In-line river monitoring--new challenges and opportunities.

Water management becomes a complex issue when considering the large number of water-rights-of-use like drinking water production, recreation, receiving water, transport on and ecological quality of the water bodies. Recent changes in the legal requirements concerning water management on European scale (EC Water Framework Directive, 2000/60/EC) highlighted the need for appropriate means for monitoring water quality and exchange of water quality data. Indirect measurement of water quality using surrogate parameters (chemical and physical-chemical parameters) can be automated at a high accuracy level. This was shown over the past years by national and international research projects. In 2001 such a research project has started in Austria focusing on the installation and operation of a pilot water quality network, which is suitable for application at several points of interest of water management, i.e. sewer networks, wastewater treatment plants and receiving water bodies. The paper describes the operational problems and experiences of collecting data over a period of one year in the Danube River downstream of Vienna. The sensors are installed in situ, directly in the river, without any bypass system. The first evaluation of the measurements shows that the values are reliable and therefore applicable to further interpretations.