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1.
Claire Kain Christopher Gomez Patrick Wassmer Franck Lavigne Deirdre Hart 《New Zealand geographer》2014,70(3):165-178
The 2004 tsunami transformed the coast of Indonesia. This research investigates a sand dune area in Lampuuk, Sumatra, that was scoured by tsunami flow. We assessed geomorphology one‐year post‐event and examine the timescale of vegetation recovery. Ground Penetrating Radar (GPR) evidence shows an eroded succession of thin dipping units, overlain by aeolian layers 0 to 50 cm thick. Incipient dunes were absent, indicating limited dune rebuilding at one‐year post‐tsunami, possibly resulting from channelised airflow and the absence of vegetation. Recolonisation by vegetation was initially limited but progressed rapidly between 2005 and 2011, highlighting the temporal non‐linearity of recovery processes. 相似文献
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Mathematical Geosciences - Equations describing facies proportions and amalgamation ratios are derived for randomly placed objects belonging to two or three foreground facies embedded in a... 相似文献
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Deirdre Dragovich 《The Australian geographer》2015,46(3):411-413
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The Massachusetts Water Resources Authority (MWRA) conducts monitoring to address concerns related to the 2000 diversion of secondarily treated effluent discharge into Massachusetts Bay. Baseline data (1992-2000) showed multiple regions defined by physical and chemical composition. Near the Massachusetts Bay outfall, there is a series of heterogeneous sediments in relatively close proximity to the primary historic source of contaminants (Boston Harbor). Farfield sediments exhibited greater compositional definition from one another, which was attributed to the greater spatial separation of the sampling locations. Factors that influence contaminant variability include local and distributed sources, and are primarily related to gradients in depositional environments. Post-diversion sediment data suggest that 4 years of treated effluent discharge has not increased contaminant concentrations to the bay system. However, abundance of the sewage tracer, Clostridium perfringens, has increased variably in sediments located within 2 km of the outfall, providing a distinct effluent signal near the outfall. 相似文献
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Seafloor pressure records, collected at 11 stations aligned along a single ground track of the Topex/Poseidon and Jason satellites,
are analyzed for their tidal content. With very low background noise levels and approximately 27 months of high-quality records,
tidal constituents can be estimated with unusually high precision. This includes many high-frequency lines up through the
seventh-diurnal band. The station deployment provides a unique opportunity to compare with tides estimated from satellite
altimetry, point by point along the satellite track, in a region of moderately high mesoscale variability. That variability
can significantly corrupt altimeter-based tide estimates, even with 17 years of data. A method to improve the along-track
altimeter estimates by correcting the data for non-tidal variability is found to yield much better agreement with the bottom-pressure
data. The technique should prove useful in certain demanding applications, such as altimetric studies of internal tides. 相似文献
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Sebastian J. Pitman Harry M. Jol James Shulmeister Deirdre E. Hart 《地球表面变化过程与地形》2019,44(8):1610-1617
Beach ridge stratigraphy can provide an important record of both sustained coastal progradation and responses to events such as extreme storms, as well as evidence of earthquake induced sediment pulses. This study is a stratigraphic investigation of the late Holocene mixed sand gravel (MSG) beach ridge plain on the Canterbury coast, New Zealand. The subsurface was imaged along a 370 m shore-normal transect using 100 and 200 MHz ground penetrating radar (GPR) antennae, and cored to sample sediment textures. Results show that, seaward of a back-barrier lagoon, the Pegasus Bay beach ridge plain prograded almost uniformly, under conditions of relatively stable sea level. Nearshore sediment supply appears to have created a sustained sediment surplus, perhaps as a result of post-seismic sediment pulses, resulting in a flat, morphologically featureless beach ridge plain. Evidence of a high magnitude storm provides an exception, with an estimated event return period in excess of 100 years. Evidence from the GPR sequence combined with modern process observations from MSG beaches indicates that a palaeo-storm initially created a washover fan into the back-barrier lagoon, with a large amount of sediment simultaneously moved off the beach face into the nearshore. This erosion event resulted in a topographic depression still evident today. In the subsequent recovery period, sediment was reworked by swash onto the beach as a sequence of berm deposit laminations, creating an elevated beach ridge that also has a modern-day topographic signature. As sediment supply returned to normal, and under conditions of falling sea level, a beach ridge progradation sequence accumulated seaward of the storm feature out to the modern-day beach as a large flat, uniform progradation plain. This study highlights the importance of extreme storm events and earthquake pulses on MSG coastlines in triggering high volume beach ridge formation during the subsequent recovery period. © 2019 John Wiley & Sons, Ltd. 相似文献
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Ocean Science Journal - A minimum 19 year tidal prediction dataset covering nodal (satellite) modulation effects is required to determine the Lowest Astronomical Tide (LAT) and Highest Astronomical... 相似文献
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Sediment movement (slopewash and bio‐transfer), runoff, and organic matter movement (mainly leaf litter, ash and charcoal) were monitored on ten plots for a six‐month period following bushfires in eastern Australia in the 1990s. Plots were installed in areas which had experienced high, moderate and low intensity burns. Although between‐plot variability was high, slopewash and organic matter amounts were greatest on the intensely burnt areas, and progressively less on moderate and low intensity burns. In contrast, most leaf litter input from scorched leaf fall was derived from, and collected in, moderately burnt areas. Bio‐transfer of sediment (direct downslope surface movement produced by faunal activity) occurred mainly by ant mounding, and was more than ten times greater on moderately burnt areas than on plots having high or low intensity burns. Bio‐transfer accounted for approximately 36 per cent of total sediment collected, with this material being recorded least often and in smallest quantities on areas of high intensity burns. Bio‐transfer by ant mounding and animal scratchings contributed loose surface sediment for transport by overland flow, disproportionately increasing total sediment movement to plot aprons in areas of moderate intensity burns. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
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Local sandstone used in nineteenth century buildings in Sydney has been affected by salt weathering and surface crust formation.
This study trialled two approaches, namely washing-and-vacuuming and poulticing, to salt-removal treatment of weathered sandstone
blocks from the Sydney Hospital and Australian Museum. Both treatments removed solutes from the stones in laboratory tests.
ICP/titration of sampled scrapings at depths of 0–2, 2–5 and >50 mm showed substantial between-sample variation, with no significant
difference being recorded in solute levels after treatment (Mann–Whitney U test), except for sulfur and sodium. Sulfur levels increased at the surface (0–2 mm) following washing-and-vacuuming but
not poulticing for the Hospital and Museum samples. Sodium levels increased at the surface (0–2 mm) following poulticing but
not washing-and-vacuuming for the Hospital samples. The presence of surface crusts may have contributed to some of the variation
in desalination responses. 相似文献