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​Annual report 2015 - Water resources

Knowledge to optimise management of Danish water resources
International research evaluation
The Board of GEUS continuously evaluates the quality of the institution's scientific work. In 2015, an international panel recommended by the Danish Council for Independent Research probed the quality of GEUS' research on water resources. In its assessment, the panel reported that GEUS' research is of high quality. Furthermore, the panel emphasised as an important strength that GEUS successfully applies its hydrological model as a tool to integrate and work across research topics such as groundwater monitoring, groundwater mapping, the water cycle, water quality, water and environmental technology, and management of water resources. The Board has subsequently expressed its satisfaction with the results of the assessment and stressed that GEUS has a strong portfolio of research projects in the water resources area, and that these are extremely visible internationally. The Board was also pleased with the panel's assessment of employee motivation and GEUS' research facilities. GEUS has subsequently prepared an action plan following up on the recommendations in the assessment report. The plan has been endorsed by the Board.

The Minister for Energy, Utilities and Climate, Lars Christian Lilleholt, has noted the report and said: It is extremely satisfactory that GEUS has received such a positive assessment in an area of such significance for the Ministry, GEUS and society in general.

National nitrogen model
GEUS, the Danish Centre for Food and Agriculture (DCA) and the Danish Centre for Environment and Energy (DCE) at Aarhus University developed a national nitrogen model in 2015 which can calculate in more detail and more accurately the amount of nitrogen being leached into coastal waters in Denmark each year and how much is being removed before it ends up in the sea. Nitrogen leaching from the root zone of farmland and other areas is transported via drainage systems and groundwater to watercourses, lakes and wetlands, from where it flows onward to the fjords and coastline. During this transport, some of the nitrogen is removed from and retained in the root zone, subsurface or in surface waters. This retention of nitrogen depends on the natural conditions between the farmland and the coast and, therefore, varies from place to place.

The model divides Denmark into small areas of just 15 km2 from where the transport and retention of nitrogen from the farmland to the coast are calculated. Three sub models have been coupled to achieve this: A sub model for nitrogen leaching from the root zone developed by DCA, a sub model for water flows and nitrogen retention in the groundwater zone developed by GEUS, as well as a submodel for contributions of organic nitrogen and nitrogen retention in surface waters, i.e. lakes, watercourses and wetlands, developed by DCE. Development of the model applies the greatest possible national measurement data basis, which includes data from more than 300 watercourse stations, e.g. collected under the national programme for monitoring the aquatic environment and nature (NOVANA). Furthermore, the model-calculated leaching is based on measurements of leaching from a large number of farmland trials and monitoring under the LOOP land-monitoring programme. Development of the model was commissioned by the Danish Environmental Protection Agency, the Danish Nature Agency and the Danish AgriFish Agency.

Better assessment of spatial patterns from hydrological models
Water scarcity, over-exploitation and pollution have increased pressure on the world's water resources. This threatens the living conditions of people, animals and plants and limits agricultural production. Water resources management has primarily been based on knowledge from hydrological models which produce calculations on catchment-area scale and there is an urgent need to develop these models further so that they can meet the demands in modern water resources management about knowledge of water flows and substance transport in small areas within a hydrological catchment area. GEUS is developing new methods which use satellite data to improve calculations in high spatial resolution with advanced hydrological models.

This is taking place under the SPACE project aimed at developing methods for spatial calibration and validation of grid-based hydrological models. This work covers mapping hydrological parameters on the basis of satellite data, such as water content in the soil and evaporation, as well as developing new statistical evaluation criteria to handle spatial patterns. For the methodology development, data from the two hydrological test areas in the Skjern River catchment area and Wüstebach in Germany are used. Researchers have been collecting large quantities of hydrological field data from these areas for several years. Finally, the SPACE project will use satellite data to evaluate the results of the hydrological calculations performed using GEUS' national hydrological model. The SPACE project is financed by the VILLUM FONDEN Young Investigator Programme.

Large-scale modelling of saltwater intrusion in groundwater
Saltwater intrusion in groundwater reservoirs along coasts is a growing problem which is threatening drinking water supply in many places. The problem could grow worse with expected rising sea levels in the future. Together with its partners from Aarhus University and the University of Copenhagen in Geocenter Denmark, GEUS is carrying out a project studying how past and future sea levels have and will affect the intrusion of seawater in low-lying coastal areas. The studies are focussing on the westernmost part of Sønderjylland towards the Wadden Sea, an area which is sensitive to saltwater intrusion and where Denmark is likely to experience the largest seal-level increase in the future.

Researchers want to estimate the saltwater intrusion using 3D geological and hydrogeological modelling. Saltwater intrusion depends on the relative increase in sea level and on the geology of the coastal area. However, it also depends on prehistoric groundwater flow, and researchers therefore want to include palaeoglaciological parameters such as the history and thickness of Ice Age ice sheets, subglacial groundwater flow, and groundwater age in their modelling. Finally, the researchers will estimate future saltwater intrusion based on scenarios for relative sea-level change.

In 2015, a 3D geological model was developed for Sønderjylland to serve as the basis for the calculations in the hydrogeological model, being developed. Furthermore, samples from wells in the area were collected for chemical surveys and age-determination of the groundwater. Preliminary results suggest that the deep groundwater in the central part of Sønderjylland is very old. The project is the first in Denmark to examine saltwater intrusion in coastal groundwater reservoirs on a large scale and within a multidisciplinary framework which combines geophysics, geology, groundwater dating and 3D geological and hydrogeological modelling. The project is receiving financial support from Geocenter Denmark.
Annual report 2015 - Water resources