Shoreface response to sea level change and the evolution of barrier coasts

This thesis investigates shoreface response to sea level change, and the evolution of wave-dominated coastal barrier systems, in response to late-Quaternary and future environmental change. A numerical stratigraphic model (BARSIM) was calibrated using chronostratigraphic evidence from barrier coasts of southeastern Australia, and was used to explore shoreface response and coastal evolution during the last-glacial cycle and Holocene highstand. The modelling supported previous suggestions that Holocene strandplain progradation was primarily sourced from disequilibrium-stress-induced onshore sand supply, due to the erosion of lower-shoreface sand bodies (e.g. coastal barriers that were overstepped during late transgression). Simulated mid- to late-Holocene sea-level fall, within the bounds of existing evidence, was insufficient to supply observed strandplain progradation. Furthermore, external sand supply resulted in progradation well beyond the depth of present-day barrier complexes. Highstand barrier stacking was found to vary with prior transgressive-barrier behaviour: sea level change and substrate physiography controlled barrier rollover and overstepping behaviours, which resulted in alternative stacking relationships. Hypothetical forward simulations were also carried out to assess the sensitivity of shoreface response (i.e. active shoreface extent, depth-dependent shoreface response rates) and coastal evolution to sea level change. For increasing rates of sea level change typical of the late Quaternary and projected sea-level rise (0.05-10 mm/yr), time-invariant active-shoreface behaviour contracted from the lower shoreface toe to the surf zone. Depth-dependent lower-shoreface erosion was most significant for mesoscale coastal evolution (i.e. 102-105 yrs), which is characterised by partial shoreface activity. The findings suggest that depth- and timescale-dependent shoreface response limit the reliability of equilibrium-profile models for mesoscale problems

Shoreface response to sea level change and the evolution of barrier coasts

This thesis investigates shoreface response to sea level change, and the evolution of wave-dominated coastal barrier systems, in response to late-Quaternary and future environmental change. A numerical stratigraphic model (BARSIM) was calibrated using chronostratigraphic evidence from barrier coasts of southeastern Australia, and was used to explore shoreface response and coastal evolution during the last-glacial cycle and Holocene highstand. The modelling supported previous suggestions that Holocene strandplain progradation was primarily sourced from disequilibrium-stress-induced onshore sand supply, due to the erosion of lower-shoreface sand bodies (e.g. coastal barriers that were overstepped during late transgression). Simulated mid- to late-Holocene sea-level fall, within the bounds of existing evidence, was insufficient to supply observed strandplain progradation. Furthermore, external sand supply resulted in progradation well beyond the depth of present-day barrier complexes. Highstand barrier stacking was found to vary with prior transgressive-barrier behaviour: sea level change and substrate physiography controlled barrier rollover and overstepping behaviours, which resulted in alternative stacking relationships. Hypothetical forward simulations were also carried out to assess the sensitivity of shoreface response (i.e. active shoreface extent, depth-dependent shoreface response rates) and coastal evolution to sea level change. For increasing rates of sea level change typical of the late Quaternary and projected sea-level rise (0.05-10 mm/yr), time-invariant active-shoreface behaviour contracted from the lower shoreface toe to the surf zone. Depth-dependent lower-shoreface erosion was most significant for mesoscale coastal evolution (i.e. 102-105 yrs), which is characterised by partial shoreface activity. The findings suggest that depth- and timescale-dependent shoreface response limit the reliability of equilibrium-profile models for mesoscale problems

Science communication is integral to attracting widespread participation in bushfire recovery citizen science

The 2019/20 bushfire season was a catastrophic event affecting large areas of Australia. Due to the devastating impact on biodiversity, the Australian public wanted to contribute towards assessing the impact of this disaster. To address this, three citizen science projects were established to engage citizen scientists in various aspects of environmental recovery. The projects offered different ways of participating, ranging from online, through to community field events, including those requiring specialised localised knowledge. As a result, communication approaches targeting different audiences were required. Here, we detail the communication strategies employed to promote and engage a diverse national and global audience in bushfire recovery projects. We provide metrics and analysis on how and where we promoted projects, including a breakdown of participation numbers for each project. We detail lessons learnt, and how we would improve our communication approach for future disaster recovery events to increase awareness at a community level and more broadly. Despite numerous challenges, including organising public-facing events during a global pandemic, the program serves as an exemplar of how to successfully partner with communities, research teams and government to enable citizen scientists to make meaningful, valuable and timely contributions to research. Ultimately, the program enabled widespread community involvement in bushfire recovery and filled gaps in baseline and post-fire data

IMPACT OF THE COVID-19 PANDEMIC ON ESTIMATING ELECTRICITY DEMAND AND SUPPLY IN LAMPUNG PROVINCE USING A SIMPLE LINEAR REGRESSION AND CORRELATION APPROACH

This research was conducted to predict the effect of COVID-19 to the total of energy produced by the amount of electricity per capita. The amount of energy produced has the property of being an independent variable or can be affected and electricity consumption per capita has the nature of being an independent or influential variable. This research examines the effect of per capita electricity consumption on the total amount of energy produced in the Lampung region. The research was conducted using regression and correlation experiments. Regression research proves that there is no relationship between electricity consumption per capita and the total amount of energy produced. In contrast, in the linear correlation experiment, there is a correlation between electricity consumption per capita and the total amount of energy produced

Mapping the shoreface of coastal sediment compartments to improve shoreline change forecasts in New South Wales, Australia

The potential response of shoreface depositional environments to sea level rise over the present century and beyond remains poorly understood. The shoreface is shaped by wave action across a sedimentary seabed and may aggrade or deflate depending on the balance between time-averaged wave energy and the availability and character of sediment, within the context of the inherited geological control. For embayed and accommodation-dominated coastal settings, where shoreline change is particularly sensitive to cross-shore sediment transport, whether the shoreface is a source or sink for coastal sediment during rising sea level may be a crucial determinant of future shoreline change. While simple equilibrium-based models (e.g. the Bruun Rule) are widely used in coastal risk planning practice to predict shoreline change due to sea level rise, the relevance of fundamental model assumptions to the shoreface depositional setting is often overlooked due to limited knowledge about the geomorphology of the nearshore seabed. We present high-resolution mapping of the shoreface-inner shelf in southeastern Australia from airborne lidar and vessel-based multibeam echosounder surveys, which reveals a more complex seabed than was previously known. The mapping data are used to interpret the extent, depositional character and morphodynamic state of the shoreface, by comparing the observed geomorphology to theoretical predictions from wave-driven sediment transport theory. The benefits of high-resolution seabed mapping for improving shoreline change predictions in practice are explored by comparing idealised shoreline change modelling based on our understanding of shoreface geomorphology and morphodynamics before and after the mapping exercise

Variability of depth-limited waves in coral reef surf zones

Wave breaking and transformation on coral reef flats is an important process protecting tropical coastlines and regulating the energy regimes of coral reefs. However, the high hydraulic roughness, shallow water, and steep bathymetries of coral reefs may confound common surf zone assumptions, such as a depth-limited and saturated surf zone with a constant wave height to water depth ratio (γ). Here, we examine wave transformation across a coral reef flat, during three separate swell events, on both a time-averaged and a wave-by-wave basis. We use the relationship between significant wave height and water depth (γ) to examine the change in surf saturation across the reef flat and compare the measured wave height decay to results of modelled wave energy dissipation in the surf zone. Our results show that γ was not cross-reef constant and varied according to location on the reef flat and local water depth. On average, γ was greatest at the outer reef flat, near the reef crest, and progressively reduced towards the inner reef flat, near the reef lagoon. This was most pronounced in shallow water with large γ values (γ > 0.85) at the outer reef flat and small γ values (γ < 0.1) at the inner reef flat. This indicates that there is an increase in wave energy dissipation in shallow water, most likely due to increased breaker and bed frictional dissipation. The measured wave energy dissipation across the entire reef flat could, on average, be modelled accurately; however, this required location specific calibration of the free parameters, the wave friction factor (f) and γ, and further suggests that there is no value for either parameter that is universally applicable to coral reef flats. Despite model calibration inaccuracies were still observed, primarily at the outer reef flat. These inaccuracies reflected the observed cross-reef variation of γ on the reef flat and potentially the limitations of random wave breaker dissipation models in complex surf zones. Our results have implications for the use of wave energy dissipation models in predicting breaker dissipation and subsequent benthic community change on coral reef flats, and suggest that careful consideration of the free parameters in such models (such as f and γ) is required

Installation of a pilot experimental trench at the Little Forest legacy site

During 2017, a pilot experimental trench was constructed at the Little Forest Legacy Site (LFLS). The objective of installing this trench was to facilitate experimental field-work aimed at further characterising the site, in particular the hydrology of the excavated trenches and of the near-surface layers in which the trenches are located. The test trench is of similar depth to the waste disposal trenches at the legacy site (3 metres) and extends 6 m in length. However, unlike the disposal trenches, the experimental trench contains no waste materials of any kind. Instead, the trench contains a number of sampling points and other instrumentation, and is back filled with river gravel to provide a uniform composition and maintain structural stability. It is intended that the pilot trench will be followed by other trenches with specific experimental objectives. The purposes of this report are to discuss the background, rationale for, and implementation of the facility; to provide a detailed description of the pilot trench; and to compile information and photographs documenting the excavation process. Although some preliminary hydrological data and comparisons with the legacy trenches are presented, the scientific data will be fully discussed and interpreted in future scientific reports

Downscaling Changing Coastlines in a Changing Climate: The Hybrid Approach

Shifts in the frequency of typical meteorological patterns in an ocean basin, over interannual to decadal time scales, cause shifts in the patterns of wave generation. Therefore, ocean basin-scale climate shifts produce shifts in the wave climates affecting the coastlines of the basin. We present a hybrid methodology for downscaling observed (or predicted) climate shifts into local nearshore wave climates and then into the associated coastline responses. A series of statistical analyses translate observed (or predicted) distributions of meteorological states into the deep water wave climate affecting a coastal region and dynamical modeling combined with statistical analyses transform the deep water wave climate into the nearshore wave climate affecting a particular coastline. Finally, dynamical modeling of coastline evolution hindcasts (or predicts) how coastline shapes respond to climate shifts. As a case study, we downscale from meteorological hindcast in the North Atlantic basin since 1870 to the responses of the shape of the coast of the Carolinas, USA. We test the hindcasts using shoreline change rates calculated from historical shorelines, because shifts in coastline shape equate to changes in the alongshore pattern of shoreline change rates from one historical period to another. Although limited by the availability of historical shorelines (and complicated by historical inlet openings), the observations are consistent with the predicted signal of ocean basin-scale climate change. The hybrid downscaling methodology, applied to the output of global climate models, can be used to help forecast future patterns of shoreline change related to future climate change scenarios.This work was partially funded by the “U.S. National Science Foundation, Coupled Natural Human Systems Program.” J. A. A. Antolínez is indebted to the MEC (Ministerio de Educación, Cultura y Deporte, Spain) for the funding provided in the FPU (Formación del Profesorado Universitario) studentship (BOE-A-2013-12235). J. A. A. Antolínez and F. J. Méndez acknowledge the support of the Spanish “Ministerio de Economia y Competitividad” under grant BIA2014-59643-R