NaWas - Raab
Sustainable water quality management Raab – Online Monitoring
An effective water quality monitoring has become critical for the management of our water resources and their catchments. Without accurate, intensive and long-term data acquisition, adequate state assessment and evaluation of measures to improve water quality cannot be performed effectively. Field measurements for water quality evaluation depend upon costly, time- and labour-intensive on-site sampling, analysis and data collection, but still the gathered information is often too limited on temporal scale to address water quality problems. In this respect, online monitoring is a useful tool to remotely obtain continuous information on the water quality of surface waters.
Although the benefits of online measurement techniques, e.g. continuous data availability are obvious, the generation of valuable datasets for information gain involve several difficulties. Thus a high-sophisticated data-management is a prerequisite to use the advantages of online monitoring data.
Since March 2006 a water quality monitoring station at a small power station in an Austrian lowland river is operated by Institute of Water Quality (TUW‑IWAG). While in the beginning the station was housed directly in the power station, it is now located in a container nearby. The river water is pumped directly out of the inlet of the power station into a flow through tub equipped with numerous single- and multi-parameter probes.
As a matter of fact, the continuous measurement of several parameters with different probes results in huge data amounts. To gain a verified and manageable dataset for data interpretation, several intermediate steps have to be implemented, i.e. conversion of measurement signals, data processing, data storage, data plausibility check and data validation. These tasks are performed by the toolset iTUWmon©, which is a measurement network platform technology developed at the TUW‑IWAG, consisting of software components for data acquisition, data processing, storage and export, based on industrial hardware for data transport. To ensure a system-wide comparability of data, proper time synchronisation was one of the fundamental tasks during system design. A further step comprehends the automatic plausibility check of the stored data. The values of a probe are cross-checked with statistical coefficients of the underlying long-term measurements. Data of several redundant probes are matched and finally uncertain data are flagged also by integration of metadata. To meet these requirements, the data sets are converted into an open, comprehensive data format for combining different measurement values from different measurement hardware manufacturers. Based on the compacted data streams additional processing steps for data viewing, automatic data publication and alarming in case of failures are implemented. A sort of service-oriented system architecture is established. In total, these system allows the transformation from data into information, enabling further scientific investigations, e.g. surveillance of immission thresholds, observation of dischargers’ situation, monitoring of diffuse pollution or efficient calculation of transported loads.