Lake Ecosystem Research New Zealand
Traditional water quality monitoring methods often fail to properly characterise important lake processes and indicators of lake water quality. Recent advances in sensor technologies and telemetry have enabled the measurement of water quality at frequencies not previously possible, by allowing near-real-time access to continuous high-frequency in-lake measurements. High-frequency monitoring buoys enable better understanding of processes that affect lake health, including temperature stratification patterns, oxygen depletion from bottom waters, algal species succession, sediment resuspension and water clarity. These data help to evaluate the effectiveness of restoration measures undertaken in lakes and catchments.
LERNZ researcher Chris McBride has developed a network of 19 solar-powered water quality monitoring buoys around New Zealand. Managed by Limnotrack, client stakeholders include Fish and Game, District and Regional Councils, energy companies and private trusts and landowners. The buoys measure water temperature, chlorophyll and phycocyanin (cyanobacteria) fluorescence, dissolved oxygen, turbidity, pH, and meteorological variables. Data are transmitted to a database and web interface every 15 minutes.
In addition to the standard fixed sensor buoys, newly developed vertical profiling buoys use an electric winch and armoured data cable raise and lower a water quality sensor package throughout the water column many times per day. This provides greater resolution of vertical bottom oxygen depletion and distribution of algae. Real-time data from the Te Arawa lakes monitoring buoys can be view on the Bay of Plenty Regional Council's Environmental Data Portal.
Schematic of vertical profiler buoy deployment
Limnotrack lake buoy monitoring network
Lake Rotorua real-time monitoring buoy.
Low-cost Arduino equipment customized by EnviroDIY.org provides an accelerating pathway for using high-quality sensors. Initially evolving through a US National Science Foundation funded Critical Zone Observatory at the Stroud Research Centre, the customised Mayfly boards provide a robust, low cost option for sensor stations. A significant advantage is the international non-commercial model complete with a code repository (on Github) and web-enabled cloud upload technology. We have so far demonstrated basic conductivity-temperature-depth and more capable stations with turbidity, dissolved oxygen, temperature and conductivity, and telemetered data deployed at streams of interest flowing in the Rotorua Te Arawa Lakes. Ongoing science-driven development is focussed deploying a growing array of stations with varying capabilities dispersed to multiple points in catchments. At the same time, we demonstrate a pathway to enable community volunteers to adopt the technology.
Example of cloud-based output from a Mayfly station at the Ōkaro stream.