Integration of wetland assessment and management into the hydrogeological landscape framework

Abstract

The Hydrogeological Landscape (HGL) Framework provides a landscape characterisation method to discern areas of similar physical, hydrogeological, hydrological, chemical and biological properties, referred to as HGL Units. The underlying principle of the HGL Framework is that water distribution and movement is controlled by climate, landform, geology, regolith, soil and vegetation properties. Through understanding the patterns of variability in the setting and controls of atmospheric, surface and groundwater systems for a given landscape, the developed HGL Units can be used for hazard assessment and natural resource management centred on water availability, quality, sustainability and associated ecological systems. Applications of the HGL Framework have been used to address dryland salinity, urban salinity, soil and land degradation issues across New South Wales, Tasmania and the Australian Capital Territory (ACT). Wetland presence is determined by the water balance of a given landscape area which favours water to be stored on top of the ground, be it permanently or for temporary periods of time. The water sources and losses for a wetland, varying contributions from each and resulting spatial and temporal dynamics, can allow for a wide variety of wetland water balance equations and hydrological types to be determined. Existing wetland frameworks demonstrate it is the hydrogeomorphological or hydrogeological characteristics of the landscape that will determine the variability in water inputs and outputs for a wetland water balance, a principle shared with the HGL Framework. It is therefore logical that HGL Units and Management Areas can be used as planning units for wetland hazard assessment and management. There are 3 parts to this research: the expansion of the HGL Framework method; using the HGL Framework for wetland hazard assessment and; using the HGL Framework for wetland management. The parts of the thesis are addressed through 5 research aims. The first aim of this research is to trial the use of the Self-Organising Maps (SOM) algorithm to assist in the validation of HGL Units. The second aim is to trial the use of landform modelling to delineate Management Areas within HGL Units. The third and fourth aims are to develop both rapid and detailed wetland hazard assessments where indicators and risk matrices are used to rate and prioritise HGL Units, Management Areas and individual wetlands for further investment and undertaking on-ground Management Actions. The fifth aim is to use the concepts developed in this research to construct a Wetland Module within the HGL Framework to enable wetland managers to identify and prioritise Wetland Functions, effectively select Management Strategies and appropriate on-ground Management Actions to improve current or mitigate future identified hazards. That provides a HGL Framework hazard assessment and natural resource management context that has not previously been explored. Application of the HGL Framework developed 74 regional scale HGL Units for the South East Local Land Services region study area and 25 local scale HGL Units for the ACT study area. Inclusion of the SOM algorithm in the HGL Framework methodology complements the existing expert interpretation and field based validation and testing techniques. The SOM analysis is particularly useful in study areas that the HGL team is less familiar with or where it is financially and logistically challenging to undertake comprehensive targeted testing. The landform modelling approach effectively delineated landscape categories across the ACT, with attribution of Management Areas successfully discerning internal HGL Unit complexity. The modelling outputs and Management Area attribution was able to spatially map both simple topographic sequences in the Werriwa Tablelands and more complex sequences in the Australian Alps (with minor modification),therefore providing a very dynamic landscape characterisation technique to integrate into the HGL Framework methodology. The combined use of SOM and landform modelling techniques ensures greater rigor in determination of landscape patterns, thereby creating a more refined HGL Framework landscape characterisation, hazard assessment and natural resource management tool. Because this approach recognises areas in the landscape that have a discrete set of landscape properties, comparisons can be made within a landscape, across a region, and between regions, nationally and internationally. The HGL Units and Management Areas developed in the earlier part of the research were effectively used as planning units for both rapid and detailed wetland assessments. Regional scale SE-LLS HGL Units were used for a rapid hazard assessment for 11799 wetlands across the Southern Tablelands, to identify broad locations with lower risk to investment and therefore higher potential for successful management. The ACT Management Areas were effectively used as planning units to attributie data to 1296 wetlands and undertake a detailed wetland assessment. The Management Areas identified the internal complexity and topographic sequences within the local scale ACT HGL Units, therefore facilitating a refined hazard assessment which would not have been possible previously, and linked the specific landscape setting to each individual wetland. Variables used in the wetland assessments represented indicators of current anthropogenic pressure, future hydrological change in water sources and losses and future ecological change in vascular plant and amphibian communities. The detailed assessment also assessed multiple climate futures (consensus, wetcool extreme and dry-hot extreme scenarios) allowing wetland managers to consider a range of likely futures and possible desired outcomes. The developed HGL Framework Wetland Module is consistent in approach with the Ramsar Convention wetland vulnerability to climate change assessment framework, and further integrates leading Australian and international conceptual literature. It provides a trade-off analysis for wetland managers to allocate and prioritise Wetland Functions, Management Strategies and Management Actions, to improve or mitigate the currently occurring or identified future hazards. An applied example of the Wetland Module is illustrated using the Ginini Flats Wetland Complex case study.

Date of Award	2017
Original language	English
Supervisor	Leah Moore (Supervisor) & Bill Maher (Supervisor)