Continuous Water Quality Monitoring – How to survive extreme events

Roman Kadluczka and Melody Wu - Manly Hydraulics Laboratory , 17 December, 2020

Continuous (time series) water quality monitoring stations are established to assess variations in the quality of surface water. Near real-time water quality data and easy to understand information presentation can help water authorities and the community to make informed water related decisions. However, with an increased risk of extreme weather events in Australia, like extended drought or extreme precipitation events, both capturing water quality data and presenting information is challenging. We explore these challenges in water supply tidal pools, where the transitional zone between the freshwater and saltwater impacts the extraction of water for irrigators, industry and local water supplies, especially during critical water shortage situations.

Extreme event water quality monitoring requires sound engineering and scientific practice. The overall design of the water quality monitoring stations and sound maintenance activities are key to enable a station to adequately measure and maximise quality data capture. The station’s sensor selection, frequency of the sensor calibration, and field servicing and verification program, should be based on the objectives of the water monitoring program and recognition of environmental extremes during its life.

Most of the common continuously monitored water quality parameters like temperature, pH, and dissolved oxygen usually remain within a reasonable working range during events. However, there can be drastic changes in electrical conductivity (salinity) readings during both dry and wet weather events, especially at the tidal interface. A suitable conductivity data quality coding system is required to cover freshwater, brackish water and saltwater and should be determined according to the monitoring program’s objectives in consultation with the client and
its end users.