Monitoring Groundwater for the Effectiveness of Action Programs in Denmark, 1988-2009
Geological Survey of Denmark and Greenland
The National Monitoring and Assessment Programmed for the Aquatic and Terrestrial Environment (NOVANA) was established in 1987 when the first Action Plan for the Aquatic Environment was passed by the Danish Parliament. The core objective of the monitoring program was to follow the effects of different measures to mitigate nutrient impacts on the environment. Measures included enhanced wastewater treatment, stricter rules on manure storage, optimization of manure application/plant uptake, an increase of green fields, fallowing, raised levies on inorganic fertilizers, etc. During the years, further Action Plans have been introduced with the aim of meeting national goals as well as the requirements of the EU Directives and other international agreements. Consequently, the monitoring program and objectives have been adjusted regularly. Currently the whole program is undergoing a revision to agree with the monitoring strategies of the EU Water Framework Directive. The NOVANA program covers all aquatic environments, such as agricultural catchments, streams, lakes, groundwater, coastal and marine waters plus air and terrestrial environments. The program is carried out in cooperation between the Environmental Protection Agency and the Agency for Spatial and Environmental Planning, the Geological Survey of Denmark and Greenland (GEUS), the National Environmental Research Institute (NERI), and seven Environment Centers under the Agency for Spatial and Environmental Planning. The groundwater part of the monitoring program focuses on assessing the status and development of groundwater quantity and quality. It consists of a network of approximately 1,500 permanent monitoring points located in 73 dedicated groundwater monitoring areas, each covering a catchment area of a drinking water abstraction well (Figure 1). Each area has about 24 screens, from which a broad range of quality aspects of the aquifers, from the youngest upper groundwater to the deeper layers used for abstraction can be accessed. The areas are representative for the variation in geological setting and land use in Denmark. In addition, detailed monitoring is carried out in five small agricultural catchments, with focus on conventional agricultural practices, and fluxes of nutrients in soil and the uppermost groundwater. Time series of approximately 20 years are now available for nitrate and other major ions as well as pesticides, trace metals, and a range of organic pollutants. Groundwater dating with CFC in the monitoring areas has proved to be a strong tool when interpreting the collected data. An example is given in Figure 2, where nitrate is linked to the time of the groundwater formation as found by CFC and compared to agricultural use of inorganic nitrogen fertilizers. The reduction in use of inorganic fertilizers is an effect of the Action Programmes. The average nitrate concentration in Danish groundwater shows a downward tendency during the last years of monitoring. Future focus is on statistical trend analyses, as prescribed by the EU Groundwater Directive.