Eight years experience with the Elbe estuary environmental survey net

The company ME MEERESTECHNIK-ELEKTRONIK GmbH has operated since 1985 a network for the monitoring of environmentally relevant water quality parameters in the vicinity of the Brokdorf Nuclear Power Plant (Germany). For the last 8 years, interrupted only by ice periods, at 10 stations every ten minutes precision registrations of water temperature, dissolved oxygen content, electrical conductivity, pH, water level and current velocity are performed. During the long-term operation of the survey network, ME could accumulate extensive experience in long-term registration of hydrographical parameters. Based on the evaluation of all the service activities and the data sets, particular information concerning the life-time and service intervals of the sensors could be gained. The probability of sensor failure caused by biological fouling was determined quantitatively. Based on the experiences with the operation of the Elbe estuary survey net, conclusions are drawn for the further improvement of the long-term stability of hydrographical sensors as well as the optimization of the cost-intensive surveillance and maintenance activities