The initiative has now reached a major goal with the launch of a system that has already been useful in connection with the extreme rain that occurred in July 2025, just weeks ...