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).

This dataset shows the percentage nitrogen retention in Denmark, i.e. the proportion of nitrogen leached from the root zone that is transformed or retained in the subsurface and surface waters before reaching the coast. Nitrogen retention is calculated using the National Nitrogen Model and represents an average retention for the period 1990–2010. The dataset provides nationwide coverage of spatial variations in nitrogen retention and is used as a basis for assessing nitrogen transport and coastal nutrient loading. The National Nitrogen Model version 2020 is documented in National Nitrogen Model – version 2020, a GEUS special report, including a method report (ISBN 978-87-7871-551-7) and an appendix (ISBN 978-87-7871-552-4), both available from GEUS (in danish).