Hydrobiology has a long history with mine closure projects from designing closure criteria to assessing rehabilitation success. We have recently been working in some far flung and interesting areas such as Suriname (pictured) where mine pit lakes have become an asset to the community. It helps having a tropical climate, high rainfall and favorable geology, these pit lakes are more like tropical oasis than a post mining landscape. A combination of traditional survey methods and the latest gadgets are being used to assess the current condition of the lakes and provide information on closure risks and future best-use scenarios. Tools including high-resolution side-scan and down-imaging sonar, drone lidar, photogrametry, multi-spectral imagery, phyisico-chemical, biological and ecotoxicological characterisation are providing a comprehensive snapshot of current conditions and informing risk mitigation requirements for closure.
Key to the measurement of success is having a statistically robust baseline dataset. While the collection of multi-annual/seasonal baseline and reference data can be a costly up-front commitment for closure projects, these costs can be minor in relation to the expense of management responses to poorly established closure criteria. An example of this is where we have observed natural seasonal changes in benthic primary producer coverage (e.g. macro-algae or macrophytes) greater than 50% and where the management trigger was a 15% change. Developing a rigorous conceptual model of your closure site, through collection of multiple lines of evidence, is central to the recommendations of the new ANZG (2018) guidelines. Understanding your aquatic ecological system is core business for Hydrobiology.