Changes in government policy and legislation in recent years has led to increased focus on understanding the groundwater dependence of ecosystems potentially impacted by coal and csg activities. This presentation outlines a study conducted at an operational underground coal mine in the NSW Hunter Coalfields that employed adaptive management techniques to characterise the local groundwater regime and provide advice on the likely level of groundwater dependence of vegetation within an approved area of future mining. The study focusses on vegetation and an aquifer associated with an ephemeral creek that discharges from steep headwaters on to a low-gradient alluvial plain overlying coal measures that will be mined in future using longwall methods.
The study was conducted in an iterative, staged approach that involved collaboration between the client, consultants from multiple disciplines and a government agency. The study included an ecological assessment that identified a River Oak vegetation community, localised along the creek, as the only community likely to be groundwater dependant. While previous surface water assessments provided information on the flow regime. The groundwater component involved field investigations to understand the local geology and groundwater conditions. Findings from the fieldwork, and the ecological assessment were used to locally update an existing regional scale numerical groundwater model. The purpose of the modelling was to establish whether evapotranspiration was simulated across the study area, indicating likely interaction between vegetation and groundwater. Predictive scenarios identified changes in groundwater levels due to mining that may adversely impact vegetation interacting with the groundwater system.
Based on these findings and collaboration between the various technical disciplines, the level of reliance of River Oak community on alluvial groundwater was assessed. The study also looked into where uncertainty may remain in understanding groundwater reliance over time, and from this a targeted monitoring program was developed to enable ongoing adaptive management.
This presentation will outline the methodology, findings and key learnings from the process. This includes discussion on the value and challenges with communication between different technical disciplines and stakeholders.