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> Home > Water and soil > The water cycle

The water cycle

Modelling the water cycle and the transport of substances, including exchanges between groundwater and surface water and associated ecosystems.


We need water for drinking, in agriculture, in nature, in industry, in households, for energy and for pleasure. Everyone needs water in the right amounts in the right places. Water flows as surface runoff, in the upper soil layers, in the deeper-lying layers, as well as into watercourses, lakes and the sea, and it transports substances with it. In order to ensure that we can meet all demands for water, even in the future with a changed climate, it is important that we understand the water cycle.

GEUS’ activities in brief

Through hydrological field studies and hydrological modelling, GEUS is building knowledge about the entire water cycle. GEUS makes quantitative statements of Danish water resources, establishes better understanding of the interactions between groundwater and surface water/the sea, models water transport of substances, examines climate change impacts on the water cycle and contributes to climate change adaptation initatives. The outcomes are often used in Danish water resources management. Some activities take place internationally and in connection with capacity building in developing countries.


Water cycle modelling

GEUS models the water cycle in order to quantify both quantity and quality of Danish freshwater resources, quantify the impact of groundwater on surface water/the sea, as well as assess the uncertainties linked to the model's results. GEUS’ focus is particularly at national scale, where GEUS has built a national model, the DK-model; an integrated surface water/groundwater model set up for all of Denmark. This model is being used in connection with Danish groundwater resources management and Danish work on the water plans. Furthermore, the model is also being applied in numerous research projects.


Modelling of substance transport

In connection with efforts to protect groundwater and surface water/the sea against pollution, GEUS is developing models of the transport by groundwater of e.g. nitrates and pesticides. As geology determines flow routes, GEUS' activities at the national scale focus in particular on determining the level of geological detail required to achieve low-uncertainty results. This is a research topic in several projects and is also included in nitrate modelling using the DK-model for national water plans.


Hydrogeological field studies

GEUS undertakes hydrological field studies to determine hydrological parameters, characterise the interactions between groundwater and surface water, as well as between groundwater and saline waters, and to determine flow routes e.g. in connection with substance transport. These field studies are also contributing to the establishment of good water cycle models, because these require a good hydrological understanding of the system and familiarity with the correct parameters.

Climate change impacts on the water cycle and climate change adaptation

GEUS works with hydrological modelling to quantify the impact of climate change on the water cycle, and in order to contribute to climate change adaptation initiatives. For more, see Adaptation to climate change ((LINK)).
The water cycle