Severe tropical cyclone (TC)
Storm tide and wave impacts associated with tropical cyclones (TCs) can result in significant loss of life and damage to coastal infrastructure and property. The combination of wind setup with a barometric surge, resulting from low atmospheric pressure, can elevate water levels above the astronomical tide and breach coastal barriers and defences. The presence of breaking waves can further increase the potential for inundation through wave setup and runup, and cause coastal erosion and structural damage. In many cases, storm tide and wave impacts coincide with pluvial and fluvial flooding during TCs, which can further elevate water levels locally and produce complex and damaging hydrodynamic conditions where river systems meet the ocean.
The Australian region has high exposure to TCs, with an average of 12 events
occurring per year with approximately 5 making landfall (between 1961 and
2017, BoM, 2017). They mainly affect the northern coastline from central
Queensland on the eastern coast (South Pacific Ocean) to the northwestern
coast of Western Australia (Indian Ocean), although the extra-tropical
transition of some TCs to tropical lows means impacts can be felt further
south (Haigh et al., 2014). The highest storm tides (100-year return period
levels
The magnitude of TC-induced storm surge is not linearly related to cyclone intensity. Shoreface slope, shoreline geometry, wind obliquity to the coast, radius of maximum winds (RMW), cyclone track and forward-moving speed all contribute to the surge-producing potential. The existence of offshore islands and reefs can further modulate hydrodynamic conditions to the lee of these barriers, either amplifying or dampening water levels (Lipari et al., 2008). In general, surge potential is maximised on open, straight coastlines with shallow shoreface slopes and slow-moving, landfalling cyclones travelling perpendicularly to the coast. In the Southern Hemisphere and on east-facing coasts, the clockwise flow of low-pressure systems means coastal areas on the southern limb of TCs experience the most wind, surge and wave impacts. Conversely, areas to the north often experience a suppression (set-down) of water levels and low wave impacts due to offshore-directed winds.
TC-induced coastal flooding is maximised when storm surge coincides with a high astronomical tide and energetic wind waves. Non-linear harmonics between tide and surge can further elevate total water levels, especially in areas with large tidal ranges, with some research suggesting surge maxima are more likely to occur on the rising or falling tide rather than at slack water because of this dynamical coupling (Horsburgh and Wilson, 2007). Wave breaking further increases water levels at the coast (wave setup) and adds more forward momentum to the water mass (wave runup), meaning coastal foredunes can be breached even when the storm tide elevation is lower than the dune crest.
The TC season in Australia typically runs from November through to April
(austral late summer to early autumn), when sea surface temperatures are warm
enough for cyclogenesis. In Australia, as elsewhere, TC-affected coasts
(
On 28 March 2017, a severe tropical cyclone (
Because of the intense winds (peak gusts over 260 km h
Approximately 15 h after crossing the coast,
Despite the significant and lasting impacts of tropical cyclones on the
coast, there is a lack of observational data to support process knowledge
and constrain coastal hazard modelling of these events in Australia. By
comparison, the impacts of extra-tropical cyclones on coastal systems is
much better understood (e.g. Turner et al., 2016; Strauss et al., 2017). To
address this data gap, this paper collates and analyses observations of
coastal impacts and concurrent hydrodynamic conditions before, during and
directly after severe tropical cyclone
This work represents the only observational analysis of hydrodynamic drivers and concurrent coastal impacts for a severe tropical cyclone in Australia. The data are of value for the calibration and validation of coastal hazard modelling, both in northern Queensland and for other tropical cyclone-affected eastern coasts in the Southern Hemisphere, such as Mozambique, Tanzania and Brazil, where the genesis of these events is similar but coastal observations are lacking. This paper also provides a case study in data sharing and open collaboration across industry, government and academia, something which is currently lacking in a natural hazard risk context in Australia.
Most beaches on the central northern coast of Queensland receive
few or no ocean swell waves and are only exposed to
low and short-period wind waves generated primarily by southeasterly trade
winds. The median long-term significant wave height,
The Whitsunday and Mackay coastline is situated to the lee of the widest
section of the GBR shelf, with over 180 km separating the outer reefs and
the mainland coast between Bowen and Mackay. In this area, water depths do
not exceed 80 m, but the bathymetry is highly variable. The mean spring
range at Hay Point (
The tidal range at Mackay is 7 times greater than the mean annual wave height (at the Mackay buoy, 35 m water depth). For this reason, beaches in this area are tide-dominated to tide-modified (Short, 2000), with a relatively steep high-tide beach and wide, very low-gradient sand and/or tidal mud flats. At low tide, the water line may be several hundred metres seaward of the high-tide beach. Tidal state therefore plays an important role in modulating storm surge impact in this region.
Coastal embayments in northern Queensland are typically east-orientated, grading from a protected southern end dominated by tidal flats and wind-blown beach ridges towards a more exposed northern end oriented perpendicular to the southeasterly trade winds and backed by transgressive sand dunes (Short, 2000). Longshore transport is generally northward, but can change direction in the lee of headlands.
Results from seven coastal sites are presented. These include (from north to
south) Airlie Beach (20.3
Observations of beach morphological change and storm demand are presented at
the main study sites of Wilson Beach, Conway Beach and Midgeton Beach, which
were some of the most severely impacted coastal locations during
Wilson Beach is a small coastal settlement with a 300 m long beach that faces south across the sand flats and channel of the Proserpine River. The shore consists of a steep high tide beach, fronted by 200 m wide sand and mud flats, adjacent to the river channel (Short, 2000). The houses located closest to the shoreline are built on the sand foredune ridge, with as little as 30 m separating the front doors from the beach crest, which has an elevation of around 5 m Australian Height Datum (AHD).
Conway Beach is a small residential settlement located 2 km southeast of Wilson Beach, with a 1.5 km long beach facing southeast across the Proserpine River mouth. The seafront has a low-gradient high-tide beach flattening to 400 to 500 m wide, low sand flats (Short, 2000). The western portion of the beach (in front of the settlement) is backed by a rock revetment with a crest of between 5 and 6 m AHD. The houses located closest to the shoreline sit approximately 50 m behind the revetment. The eastern section of the beach is backed by a vegetated coastal dune and creek system.
Midgeton Beach is a 1.8 km long, southeast-facing, low-gradient, sandy beach. The high-tide beach is fronted by a wide, low-gradient intertidal beach, with sand flats extending up to 1 km off the southern end in front of the Yard Creek mouth, which forms the southern boundary. A smaller, mangrove-fringed creek (Sandfly Creek) forms the northern boundary (Short, 2000). The community is situated along the northern half of the beach. Foreshore houses initially sit approximately 70 m behind the sparsely vegetated low-lying foredune. Moving southward, the land between the houses and foredune becomes increasingly vegetated and to the south of the community the beach is backed by a foreshore reserve fringed with dense vegetation and coconut palms.
Observations of inundation limits are presented for Airlie Beach, Midge Point, Laguna Quays and Seaforth Beach. Observations of interior and structural damage to buildings resulting from storm tide and waves are presented for Wilsons Beach, Conway Beach and Hamilton Island. The locations of all sites are shown in Fig. 1.
Storm tide monitoring in Queensland was initiated in the mid-1970s and comprises a network of 36 gauges, which all now measure water levels every minute, relative to local Lowest Astronomical Tide (LAT). In this study, elevations were converted to AHD, which approximates to mean sea level. All storm tide gauges are fitted with a barometer which records the atmospheric pressure at the gauge in parallel with water level.
Storm tide gauges and wave buoys used in this study (north to south). AHD conversion from local LAT is given if a site is a storm tide gauge, else mooring depth of water is given for wave buoys.
We define “storm tide” in this paper as the astronomical tide plus meteorological surge components (wind setup plus barometric surge), but not wave breaking effects, which are treated separately. The storm tide gauges used in this study are installed sufficiently far outside the wave breaking zone to not include wave setup, under normal circumstances. They are also all installed on pier or wharf locations which are typically sheltered from wave breaking by design. However, under extreme conditions we cannot exclude the possibility that a small component of wave setup may be captured in a time-averaged sense at the gauges. Our knowledge of these locations suggests this would be minimal, and for the remainder of this paper we make the assumption that wave breaking effects are additional to water levels recorded at the gauges.
Observations from four storm tide gauges located within a 150 km radius of
The meteorological storm surge during TC events includes wind setup and an
accompanying barometric component. Under strong, onshore-directed wind
forcing, the water surface is tilted upward with distance downwind, causing
an increase in the water level towards the coast (wind setup) (Kamphuis,
2010). A barometric surge occurs when there is a surface air pressure
difference between the sea and shore. The inverse barometer (IB) effect can
be approximated as
To estimate wind setup, the IB effect (Eq. 1) was subtracted from the residual between the predicted astronomical tide and the observed water level. In reality, the residual may also include errors in the harmonic derivation of the astronomical tide and non-linear tide–surge interactions (Horsburgh and Wilson, 2007). However, the contribution of these components is outside the scope of this study, so the “residual” is taken as synonymous with the meteorological storm surge.
Ocean wave monitoring in Queensland began in the mid-1970s and now comprises
a network of 16 waverider buoys. Observations from one buoy located to the
north of the landfall site, Abbot Point (14 m water depth), and two to the
south, Mackay (34 m) and Hay Point (10 m), were used in this paper
(Table 1, locations Fig. 1). Even during the extreme conditions measured
during
The buoys measure directional wave spectra, from which parametric data are
derived at 30 min intervals. In this study, we refer to the 0.5-hourly
significant wave height,
Example of the CDF mapping approach used to extrapolate an estimate
of
Due to extreme conditions leading up to
To do this, a cumulative distribution function (CDF) mapping approach was
used (Brocca et al., 2011). This method compares the Mackay and Hay Point
CDFs and adjusts the Hay Point CDF to best match the Mackay CDF. The
Mackay-adjusted Hay Point data were then used as a surrogate for the missing
data at Mackay. Figure 2 illustrates this process for extrapolating
Water levels at open-coast sites include the effects of swash, wave-induced setup and runup, in addition to the storm tide. Swash is generally defined as the time-varying location of the intersection between the ocean and the beach. Wave-induced setup is the super-elevation of the still water level due to the presence of waves. Wave runup is the maximum vertical extent of wave uprush on a beach or structure. Most calculations of runup include the effects of swash and wave-induced setup, and are therefore a measure of the maximum elevation of wave influence above the still water level (or in this case, storm tide). It follows, therefore, that the maximum inundation extent – as evidenced by the most landward detritus lines observed in the field – represents the elevation reached by wave runup above the storm tide.
Wave runup was estimated empirically from wave buoy and beach profile
observations, using the equation of Stockdon et al. (2006):
We used
From this, wave conditions at the time of the peak storm tide were shown to
be in intermediate water depths (
This resulted in an
The beach slope used in Eq. (2) is defined over the area of significant swash
activity (Stockdon et al., 2006). However, for applications to
cyclone-induced runup where large waves likely move the swash zone higher up
the beach profile, the upper (high-tide) beach slope (tan
Wave power is a measure of the energy flux potential in a wave of a given
height travelling at a given speed. The maximum power of waves generated
during tropical cyclones is an important statistic for the design of coastal
and offshore structures. Likewise, the cumulative power of waves during a TC
event is an important indicator of beach and dune erosion potential (Splinter
et al., 2014). The deepwater wave power,
From this, the cumulative storm wave power,
Fugro Roames undertook aerial lidar (light detection and ranging) surveys 8
months prior to
Cross-shore beach profiles were taken through the lidar DEMs pre- and
post-
An on-the-fly GNSS system with post-processing was used for the RF/MQU DGPS
surveys. The mean vertical accuracy was
A team from the Cyclone Testing Station at James Cook University collected land-based and geo-tagged photographic evidence of damage caused to buildings in the areas affected by storm tide inundation and waves. These surveys were focussed on Wilson Beach and Hamilton Island as the two locations receiving the most water damage to buildings.
Maximum surge, storm tide and minimum atmospheric pressure recorded
at gauges (north to south) during
Water levels
Maximum storm surge and components (barometric surge, blue, and wind
setup, orange) plotted as a function of distance from
Wave observations during
Figure 3 shows the water level variations and surge residuals at the four gauges before and after landfall (12:40 on 28 March).
Wave conditions observed (north to south) during
Pre-
Using Eq. (1), the IB and wind setup contributions to the total surge were
estimated at each gauge (Table 2). Figure 4 shows these estimates plotted as
a function of distance around
Wave observations during
Wave runup,
At each site, three cross-shore profiles were taken through the
pre-
Maximum limits of inundation during
Coastal erosion, deposition and inferred transport pathways during
Estimates of maximum water levels were made by locating the most landward
line of debris visible in the field. This can be difficult post-cyclone when
the clean-up operation occurs very early after impact. RF/MQU took DGPS
measurements of inundation markers at Seaforth, Laguna Quays and Midge Point,
4 days after
DEM surfaces were created from pre- and post-
Although we cannot be sure all morphological change in Fig. 7 is attributable
to
Erosion volumes (m
Beach erosion volumes for erosion zones referred to in Fig. 7.
Bracketed values show volume range within reported accuracy of lidar (
Cross-shore beach profile change at Midgeton Beach
(
Pre- and post-storm cross-shore transects were taken through the lidar DEMs
at Midgeton, Wilson and Conway beaches to investigate the beach profile
response to
Cross-shore beach profile changes above 2 m AHD. Bracketed values show percentage of eroded volume.
DGPS elevations were also surveyed along the same profile lines approximately
5 months after
The lidar-derived transects were used to calculate erosion and accretion
volumes above 2 m AHD for each profile (Table 6). The DGPS data were not
used to derive cross-sectional area change, because of the high error (
The storm surge to the south of
According to Hardy et al. (2004) and Haigh et al. (2014), the storm tide
level at Laguna Quays equates to a recurrence of approximately 1000 years.
The storm tide during
It is important to note that these estimates are based on synthetic
extensions of
Either side of Repulse Bay, water levels during
South of landfall, wind setup was the biggest contributor to surge
(accounting for 54 % to 85 % of the total surge residual) because wind flow
was onshore-directed. Conversely at Bowen, north of landfall, the inverse
barometric (IB) effect was the largest contributor to surge (85 %). This
was probably because the wind was offshore-directed at this location,
causing a set-down in residual water levels (Fig. 4). By comparison,
McInnes and Hubbert (2003) found wind setup contributed
Prior to
Another reason for the delay of the surge peak may be the role of tide–surge interactions. Analyses of tide gauges in the North Sea suggest that, in shallow water environments, tide–surge interactions can cause a phase shift in the total water level that means the maximum surge residual (which is the sum of the meteorological surge plus phase-shift effects) is more likely to occur on the rising, and sometimes falling, tide, but almost never coincident with high tide (Horsburgh and Wilson, 2007). Tide–surge interactions are important determinants of surge maxima elsewhere in Australia (e.g. Bass Strait, Victoria – McInnes and Hubbert, 2003, and Broome, Western Australia – Haigh et al., 2014), but their role in modulating extreme water levels along the Mackay–Whitsunday coast requires further investigation.
Wave conditions to the south of
On
Inferred and measured wave heights suggest that wave conditions at all buoys
represent a mid-shelf, shoaled but unbroken wave climate. Wave breaking
usually occurs at a height-to-depth ratio of approximately 0.7, meaning that
even the highest
Because of
Maximum limits of coastal inundation were estimated by summing the local
measured storm tide with an empirically derived estimate of wave runup,
At Midgeton and Conway Beach,
At Wilson Beach,
A selection of post-
At Midgeton Beach, field measurements suggest inundation was lower than at other sites, the empirical estimate, and the local storm tide measurement, reaching only 4.3 m AHD (Table 4). This is likely to be because Midgeton town sits at a lower elevation than the fronting dunes. For the water to have reached the locations at which debris lines were measured, it must have first breached the dune crest, which is between 5 and 6 m AHD.
At Laguna Quays, the storm tide displaced pontoons from their moorings and deposited them on adjacent grassland, providing a useful inundation marker, at around 4.6 m AHD (Fig. 9). Laguna Quays Marina is sheltered from most wave effects; therefore, the total water level only includes the storm tide with perhaps some small additional wave motion. For this reason, the field estimates are close to the maximum storm tide level recorded at the gauge (4.4 m AHD).
At Seaforth, maximum water levels were around 5.2 to 5.3 m AHD along the
central frontage, and 3.8 to 4.1 m AHD at the more sheltered northern and
southern ends of the beach. The highest inundation occurred at Hamilton
Island, where the northeast-facing beach experienced water levels up to
5.9 m AHD. Incidentally, Hamilton Island was the location of the highest
recorded wind gust during
The storm tide contributed between 70 % and 98 % of total water
levels at the mainland, open-coast sites (Conway Beach, Wilson Beach, Midge
Point, Seaforth), with a mean of 84 % (Table 4). By comparison, previous
work suggests the storm tide contributes between 65 % and 75 % of the
total inundation of extreme paleo-cyclones along the northern Queensland
coast (Nott et al., 2009; Forsyth et al., 2010). The higher contribution of
storm tide during
Wave effects were responsible for 2 % to 30 % of total water levels, depending on coastal exposure, with a mean of 16 %. The empirical estimate of Stockdon et al. (2006) did reasonably well in replicating the relative contribution of waves to total water levels. If a regional upper beach slope of 0.02–0.03 is used (as per Short, 2006, and measured at Midgeton and Conway beaches), and the mid-shelf wave record is de-shoaled to deepwater values, then wave effects are estimated at approximately 17 % of the total inundation. This appears to capture the mean, regional contribution of waves to total water levels, assuming sites receive incident wave energy and do not deviate far from the regional mean slope.
The contribution of wave effects at the coast to total water levels was also
expressed in percentage terms relative to the deepwater significant wave height,
At Wilson Beach, the lidar surveys suggest
At Conway Beach, a rock revetment protects the township at the western end
of the bay (denoted in red, Fig. 7b), while the eastern end is a natural
system with vegetated dunes and a small creek behind the beach. The
undefended section showed similar behaviour to Wilson Beach during
Overall, the revetment at Conway Beach appears to have prevented significant overtopping. Figure 7b does, however, suggest there was some overwash of material at the western end between profiles CB1 and CB2, which concurs with the empirical estimates in Sect. 5.3 that maximum water levels around CB1 breached the revetment crest (Fig. 6b). In addition, there is an area of large erosion (beach lowering by up to 1.5 m) directly to the east of the termination of the revetment – perhaps an “end-effect” of the rock wall. End-effects occur when erosion is focussed on areas directly down-drift of a coastal defence, when the structure protrudes seaward of the natural beach crest (as it does at Conway Beach).
At Midgeton Beach, erosion was focussed on the central/northern section of
the beach, in front of the township of Midgeton (approximately
12 500 m
There is little evidence of much landward transport (overwash) of sand at
Midgeton. Likewise, the dunes did not experience any notable roll-over as
seen at Wilson Beach (Fig. 8a–c). Instead, the beach responded similarly to
the revetted section at Conway Beach, where eroded sand was transported
seaward. This may be related to the reinforced stability of the coastal
foredunes at Midgeton; a community-led initiative had ensured they were well
vegetated and in most parts underlain by a geotextile mat prior to
Another commonality between Conway and Midgeton beaches was the major erosion
that occurred near tidal creeks. At Conway Beach, storm water transported
seaward down the creek caused large, localised erosion at the mouth
(
Similarly, at Midgeton Beach, significant erosion occurred at the two creek
entrances, with the southern creek eroding an almost identical volume to the
Conway Beach creek (
The storm erosion demand during
The average storm demand at Midgeton Beach was 15.6 m
These volumes are an order of magnitude smaller than those of wave-dominated
coasts (e.g. 150–250 m
Most profiles saw a net loss of sand above 2 m AHD (average 78 % loss, Table 6), suggesting that the eroded volume was accumulated below (seaward of) this level. The exceptions were CB2 and CB3 at Conway Beach, which experienced a net gain above 2 m AHD, because the depositional lobe that accumulated at the toe of the upper beach extended into the surveyed portion of the profiles. This suggests that at all study sites, sand transport was predominately offshore. At Midgeton and Conway beaches, this may have been in part due to the stabilisation of the coastal frontage. Even at Wilson Beach, however, where the coastal foredune was not stabilised, results indicate that most sediment was transported seaward of the high-tide beach (beyond the limits of our data capture), with only a small portion of the eroded volume overwashed landward.
Our results suggest that while overwash and landward transport clearly
occurred during
Beach profile measurements taken 5 months after
This can be attributed to the wave climate of the region. Tropical cyclones
often impact coastal areas that are equilibrated with a low-energy,
tide-dominated regime because of their latitude and small regional wind-wave
climate. This is particularly the case along the northern Queensland coast,
where a significant amount of wave energy is dissipated over the Great
Barrier Reef (Gallop et al., 2014). This is exemplified in the wave buoy
record pre- and post-
The large energy difference that exists between modal and cyclonic wave
conditions in this region means TC erosion impacts have a permanent impact on
the landscape and require a management response to restore beach amenity and
access. In some geomorphic settings natural rebuilding of the frontal dune
will occur over time; however, this may take a much longer period than
between successive cyclones. For example, photographic evidence 12 months on
from
Where natural recovery processes occur, coastal management actions should be designed to encourage and accelerate natural rebuilding of the beach. For example, the shoreline at Midgeton Beach has eroded and recovered many times over recent decades (Zavadil et al., 2017) and the underlying tendency for many beach ridge systems in northern Queensland is progradation. Natural recovery processes become important for coastal management particularly when engaging local communities about erosion management options.
Although
Fast-flowing water associated with in-flowing (landward) and out-flowing
(seaward) storm tide inundation can cause localised scour around a building
and its foundations. In-flow tends to be more uniform across an area, but is
exacerbated by wave action. Post-
Flooding
In areas affected by tidal creeks, the in/out flow pattern was further complicated. At Wilson Beach, the storm tide entered from two directions: the southern (beach) side, where buildings were directly exposed to wave action, and the northern (creek) side, which was responsible for most inundation of the community (Fig. 10a). Wave action on beach-side properties caused damage to external cladding elements and broke windows and doors on some houses. Wave action also caused substantial drag forces on the substructure of buildings with suspended floors. The window and cladding damage shown in Fig. 10d occurred as waves broke against the wall of the house after it had been knocked off its piles. Inundation by storm tide and waves caused further internal damage to fittings, linings, electrical outlets, floor coverings, and building contents (Fig. 10b), and the receding water left a layer of mud on wall linings and floors (Fig. 10c).
At present, building damage curves that relate cyclone intensity to
structural damage treat wind and water damage separately. Field inspections
post-
Aside from the technical findings of this research, this paper provides a
case study of data sharing across industry, government and academia in a
natural hazard risk context. The research was facilitated through an
information-sharing event (the TC
At a high level, the economic value of data sharing is well recognised (e.g. Deloitte, 2014; World Bank, 2014), but in Australia cross-sector data exchange during natural disasters is lacking (Gissing, 2017). Data sharing can lead to direct and (mostly) indirect economic benefits such as efficiency gains, a reduction in competitive bias, better planning and prediction by regulatory agencies, improved price signalling by insurance, and facilitation of research and innovation. However, reluctance to share information, a lack of co-ordination and standardisation and high costs of data collection often restrict data sharing and encourage the continuance of a piece-meal approach.
In Australia, it is estimated that the centralisation of key natural peril data through the development of open data platforms could save the economy over AUD 2 billion over the period to 2050 (Deloitte, 2014). Because of rising coastal population density (both globally and in Australia), coastal extremes are likely to become particularly costly events. We believe a shared information platform is needed for coastal extremes in Australia, to provide a repository of observational coastal data for historical extremes. In this way, all relevant data and metadata are indexed on an event-by-event basis in a single location. This may include information on the meteorology (winds, air pressure), hydrodynamics (waves, water levels), coastal response (erosion, inundation) and structural (water) damage aspects of individual events that have impacted the Australian coast. At present, a large number of organisations collect this type of information (and most is, in principle, publicly available), but it is often siloed within a discipline or sector. The centralisation of these data would simplify access and increase their collective value, as has been demonstrated in this paper.
Tropical cyclone (TC)
The maximum recorded storm tide was 4.4 m AHD, and the maximum recorded
surge was 2.7 m (Laguna Quays). These were the highest levels recorded at
this location (since the gauge was installed in 1994), with previous work
suggesting a storm tide recurrence of approximately 1000 years. These maxima
are likely the result of surge amplification within Repulse Bay, with sites
north and south recording levels over a metre lower. The considerable
variation in water levels over relatively small spatial scales (
Waves, water levels and coastal impacts were considerably larger south of the landfall site, because of the clockwise rotation of low-pressure systems in the Southern Hemisphere, east-facing coast and onshore air flow to the south of the eye. An average coastal water level (storm tide plus waves) for the region Airlie Beach to Mackay was 5.2 m AHD, ranging between 3.8 and 5.9 m AHD depending on exposure. Total inundation varied dramatically close to tidal creeks. At Wilson Beach, flooding was caused by the storm tide entering the creek and inundating the town from behind, in addition to coastal flooding. The largest beach erosion volumes were also found near to tidal creeks at Conway Beach and Midgeton Beach.
Results suggest the storm tide contributed
The large energy difference that exists between modal and cyclonic wave
conditions in this region (and many other TC-affected global coastlines)
means TC erosion impacts are often a permanent feature on the landscape
within planning timeframes and require a management response to restore beach
amenity and access. Surveys undertaken 5 months on from
To our knowledge, this study represents the only observational analysis of hydrodynamic drivers and concurrent coastal impacts for a tropical cyclone in Australia, and the only set of observations of TC storm erosion demand in northern Queensland. The data were collected on a largely ad hoc basis on a limited budget. We advocate for a more formalised collaborative approach to collecting and archiving TC coastal impact data in Australia, as simple as a publicly available, standardised data depository, to help improve our understanding and prediction of TC-related coastal hazards in the future.
The storm tide and wave buoy data used in this study
(except for the Abbot Point wave buoy) are maintained by the Coastal Impacts
Unit, Department of Environment Science (DES), Queensland Government, and are
available at
TM conceived the idea for the paper and prepared the manuscript. TM prepared the manuscript with contributions from all co-authors, in particular DM, who provided significant input on hydrodynamic forcing. Coastal impact surveys were carried out and analysed by TM, JS, SBL, JM, GB and EZ. IDG contributed to the analysis of field observations and coastal process implications.
The authors declare that they have no conflict of interest.
All coastal impact surveys were funded independently by each contributing
organisation. The Cyclone Testing Station investigation was funded by the
Queensland Department of Housing and Public Works, Australian Building Codes
Board, and other CTS sponsors and benefactors. The authors would like to
thank Bureau of Meteorology (BoM) Queensland State Manager Bruce Gunn for
organising the Tropical Cyclone