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Publications
Supervising Scientist Report 157
Eliot I, Saynor M, Eliot M and Finlayson CM
Supervising Scientist, 2000
ISSN 1325-1554
ISBN 0 642 24361 1
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The Environmental Research Institute of the Supervising Scientist (eriss) at Jabiru initiated a program to assess and monitor coastal change in the Alligator Rivers Region of the Northern Territory. It commenced in October 1996 with funding support for 12 months from the Portfolio Marine Group of Environment Australia. The Environmental Research Institute of the Supervising Scientist extended support for the program until February 1998. The program is currently maintained as part of the core wetland research activities of the Institute.
This report presents an overview of progress in the monitoring program from October 1996 to February 1998. Papers presented in the report detail initiation of the monitoring program and establishment of the framework supporting information acquisition and management. They outline progress with projects commenced under the program, audit existing information and describe areas requiring further investigation.
Development of a regional capacity to measure and assess environmental change will provide a contribution to the National Strategy for Ecologically Sustainable Development agreed by the Council of Australian Governments in 1992. The capacity to measure and assess variation in biophysical processes and land uses has been recognised as a significant component of this strategy. Further, such information can contribute to State of the Environment (State of the Environment Advisory Council 1996) and Marine Environment Report (Zann 1995).
The Alligator Rivers Region in the wet-dry tropics of northern Australia was selected by Environment Australia and collaborating agencies as a key study area for the monitoring of natural and human-induced coastal change. The Region contains the floodplain wetlands of Kakadu National Park, of internationally acclaimed natural and cultural heritage value, several major rivers, and large areas of coastal plain draining into van Diemen Gulf. Its wetlands are already undergoing significant ecological change and, by nature of their elevation and hydrology, are particularly vulnerable to the impacts of climate and other changes, both natural and human-induced (Bayliss et al 1997, Eliot et al 1999, Finlayson et al 1997).
Areas of specific interest in the Alligator Rivers Region include the lowland reaches of inundated floodplains, low-lying seasonally inundated floodplains, deltaic estuarine floodplains and coastal plains described by East (1996). Together, these four geomorphologic units broadly define the coastal zone of the Region. It is a zone of marked interaction between fluvial and marine processes. Tides and other fluctuations in sea level, such as storm surge and those associated with short-term variation in climate, interact with fluvial processes. They give rise to the complex patterns of tidal creeks and salt flats that characterise much of the coastal zone.
The major part of the Alligator Rivers Region, of which Kakadu forms a significant part, is drained by the South Alligator and East Alligator Rivers with the smaller West Alligator and Wildman Rivers draining the north-western portion of the Region. The rivers are fed by a network of ephemeral creeks and drain into van Diemen Gulf, in the north. The combined catchment area of the four major rivers is approximately 28 000 km2, about 8000 km2 greater than the size of Kakadu National Park (Finlayson & von Oertzen 1996a).
The broad coastal plains of the Alligator Rivers Region lie in a narrow band of elevation, 3-4 metres above Australian Height Datum. On the South Alligator River they fall approximately 50 cm in over 70 km. As a result, small fluctuations in river discharge and sea level associated with variation in climate are likely to have far reaching effects on riverine processes, particularly on the tidal hydrology of the streams and the distribution of vegetation on the floodplains. This has been demonstrated through detailed research into the evolution of the floodplains and through systematic accounts of major ecological changes that are currently taking place in the wetlands of the Region (Woodroffe et al 1986, Finlayson & Woodroffe 1996, Bayliss et al 1997, Finlayson et al 1997). The extreme sensitivity of the Region to fluctuations in climate and sea level, such as seasonal variation in weather and those related to El Nino - Southern Oscillation (ENSO) events increases the viability and significance of the monitoring program.
The floodplain wetlands of Kakadu National Park have a high conservation value and cannot be managed in isolation from the remainder of the Alligator Rivers Region or, indeed, lands bordering on van Diemen Gulf (Finlayson et al 1998b). The wetlands are already undergoing major ecological changes and can be expected to change even further, especially given predicted climate change and rise in sea level (Finlayson & Woodroffe 1996, Bayliss et al 1997, Finlayson et al 1997). The ecological character of the Region is partly described, but information upon which changes in character of the valued wetland habitats can be identified are cursory.
Research proposed in the monitoring program includes several large-scale studies monitoring atmospheric and hydrodynamic processes in van Diemen Gulf and the rivers, as well as mapping and monitoring projects specific to environmental change in the wetlands of the Region (Eliot et al 1999). In conjunction with the field-monitoring program, information management will be addressed, and a Geographic Information System structure established for effective data collation, analysis and management across the Region. Participation of other agencies in the program is central to improving data and information management, and will bring wide-ranging expertise to this multidisciplinary initiative.
Monitoring will address processes that influence the stability and rate of change of the floodplain environments (eg Finlayson et al 1997), in particular the switching between saline and freshwater systems with seasonal change from wet to dry conditions (Eliot et al 1999). In addition to studies of large-scale forcing conditions, a suite of local processes will be examined. These include:
· destabilisation of levees vegetated by mangroves;
· headward expansion of tidal creeks;
· basin salinisation; and
· sediment accumulation on the coastal plains.
Existing data sources will be identified and recorded. Data management protocols will be examined and lead to the development of standardised procedures for establishing a metadatabase and a spatial bibliography (Finlayson 1997).
This strategy will enhance previous and current work on coastal monitoring by Commonwealth and other agencies throughout Australia. It will assist in translating international agreements and governmental policy into management action at a local level. Detailed knowledge of biophysical processes in wetlands and the coastal environment are lacking. This lack hinders effective planning and management in these areas (Storrs & Finlayson 1997, Finlayson et al 1998a,b). As coastal wetlands are vital to Australia's natural, cultural, social and economic systems and there is increasing awareness of the need for their ecologically sustainable development (Williams 1998), this proposal is timely.
Change in physical, cultural, social and economic systems is continuous. Therefore, a key factor to be considered is whether environmental change or the rate of change can be perceived as having adverse effects on natural and human systems. On one hand, a heightened perception of change can lead to increased activity to identify, record and implement measures to deal with the changes. On the other hand, a diminished perception of change can result in relaxing measures used in the past to address the negative effects of change. These perceptions have implications that manifest in effects on the natural, cultural, social and economic systems and responses by governments to them.
Governmental responses to such environmental change have been translated into action at a state, territory and local government level through the Australian Intergovernmental Agreement on the Environment (Commonwealth of Australia 1992). More specifically, coastal and marine management problems have been identified by DEST (1995), the Australian Resource Assessment Commission (1993) and Zann (1995). To a varied extent, the implications of environmental change are recognised by all spheres of government through environmental management policies, such as the Commonwealth Coastal Policy (DEST 1995). However, translation of the policies into management action is not always complete, with commitment to the acquisition of a detailed knowledge of biophysical processes and responses to them, as a basis for planning and management at a local level, still required.
Maintenance of the coastal monitoring program at the Environmental Research Institute of the Supervising Scientistwill enable identification of potential changes pertinent to the Alligator Rivers Region and the wet-dry tropics in general, and refinement of methods used to assess the vulnerability of coastal areas to such change. Summary scenarios will then be developed and the potential dimensions, significance and implications of changes will be highlighted to assist land managers in Kakadu National Park and the wider Region to formulate appropriate management strategies.
Major uses and values of the Region are conservation, tourism and recreation, use by Aboriginal people, uranium mining and research activity (Finlayson & von Oertzen 1986b, Bayliss et al 1997). The coastal wetlands constitute the greater part of the coastal zone. Changes to the physical and biological conditions are likely to have cultural, social and economic ramifications. Ultimately, any changes in the environmental conditions will affect the way in which the natural resources of the Region are managed (Finlayson et al 1997, 1998a).
Kakadu National Park is the most important natural, cultural, recreational and tourist resource in the Alligator Rivers Region. The importance of its natural and cultural heritage values are recognised internationally, and it is listed as a UNESCO World Heritage Area. The Aboriginal people of the area, the Bininj, largely own the Park. It is leased by the Commonwealth of Australia and managed by Parks Australia North, an agency of Environment Australia (Kakadu Board of Management and Parks Australia 1998).
Uranium is mined within the catchment of Magela Creek, a tributary of the East Alligator River. The mining leases and nearby townsite of Jabiru have been excised from the Park (Finlayson & von Oertzen 1986b). Mining operations and provision of residential and urban services at Jabiru, together with recreational and tourist activities have direct and indirect effects on the environmental values of the Park. However, management of mining, urban and tourist activities is intended to minimise any adverse impacts. This has been pursued through comprehensive environmental research and monitoring programs at the Ranger uranium mine site at Jabiru East and on the floodplains of Magela Creek (Johnston 1991, Finlayson 1993, Humphrey & Dostine 1994, Humphrey et al 1990, 1995).
The Environmental Research Institute of the Supervising Scientist independently, and in collaboration with other agencies, undertakes and promotes research relevant to the environmental effects of mining operations in the Region and minimisation of these effects after decommissioning and rehabilitation. The coastal component of the research has focussed on downstream effects of mining, however, much of the information is applicable as a baseline to assess the effects of climatic and other changes on the catchment environment. It also provides a sound basis for comparison with other parts of the Region. This information base has underpinned the development of a wetland research program with a strong emphasis on monitoring change and involving local community groups (Spiers & Finlayson 1998).
Extensive scientific research has been undertaken in the Alligator Rivers Region. It commenced in the early 1970s with the Alligator Rivers Region Environmental Fact Finding Study (ARREFFS) which, at the time, was the most comprehensive study of its type ever undertaken in Australia (Christian & Aldrick 1977). Results of the ARREFFS and the subsequent Ranger Uranium Environmental Inquiry were used in the environmental assessment of the impact of mining and milling uranium ore (Ranger Uranium Mines Pty Ltd 1974a,b & 1975) in the Region (Fox et al 1977). Research has continued with an emphasis on the management of Kakadu National Park. As a consequence of the history of research, information available for the wider region matches the breadth and detail of that for many coastal areas in Australia, which carry a much larger population.
Literature sources, including published scientific papers, reports and unpublished reports were collated by Bayliss et al (1997) as part of an assessment of the vulnerability of the Alligator Rivers Region to the possible effects of predicted climate change and rise in sea level. The literature was used to:
· Identify climatic and other changes that are pertinent to the assessment of the vulnerability of coastal and wetland areas of the Alligator Rivers Region (ARR) and to Kakadu National Park (KNP).
· Review the methods and approaches used to assess the vulnerability of coastal areas to natural and human induced change.
· Develop summary scenarios for climate and other changes that can be related to the Alligator Rivers Region and Kakadu National Park in general, and to the Magela floodplain in particular.
· Provide background descriptive information on the areas that could be affected by change by way of natural, cultural, social and economic resources of the areas.
· Review the specific and cumulative effects of the change processes identified in the areas.
· Assist in the development of an assessment framework and highlight the dimensions, possible significance and the potential implications of the changes.
· Gain an understanding of types of responses to change that would be relevant to the Alligator Rivers Region and Kakadu National Park.
· Provide a benchmark for determining the actions most suited to implementation across the Alligator Rivers Region and Kakadu National Park.
Additional sources of information relating to the Alligator Rivers Region that are considered relevant to this strategy include:
· Alligator Rivers Region Geographic Information System (ARRGIS) (Riley 1992, Devonport & Riley 1993);
· Environmental Resource Mapping System (ERMS) for Kakadu National Park (Ryan et al 1995);
· Satellite imagery for the Alligator Rivers Region and Kakadu National Park highlighting specific environmental characteristics (Hausknecht & Milne 1998, Milne et al 2000) (see Paper 2);
· Aerial photography for the Region, Kakadu National Park and specific localities such as the mine lease areas, Point Farewell and areas of salt water intrusion (Cobb et al 2000, Paper 8 in this volume);
· Thematic maps of the natural resources of the area (eg Schodde et al 1987);
· Meteorological, hydrological and tidal prediction data (see Papers 3, 4 & 5);
· Quantitative results of the monitoring programs (Finlayson 1988, Johnston 1991, Humphrey & Dostine 1994, Humphrey et al 1990, 1995, Bishop et al 1995); and
· Oral and written history of land use and environmental change (see Paper 6).
Although a range of information is available, there has been considerable information loss - including missing copies of scarce reports, data from field investigations and memoranda outlining results of research. As a result, information management is a significant issue.
Critical issues confronting the coastal zone have been identified many times. The Commonwealth Government has recognised them in numerous inquiries and discussion papers. The most recent of these are the report of the House of Representatives Standing Committee on Environment Recreation and the Arts (1991), the final report of the Resource Assessment Commission Coastal Zone Inquiry (Australian Resource Assessment Commission Coastal 1993) and the Commonwealth Coastal Policy prepared by the Department of Environment, Sport and Territories (1995). The last of these also provides the policy context for this proposal.
The Commonwealth has responsibilities that significantly affect management of the coastal zone. It is necessary to ensure that these responsibilities are carried out effectively. The Commonwealth Coastal Policy is the basis for putting the Commonwealth's house in order. Thus, the Commonwealth Coastal Policy provides a framework within which the activities of Federal Government departments and agencies that may have an impact on the coastal zone will be developed and implemented. Management of the coastal wetlands of Kakadu National Park is a Commonwealth activity that falls within the ambit of the Commonwealth Coastal Policy.
Selection of the Alligator Rivers Region for the monitoring and management of coastal change arose from recognition of the significance of Kakadu National Park. It is a major regional resource in the wet-dry tropics. Other contributory factors include the apparent susceptibility of the Region to change, management of the Park by Aboriginal people and the Commonwealth Government for the purposes of conservation and tourism, and the scope offered to integrate a range of coastal initiatives being implemented within a single Commonwealth Government portfolio.
Despite its susceptibility to change, the Alligator Rivers Region is relatively untouched in comparison with other areas. Therefore its management can serve as a benchmark for management of other parts of the wet-dry tropics.
Information and experience gained from the survey and assessment process developed in the Alligator Rivers Region should assist other government agencies and Aboriginal organisations to appreciate and manage problems underlying environmental variability in remote areas. For example, outcomes of the assessment will have ramification for the Kimberley coast, Arnhem Land and parts of the Northern Territory and Queensland bordering on the Gulf of Carpentaria, given the biogeographic similarities and the absence of an equivalent information resource and research infrastructure in these areas (Finlayson 1995, Finlayson et al 1998b).
Wetlands in the wet-dry tropics encompass seasonally inundated floodplains and swamps, coastal salt flats, mangrove swamps and estuaries. The conservation value of these wetlands is well recognised, as are the physical and biological linkages between them (Storrs & Finlayson 1997). However, the information base is uneven and, in many instances, poor. A broad scale inventory base for these valuable ecosystems does not exist.
The objectives of the coastal monitoring program are to:
· Coordinate and document change in the Alligator Rivers Region, including Kakadu National Park and van Diemen Gulf, incorporating the coastal wetlands, shores and nearshore waters.
· Provide information and advice to assist strategic planning, preparation of coast and catchment plans, and implementation of specific management programs.
· Enhance information management, including ownership of spatial environmental information.
· Establish a baseline and reference station to provide input to the National Coastal Monitoring Program under the Commonwealth Coastal Policy.
· Support the administration and operation of long-term monitoring programs that focus specifically on climate change implications for the management of the tailings dam and mine tailings and overburden stockpiles in the catchment of the Magela Creek.
· Audit the effectiveness of planning and management activities in Kakadu National Park and van Diemen Gulf.
The coastal monitoring program will enable the principal scientific organisation of the Region, the Environmental Research Institute of the Supervising Scientist, to provide primary baseline information, particularly time series describing environmental change, for management of the floodplains and coastal zone of Kakadu National Park. In turn, the information will enable the Commonwealth managing authority, Parks Australia North, and the Traditional Owners to anticipate and respond to change in a manner that does not compromise the environmental and cultural values of the Region.
Anticipated outcomes include:
· Establishment of a coastal monitoring program, responsible for acquisition, analyses and dissemination of time series information describing biophysical change on the floodplains and coast of the wet-dry tropics.
· Development of a predictive capability for identifying potential environmental responses to climate change and sea level fluctuation.
· Establishment of long-term monitoring of key biophysical parameters in the wetlands and adjacent seas as a basis for assessment of environmental change and establishment of appropriate natural resource management strategies.
· Increased community awareness of the nature and scope of temporal variation in the floodplain environments of the wet-dry tropics.
The report opens with statements of intent and a description of the area of interest. This is followed by consideration of data collection and information management tasks that provide a framework for the monitoring activities. We then list details of projects contributing to an understanding of large-scale, regional processes and forcing conditions that underlay much of the environmental change occurring on the coastal plains, and identifying change at a local-scale. Finally we then discuss potential applications and accountability for work completed. The structure and organisation of the report is shown as a flow diagram in figure 1.1.
The report provides a hierarchical approach to the coastal monitoring program in two respects. First, the sequence of papers follows the order in which the monitoring program is evolving. Second, the completeness of papers presented varies with the hierarchical order. The most complete aspects of the monitoring program relate to its organisation. Even after two years collation, baseline information in many areas is incomplete and ongoing, and several planned projects remain to be implemented.
The full report can be ordered from publications_ssd@environment.gov.au
Eliot I, Saynor M, Eliot M and Finlayson CM 2000. Assessment and monitoring of coastal change in the Alligator Rivers Region, northern Australia. Supervising Scientist Report 157, Supervising Scientist, Darwin.
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