Nick Harvey

Spatial and temporal variability in the Holocene sea-level record of the South Australian coastline

Abstract Studies of past sea levels based on radiocarbon-dated field samples suffer variously from compilation of information from disparate locations and the imprecise nature of the dated indicators. Geographic segregation and systematic elimination of poor samples from time–depth data sets leads to improved interpretation of Holocene sea-level history. An example is presented from Southern Australia, where this is achieved through selection of higher-resolution palaeoenvironmental indicators, separation of transgressive from regressive populations, and geographic regionalisation of data. In Southern Australia, fossil sea-level indicators preserved in prograding coastal plain settings include seagrass, sandflat, mangrove, samphire and chenier ridge organo–sedimentary remains. These provide sea-level time–depth data points with a variety of elevational and dating errors. Preserved organic remains at the transition from Posidonia seagrass to intertidal sandflat environment, and from sandflat to Avicennia mangrove environment provide the most precise local data for tracing sea-level change. Time–depth plots of 233 dated sea-level indicators from South Australia generate a broad sea-level envelope tracing the Southern Australian transgression from 10,000 to ca. 6000 radiocarbon years BP, followed by a more or less consistent level to the present. Finer details of sea-level behaviour are only apparent after systematic selection, separation and regionalisation of the data. The data indicate a very rapid sea-level rise in the early Holocene, at about 16 mm/year, reaching present levels at 6400 years BP. This was followed by regionally variable regression and emergence of the land of 1–3 m, a process that continues to the present. The systematic increase from 1 to 3 m in the elevation of the 6400-year BP highstand with distance away from the shelf margin is consistent with a hydro-isostatic origin for the emergence as predicted by geophysical models.

Distributed process modeling for regional assessment of coastal vulnerability to sea-level rise

Sea-level rise involves increases in the coastal processes of inundation and erosion which are affected by a complex interplay of physical environmental parameters at the coast. Many assessments of coastal vulnerability to sea-level rise have been detailed and localised in extent. There is a need for regional assessment techniques which identify areas vulnerable to sea-level rise. Four physical environmental parameters – elevation, exposure, aspect and slope, are modeled on a regional scale for the Northern Spencer Gulf (NSG) study area using commonly available low-resolution elevation data of 10 m contour interval and GIS-based spatial modeling techniques. For comparison, the same parameters are modeled on a fine-scale for the False Bay area within the NSG using high-resolution elevation data. Physical environmental parameters on the two scales are statistically compared to coastal vulnerability classes as identified by Harvey et al. [1] using the Spearman rank-correlation test and stepwise linear regression. Coastal vulnerability is strongly correlated with elevation and exposure at both scales and this relationship is only slightly stronger for the high resolution False Bay data. The results of this study suggest that regional scale distributed coastal process modeling may be suitable as a “first cut” in assessing coastal vulnerability to sea-level rise in tide-dominated, sedimentary coastal regions. Distributed coastal process modeling provides a suitable basis for the assessment of coastal vulnerability to sea-level rise of sufficient accuracy for on-ground management and priority-setting on a regional scale.

Foraminiferal biofacies eco-succession and Holocene sealevels, Port Pirie, South Australia

Abstract At Port Pirie, on the eastern coast of Northern Spencer Gulf, South Australia, 10 cores taken along a 3 km transect recovered a succession of Holocene marine sediments. Facies representing shallow subtidal Posidonia seagrass and intertidal sandflat, mangrove and back-storm ridge coastal lagoon environments are recognized on the basis of lithological characteristics and their preserved foraminifera. An assemblage dominated by Nubecularia lucifuga , Peneroplis planatus and Discorbis dimidiatus signifies sediments of shallow subtidal Posidonia seagrass meadows. Subtle changes in the numerical distribution of these species upcore are used to infer the change from subtidal to intertidal sandflat facies; Elphidium crispum and Elphidium macelliforme become more numerous across this transition. The mangrove facies is characterized by Trochammina inflata . This species is present significantly in only one seaward core where modern mangrove woodland continues to grow today and no equivalent biofacies are recognized in other cores. The lagoonal sediments preserve a rich assemblage of species of euryhaline foraminifera. Together with those of the mangrove woodland, they exhibit an ecological succession which can be related to decreasing intervals of tidal inundation and increasing salinity. Helenina anderseni , with subordinate Ammonia beccarii , and Elphidium cf. articulatum are the pioneer species in the euryhaline setting, giving way to Trichohyalus tropicus and Miliolinella schauinslandi . Late stages of hypersaline sedimentation are characterized by Triloculina inflata + Triloculina oblonga . In the mangroves, H. anderseni , A. beccarii and Elphidium cf. articulatum are replaced by Trochammina inflata as the dominant species. In turn, as further sediment aggradation leads to ever shorter intervals of tidal inundation at the landward side of the mangrove woodland, Trochammina inflata is overtaken by Ammobaculites barwonensis . Quantitative foraminiferal biofacies analysis confirms and refines the sedimentological interpretation of intertidal sediment facies from macro-observations of the core materials. It provides independent estimates of the elevation of key facies boundaries in cores and confirmation of a general relative fall in sealevel in Northern Spencer Gulf over the past 7000 yr.

Improving Coastal Vulnerability Assessment Methodologies for Integrated Coastal Zone Management: an Approach from South Australia

The global concern about human-induced climatic change and its potential effect on sea-level has dominated the debate on coastal vulnerability, particularly since a common assessment methodology was developed by the Intergovernmental Panel on Climate Change in 1991. There have been numerous attempts to use or adapt this methodology but the focus has remained on sea-level rise as the single most important issue for coastal vulnerability. This paper presents a revised and more holistic coastal vulnerability assessment methodology which incorporates spatial and temporal scales relevant to the predicted impacts of climatic change and current human-induced hazards. Three studies in contrasting coastal environments of South Australia demonstrate that there are significant regional variations in sea-level response, human-induced hazards and local planning issues and that these may present a greater immediate threat than the possibility of sea-level rise.

Evaluation of environmental impact assessment procedures and practice in Bangladesh

Bangladesh is a major developing country that is particularly vulnerable to environmental change. Since independence in 1971, Bangladesh has implemented a number of environmental initiatives, and is prominent in the global push for sustainable development. Environmental impact assessment (EIA) has a key role in achieving this goal. EIA has recently been introduced through the Environment Conservation Act, 1995 and the Environment Conservation Rules, 1997 but there are a number of inadequacies with the current process. This paper critically examines the evolution of EIA in Bangladesh, the institutional structures supporting it, and case studies of EIA in practice. These data are used together with evaluation criteria to discuss the performance of the EIA process in Bangladesh and make a number of recommendations for improvement.

The role of the Australian Coastcare program in community-based coastal management: a case study from South Australia

Community-based coastal management (CBCM) is recognised globally as an integral feature of integrated coastal management. There are numerous and varied examples of CBCM programs ranging from community driven models to government implemented and coordinated ones. Little evaluation has been undertaken on such coastal programs so there is limited information about the performance of local coastal projects. This paper examines Australias National community-based coastal program designed to involve three tiers of government (National, State and Local) in its implementation. Neither a Commonwealth mid-term evaluation nor State audit of Coastcare for South Australia explore the significance of the Program at a State policy level. This paper bridges that gap by exploring how State goals and objectives for coastal management are aligned with those of the Coastcare program in South Australia.

Triggers for Late Twentieth Century Reform of Australian Coastal Management

This paper identifies four triggers that underpinned the late 20th century reform of coastal management in Australia. These have operated across federal, state and local levels of government. The triggers are global environmental change, sustainable development, integrated resource management, and community awareness of management issues and participation in decision making. This reform has been driven by international and national forces. A number of inquiries into coastal management in Australia culminated in the production of a national coastal policy in 1995. This has led to fundamental changes in coastal management and to the recognition of the inevitability of changes in coastal systems. Federal policies and programs are being translated into action at the state and local government levels through a variety of funding mechanisms and programs. These involve capacity building, a memorandum of understanding between all levels of government, an enhanced role for state advisory or co-ordinating bodies, and an increased role for public participation.

The Impact of Exotic Dune Grass Species on Foredune Development in Australia and New Zealand: a case study of Ammophila arenaria and Thinopyrum junceiforme

Abstract Marram grass (Ammophila arenaria) and sea-wheat grass (Thinopyrum junceiforme) have been introduced to Australia and New Zealand. This study examines the morphology of incipient foredunes and established foredunes associated with these species at two sites, Mason Bay in southern New Zealand, and the Younghusband Peninsula in South Australia. Both species invaded the existing foredunes very rapidly. In both cases the antecedent topography comprised relatively sparsely vegetated, irregular foredunes. Invasion resulted in continuous, regular, evenly vegetated foredunes. At Mason Bay a massive foredune has formed since 1958, in conjunction with Ammophila. Thinopyrum has formed an incipient foredune, with a ramp or terrace morphology, along the Younghusband Peninsula, South Australia. In both cases gaps in the former foredune have been closed and the indigenous foredune vegetation has been displaced. Both species may decrease the frequency and severity of blowout development. They are likely to be resilient to aeolian processes of sedimentation compared with dunes formed by indigenous species. Ammophila survives burial, is tolerant of drought and is resistant to erosion associated with storm surge and high waves. Thinopyrum is very tolerant of salinity. These species may adversely affect the long-term development of coastal barriers by inhibiting transgressive dune development.

Holocene Coastal Evolution: Barriers, Beach Ridges, and Tidal Flats of South Australia

Abstract Coastal evolution following the Holocene marine transgression in South Australia is examined under three contrasting coastal environments: the high-energy, microtidal southeast coast, and the Holocene barrier system of the Sir Richard and Younghusband peninsulas; the sandy deposits of the moderate-energy eastern Gulf St Vincent around the metropolitan Adelaide coastline; and the rapidly prograding sediments of the sheltered subtidal to supratidal gulf environments in the low-energy Upper Spencer Gulf. Although only the Upper Spencer Gulf case study provides detailed data on the Holocene sea level change, collectively, the three case studies illustrate differences in coastal evolution following the transgression, linked to factors such as regional variations in wave energy and wind regime, tidal range, and sediment availability.

Geography and Environmental Studies in Australia: Symbiosis for Survival in the 21st Century?

This paper presents the results of a detailed survey into the reasons for the spate of mergers between Geography and Environment Studies that took place in Australian universities from 1989 to 1999. The results, from a 1998 survey, suggest that the development of a symbiotic relationship between the two areas of study is merely a veneer masking a complexity of underlying factors. These include financial reasons, internal university politics, staff changes and mobility, and only in some cases, a genuine academic rationale for a merger. The paper concludes that the superficial appearance of a symbiosis between Geography and Environment Studies generally masks an opportunistic pragmatism which is very site specific in its complexity. The result has been a series of departmental mergers which, although providing a firmer financial footing, raise questions about the academic implications for the development of both study areas as we move into the third millennium.