Groundwater levels are decreasing due to years of overuse and poor management. Australia has invested in spatial enablement of groundwater management programme for efficient water accounting
Groundwater is an important natural resource, underpinning several national goals. In the last few decades, dependency on groundwater has increased rapidly to support food production, drinking water for a growing population and rapid urbanisation. However, groundwater has not been managed in the past and this has resulted in overuse and falling groundwater levels
Establishing a groundwater management regime is the prerequisite for ensuring sustainable supply of groundwater in the future. Such a regime will have to understand the distribution of the resource and the dynamics of recharge and discharge. Mapping aquifers, predicting future patterns of use and the associated groundwater response, and instituting sound management regimes are key actions that need to be undertaken.
In recent years, Australia has invested in spatial enablement of groundwater management programmes for efficient water accounting and decision making. The government and industry have come together to conceptualise and deliver the following projects: National Groundwater Information Systems, National Aquifer Framework and National Atlas of Groundwater Dependent Ecosystems.
This article discusses the constituents and experiences in developing the above three projects. The projects had different timelines but Sinclair Knight Merz (SKM) built interoperability within the data models so that information is exchanged between the projects.
National groundwater info systems
The Groundwater Data Infrastructure (GDI) is designed to store and analyse point sources and spatially enable groundwater data in line with the draft National Policy Guidelines on Database and Information System. The development of the GDI involved consultation with state and federal jurisdictions on the structure of groundwater data across the country, how it can be organised and the functionality required by each jurisdiction with respect to groundwater aquifer layers. The GDI is built to support an open and transparent environment to manage groundwater data.
The variation in storage formats of preliminary data (bore information, well information, drillers log, lithology log and existing stratigraphy) like paper and digital format (text and spread sheet); poor data quality (for eg, positional accuracy (location of borewells vary using due to different projection), attribute accuracy); development of an aquifer framework; the need for a platform to visualise all preliminary data at one instance for interpreting stratigraphy; the need to extract the interpreted stratigraphy (non-spatial data) to create and analyse hydrological surfaces (spatial data) are the key factors in developing an integrated data model.
The design and development of the GDI and the discovery of the input data are divided into following sub-tasks: Data Model Design, Data Model Review, Data Model Documentation, RDBMS Installation and Setup, Data Model Implementation, Database Test and Refine, Source Surface Geology, and Source Terrain Model.
National Aquifer Framework
In a recent aquifer mapping exercise in Australia, it was realised that the first step is to define the aquifers to be mapped. An agreed understanding of the mapping units and their constituent sub-units was critical in creating 3D aquifer layers. In most cases, the units to be mapped were heterogeneous and consisted a number of sub-units lumped together in a mappable unit of similar hydrogeological characteristics.
Logs of bore-holes provided raw lithological information. Interpreted lithological logs provided information on the stratigraphic units intersected. What was needed is a link between the lithological logs, the interpreted stratigraphic logs and the mappable units. An aquifer framework provided this link.
The Australian National Aquifer Framework is a three- tiered system of:
- Geological Units (GU) — the smallest mappable unit consisting of thousands of mapped surface units plus non-outcropping sub-surface units
- Hydrogeological Units (HGU) — a number of geological units lumped into units of similar hydrogeological characteristics
- Hydrogeological Complexes (HGC) — one or more HGUs lumped into units which are logical to map on a regional scale. These are usually regional aquifers or aquitards.
The GDI has a component to develop a consistent vocabulary across the country which is intrinsic to the groundwater management. The GUs, HGUs and HGCs were developed in workshops including groundwater regulators and consultants. In the aquifer mapping exercises, HGUs were assigned to the interpreted bore logs (ie, a number of HGUs assigned down the vertical sequence). The relationship between the HGUs and the HGCs has been used to map the tops and bases of the each of the HGCs by interpolating between boreholes. If more detail is required in local areas, it had the capacity to map the tops of the HGUs.
National Atlas of Groundwater Dependent Ecosystems
Australia’s mining boom has a significant impact on groundwater resources which in turn affect the ecosystems dependent on it. Australia has developed an online atlas of its groundwater dependent ecosystems (GDEs) using GIS and remote sensing techniques. The primary aim of the GDE Atlas was to create a consistent, nation-wide inventory of GDEs which brings all relevant information on to one Web-based location, collating new and existing information on the hydrogeology, ecology and features of GDEs across Australia.
The development of the GDE Atlas involved the collation of existing GDE data in Australia and significant stakeholder engagement across all jurisdictions in Australia. Where there had been no previous work and existing data was not obtainable, an inflow dependency map derived from remote sensing supports further understanding about the ecosystem as it provides seamless continental coverage. The inflow dependency map therefore overcomes the limitations of sporadic coverage of existing vector data sets.
The GDE layers in the Atlas include GDEs identified in previous studies, and potential GDEs derived through new spatial analysis using existing feature layers and products developed from analysis of remotely sensed data. The primary outputs of the Atlas are spatial layers representing:
- GDEs that rely on the sub-surface presence of groundwater (eg. vegetation), which includes both known (previously mapped) and derived (potential) GDEs
- GDEs that rely on the surface expression of groundwater (eg. rivers, wetlands, springs), which includes both known (previously mapped) and derived (potential) GDEs
- Subterranean GDEs (caves and aquifers), which include known (previously mapped) GDEs; these were mapped only where existing mapping of caves was available, and only in Tasmania – as such, more information on subterranean GDEs exists but has not been collated for the GDE Atlas.
The GDE Atlas also contains contextual information that informs an understanding of the possible groundwater use for each potential GDE. This information describes the ecosystem’s landscape setting, climate, geology, hydrology, ecology and hydrogeology.
The design of the GDE Atlas allows updates as more information becomes available through the backend (Spatial Database). Users can interactively interrogate the data through an online portal, however the limitations are the inability to update, modify or revise the data directly through the Web interface.
While the GDE Atlas provides information available to a broad range of end users, the primary users of the Atlas are water planners and environmental managers, and that the Atlas is used in the early stages of planning process to flag the location and characteristics of GDEs. The Atlas enables end users to view the location and extents, and to retrieve information for various types of GDEs: sub-surface GDEs, surface GDEs, subterranean GDEs, and IDEs. Currently, the GDE Atlas allows only viewing and querying of spatial data related to the ecosystems. If introduced, collaborative GIS will allow expert users to modify the GDE features, attributes, add new features and update the Atlas with more accurate or detailed data sets.
Interoperability of groundwater projects
In order to achieve benefit over the investments done on the above programmes, it was important to ensure interoperability between them. Whilst designing the data model of the GDE Atlas, the design consideration was to make the model interoperable with the interim groundwater geofabric product which in turn is interoperable with the National Groundwater Information System which in turn is also interoperable with the National Aquifer Framework. The interoperability among them enables the end users unlock the value of digital data. The products are now considered part of the National Foundation Spatial Data Framework and will be made available to end use for free via a Web portal by the Office of Spatial Policy (Australian Government Agency) in the near future.