IWRA World Water Congress 2008 Montpellier France
1. Water availability, use and management
Research Centre Juelich, Institute for Chemistry and Dynamics of the Geosphere, Wilhelm-Johnen-Str., 52425
Jülich, Germany, Phone: ++49 (0) 2461 61 3262, Fax: ++49 (0) 2461 61 2518, E-mail: email@example.com
Diffuse nitrate pollution, river
basin management, EU - Water Framework Directive, multicriteria assessment, nitrogen reduction measures
The implementation schedule for the EU water framework directive requires the
establishment of river basin district management programmes until 2009. In Germany, the reduction of nitrogen load
into groundwater, mostly caused by diffuse emission from agriculture, is one of the most challenging tasks. Within the
EU-Life project WAgriCo (Water Resources Management in Cooperation with Agriculture) nitrogen management
options adapted to hydrological and agro-economic site properties are developed and implemented for three pilot
areas in the Federal State of Lower Saxony using new participation approaches and technologies suitable for
programmes of measures to reduce diffuse pollution from agriculture.
The definition of environmental
objectives is an indispensable precondition for assessing the required amount and efficiency of water protection
measures. In the WAgriCo-project a nitrate concentration in percolation water of 50 mg/l has been defined as the
environmental target for groundwater protection. This value, however, is regarded as an average for a larger area
defined by the groundwater bodies and their hydrogeological subdivisions rather than as for each individual site. For
each of these subdivisions, the current pressure of agriculture to groundwater is quantified. For the evaluation of the
amount and efficiency of certain water protection measures, the required reduction of N-surpluses to accomplish the
environmental target needs to be quantified, using the current status as a reference.
macroscale agroeconomic-hydrogeological model is used to simulate the interactions between agricultural practice,
nitrogen surpluses and the nitrogen flow through the soil and aquifer to the outflow into surface waters. The actual
nitrate concentrations in percolation water are calculated for the entire Federal State of Lower Saxony on a 50 x 50
m resolution considering site-characteristics, N-surpluses, water balance and denitrification in the soil. The tolerable
N-surpluses needed to meet the environmental target are quantified as averages for each of the hydrogeological
subdivisions by “inverse” calculation using this model system. The required reduction of N-surpluses can then be
estimated by comparing the tolerable N-surpluses to the actual state of nitrogen emission.
the WAgriCo project a number of measures and measure combinations with detailed management prescriptions
were selected and evaluated with regard to its potential N-surplus. By using the nitrogen export model their effects
are assessed with respect to the nitrate leaching to groundwater and surface waters. The measures effectivenesses
and its needs are evaluated area-differentiated for each of the areas considered.