Spatially differentiated analyses of agricultural water conservation

Background and Objective

The water status has improved significantly after assessments by experts in the past decades. However, further efforts are necessary to achieve the established water protection goals.

In particular the groundwater pollution from diffuse sources is significant.

The inventory in the Weser river basin showed that only 19% of the surface water bodies are in good condition or are likely to achieve this.

Main reasons that target values ​​are exceeded are mostly nutrient inputs from agricultural land use. The water management in the river basin district Weser is therefore urgent to reduce the emission of agricultural nutrients.

The overall objective of the project is to develop a universal model approach for the entire river basin to evaluate and analyse the nutrient situation. It supports a transnationally coordinated management plan and the associated program of environmental measures. With this model approach integrative analysis of the status quo and of measures are possible. We take into account all the significant scientific and socio-economic factors. We develop strategies on this basis, or, as required by the WFD programs, measures for sustainable (agricultural) water protection.

Target Group

policy makers (federal, state, county government); Chambers of agriculture, farm managers, environmental groups, farmers' association, interested public

Approach

To achieve the above objectives, we see the following work steps:

• Merge, update and harmonize a unified data base for each river basin district.
• To couple the Regionalised Agricultural and Environmental Information System for Germany RAUMIS {link: RAUMIS in the model composite} with the large-scale water balance model GROWA and the hydrogeological model WEKU and the MONERIS (Modelling Nutrient Emissions in River Systems).
• Perform model-based analysis of ex-post development and the actual status.
• To consider performing model-based impact analysis of scenarios matched with experts and measures to reduce the pollution of surface waters and groundwater by diffuse nutrient inputs from the agriculture.

Analyse of social and economic consequences for the agricultural sector (income and jobs), such as discussed with experts from the riparian countries of the river basin district Weser.

Data and Methods

As a data base, agricultural statistics and data from the following data surveys were used:

IACS (Integrated Administration and Control System), trade in fertilizers, agricultural accounts, data on climate, topography of, land cover, the water quality of the groundwater and surface water bodies and soil and hydrogeological parameters.

For the analyses in the AGRUM-Weser project we developed and used an interdisciplinary model network, consisting of the regionalised agricultural economics RAUMIS model, the hydrological / hydrogeological models GROWA / WEKU and the nutrient emission model MONERIS.

Results

With the coupling of the models RAUMIS, GROWA, DENUZ / WEKU and MONERIS, we managed to create a model system that is suitable to illustrate the nutrient status of an entire river basin, both realistic and differentiated - in terms of large areas as well as by pathways and necessary actions and to analyze options for appropriate action. We have also made sure that the models can be transferred with relative ease to  other river basins (with available data bases). In addition, the composite model is suitable to analytically accompany the action programs of the catchment areas.

Over the last 15 years we have seen that nutrient balance surpluses are reduced. According to the model calculations, this will continue until 2015. Caused by the residence times of nutrients in the soil and groundwater system, the time needed for improved conditions can differ between the regions. However, in a projection until 2015 under status quo conditions (baseline), if one takes into account delayed effects, neither the goals for groundwater nor for surface water could be achieved for the two studied nutrients, nitrogen and phosphorus.