H. Behrendt

Ensemble modelling of nutrient loads and nutrient load partitioning in 17 European catchments

An ensemble of nutrient models was applied in 17 European catchments to analyse the variation that appears after simulation of net nutrient loads and partitioning of nutrient loads at catchment scale. Eight models for N and five models for P were applied in three core catchments covering European-wide gradients in climate, topography, soil types and land use (Vansjø-Hobøl (Norway), Ouse (Yorkshire, UK) and Enza (Italy)). Moreover, each of the models was applied in 3-14 other EUROHARP catchments in order to inter-compare the outcome of the nutrient load partitioning at a wider European scale. The results of the nutrient load partitioning show a variation in the computed average annual nitrogen and phosphorus loss from agricultural land within the 17 catchments between 19.1-34.6 kg N ha(-1) and 0.12-1.67 kg P ha(-1). All the applied nutrient models show that the catchment specific variation (range and standard deviation) in the model results is lowest when simulating the net nutrient load and becomes increasingly higher for simulation of the gross nutrient loss from agricultural land and highest for the simulations of the gross nutrient loss from other diffuse sources in the core catchments. The average coefficient of variation for the model simulations of gross P loss from agricultural land is nearly twice as high (67%) as for the model simulations of gross N loss from agricultural land (40%). The variation involved in model simulations of net nutrient load and gross nutrient losses in European catchments was due to regional factors and the presence or absence of large lakes within the catchment.

Description of nine nutrient loss models: capabilities and suitability based on their characteristics

In EUROHARP, an EC Framework V project, which started in 2002 with 21 partners in 17 countries across Europe, a detailed intercomparison of contemporary catchment-scale modelling approaches was undertaken to characterise the relative importance of point and diffuse pollution of nutrients in surface freshwater systems. The study focused on the scientific evaluation of different modelling approaches, which were validated on three core catchments (the Ouse, UK; the Vansjo-Hobøl, Norway; and the Enza, Italy), and the application of each tool to three additional, randomly chosen catchments across Europe. The tools involved differ profoundly in their complexity, level of process representation and data requirements. The tools include simple loading models, statistical, conceptual and empirical model approaches, and physics-based (mechanistic) models. The results of a scientific intercomparison of the characteristics of these different model approaches are described. This includes an analysis of potential strengths and weaknesses of the nutrient models.

Integrated water resources management in central Asia: nutrient and heavy metal emissions and their relevance for the Kharaa River Basin, Mongolia

Within the framework of Integrated Water Resources Management (IWRM) the nutrient and heavy metal levels within the Kharaa river basin were investigated. By the application of the MONERIS model, which quantifies nutrient emissions into river basins, various point and diffuse pathways, as well as nutrient load in rivers, could be analysed. Despite seasonal variations and inputs of point sources (e.g. Wastewater Treatment Plant Darkhan) the nutrient concentrations in most of the subbasins are on a moderate level. This shows evidence for a nutrient limited ecosystem as well as dilution effects. However, in the middle and lower reaches heavy metal concentrations of arsenic and mercury, which are linked to mining activities in many cases, are a point of concern. Thus measures are necessary to protect the valuable chemical and ecological status of the Kharaa River and its tributaries. As a result of the growing economic pressure Mongolia will enhance the agricultural production by irrigation. Until 2015 about 60% of the agricultural land shall be irrigated. In addition the gold mining activities shall increase by 20% a year. Both sectors have a high demand for water quantity and quality. The model MONERIS allows the assessment of measures which are inevitable to protect the water quality under shrinking water availability.

Rivers of the Central European Highlands and Plains

The ecoregion of the central European highlands and plains is drained by some of the main rivers that flow into the Baltic and North Seas, including the Weser, Elbe, and Oder Rivers. In addition to these rivers, this chapter describes some smaller but peculiar rivers, such as the Em (Sweden), Skjern (Denmark), Spree (Germany) and Drawa (Poland) rivers. The Weser River exhibits a balanced longitudinal sequence of geomorphologically distinctive river sections typical of the Central European Highlands and Plains. The Weser and its tributaries provide important ecological services to society, including drinking water, sewage removal, water for irrigation, cooling water for power plants and industrial facilities, hydropower, habitat for organisms, and recreation and tourism. With a length of 1094 km, the 8th order River Elbe (Czech: Labe) is the third longest river in central Europe (after the Danube and Rhine). The Elbe is often seen as a river still possessing a natural river bed with active flood-plains. The Oder (Polish and Czech: Odra) is the sixth largest river flowing into to the Baltic Sea, with an annual discharge volume of 17.3 km. Being 854 km long, the Oder is the second longest river in Poland (after the Vistula). It has been used early for navigation both in north-south and east-west directions, as it has been connected early with the Elbe catchment via two canals.