This repository contains three national nitrogen retention maps for Denmark and associated uncertainties. “TotalRetention_regioner.tif” is the total retention (nitrogen removal) from the source location to the coast, “Grundvandsretention_regioner.tif” is the retention during transport in the groundwater and “Overfladevandsretention.tif” is the retention in the surface water system, i.e. streams, lakes, wetlands and inundated areas. The maps for the total and groundwater retention are aggregated from a 100 m grid into regions with a minimum size of 50 ha based on similarity between neighbouring grids. For surface water, the spatial resolution is defined as the contribution catchment discharging to the individual retention environments, e.g. a lake catchment. The total retention is supplemented by two maps “TotalRetention_usikkerhed_regioner.tif” showing the uncertainty in the total retention estimated for each region and “TotalRetention_standardafvigelse_regioner.tif” displaying the standard deviation between the individual grids within each region. All maps are calculated using data for the period 2000 – 2021. The nitrogen retention maps have been developed in a collaboration between GEUS and Aarhus University. (2025-08-29).

Documentation includes appendicies: National kvælstofmodel - version 2025. Udvikling af nye kvælstofretentionskort. Bilagsrapport. De Nationale Geologiske Undersøgelser for Danmark og Grønland. GEUS særudgivelse. ISBN 978-87-7871-620-0, https://doi.org/10.22008/gpub/38955.

Højberg, A.L., Thodsen, H., Børgesen, C.D. (red.) Andersen, A.H., Andersen, L.T., Audet, J., Bach, E.O., Christiansen, D.T., Christiansen, D.A., Conde, J.T., Falk, F.A., Frederiksen, R.R., Giannini-Kurina, F., Gudbjerg, J., Han sen, B., Henri, C.V., Henriksen, E.S., Hermansen, N., Hoffmann, C.C., Høyer, A., Iver sen, B.V., Jakobsen, R., Jørgensen, M.S., Kim, H., Kjeldgaard, A., Koch, J., Kronvang, B., , Liu, J., Madsen, R.B., Martin, N.L., Molis, M., Mortensen, M.H., Motevalli, A., Muff, E., Møller, I., Ondracek, M., Petersen, R.J., Pugliese, L., Rosenkrantz, A., Sandersen, P., Schneider, R.J.M., Sonnenborg, T.O., Stisen, S., Sørensen, P.B., Thorling, L., Tornbjerg, H., Troldborg, L., Uldall-Jessen, L., Voutchkova, D., Aamand, J.. 2025. National kvæl stofmodel - version 2025. Udvikling af nye kvælstofretentionskort. Metoderapport. De Na tionale Geologiske Undersøgelser for Danmark og Grønland. GEUS særudgivelse, ISBN 978-87-7871-619-4, https://doi.org/10.22008/gpub/38954 doi: 10.22008/gpub/38954.