scholarly journals DESIGN OF AN OVERTOPPING BREAKWATER

1980 ◽  
Vol 1 (17) ◽  
pp. 116
Author(s):  
P.D. Treloar ◽  
B. Nagle

The Maritime Services Board of New South Wales, Australia, is constructing a major new port facility on the northern foreshores of Botany Bay. A principal part of this project has been the construction of a large armoured revetment from the northern shores. The entrance to Botany Bay faces southeast and it is from this direction that a large proportion of offshore wave energy arrives. Some of the wave energy which is directed onto the Bumborah Point revetment is reflected towards Yarra Bay on the northern shores of Botany Bay. Yarra Bay is largely undeveloped, but a sailing club has stood for many years on the beach at the southern end. As a consequence of this reflected wave energy being directed towards Yarra Bay, its wave climate has been changed considerably so that during the storms of May-June, 1974, Foster (6), damage was suffered by the club-house. Additionally the more severe wave climate and consequent steeper beach have made it much more difficult to launch sailing boats. The Maritime Services Board is charged with the responsibility to carry out remedial works where damage is caused by the port development. Figure 1 shows the revetment and sailing club site. To assist in coastal engineering design aspects of the port development, a large fixed bed wave model of Botany Bay has been built to an undistorted scale of 1:120. This model, some aspects of which have been described by Lawson (4), has pneumatic wave generators which enable offshore wave directions between east-north-east and south to be generated with prototype periods in the range of 5 to 16 seconds. A pneumatic tide generator enables a sinusoidal tide to be generated.

1996 ◽  
Vol 118 (4) ◽  
pp. 307-309 ◽  
Author(s):  
M. T. Pontes ◽  
G. A. Athanassoulis ◽  
S. Barstow ◽  
L. Cavaleri ◽  
B. Holmes ◽  
...  

An atlas of the European offshore wave energy resource, being developed within the scope of a European R&D program, includes the characterization of the offshore resource for the Atlantic and Mediterranean coasts of Europe in addition to providing wave-energy and wave-climate statistics that are of interest to other users of the ocean. The wave data used for compiling the Atlas come from the numerical wind-wave model WAM, implemented in the routine operation of the European Centre for Medium Range Weather Forecasts (ECMWF), in addition to directional wave measurements from the Norwegian offshore waters.


1994 ◽  
Vol 17 (1) ◽  
pp. 19
Author(s):  
J. Barker ◽  
D. Lunney ◽  
T. Bubela

Mammal surveys were carried out on the Carrai Plateau and Richmond Range in north-east New South Wales between March 1988 and November 1989. The emphasis was placed on rainforest mammals, following the recognition by Adam ( 1987) that the species lists of mammals in the state's rainforests were incomplete and that more research was needed. The mammals were surveyed primarily by analysis of prey remains in Dog and Fox scats, collected from roads throughout the forests, and from bat trapping. The bat fauna at both the Carrai Plateau and Richmond Range is rich (1 0 species and nine species respectively, including the rare Golden-tipped Bat, Kerivoula papuensis, in the Richmond Range). Scat analysis revealed the presence of 24 native species on the Carrai Plateau, and on the Richmond Range there were 17 species, including high numbers of two pademelon species. Feral prey species are almost completely absent, although the Fox is an established predator in both areas. A sharp division was identified between the mammal faunas of closed and open forests. Differences were found also between the mammal fauna composition of the two rainforest sites, and with those of nearby eucalypt forests. The mammal fauna of New South Wales rainforests is distinct from open forests and future mammal surveys are needed to ensure an adequate level of knowledge to identify and conserve these areas.


1989 ◽  
Vol 11 (2) ◽  
pp. 61 ◽  
Author(s):  
PJS Fleming ◽  
TJ Korn

A monthly survey involving officers from eastern New South Wales Pastures Protection Boards was conducted over four years from 1982 to 1985. Information was collected on the number and type of livestock attacked within each board district, sightings of wild dogs, the number of wild dogs kiied, the method by which they were kiied and the locations at which the observations occurred. A total of 25,644 livestock animals were reported killed or wounded from four regions; the North-East Coastal Region, the North-East Tablelands Region, the Central-East Region and South-East Region. Sheep were the most commonly attacked domestic animals followed by cattle and goats. Regional differences were apparent in the type of livestock killed and seasonal patterns of predation were evident. We recommend that annual control programmes be brought forward from June/July to late April in order to precede predation peaks.


Author(s):  
Sarah Gallagher ◽  
Roxana Tiron ◽  
Frederic Dias

The western coast of Ireland possesses one of the highest wave energy resources in the world and consequently is a promising location for the future deployment of Wave Energy Converters (WECs). Most wave climate studies for this region have focused primarily on the offshore area since it enjoys higher energy densities. However, recent studies have shown that nearshore locations offer a similar potential for the exploitation of wave energy as offshore sites [13]. Furthermore, the proximity of WEC devices to the shore will likely reduce losses in power transport, and facilitate access for maintenance activities. In this context, we analyse the wave climate over a ten year period for several nearshore sites off the Irish West Coast. The wave climate is estimated using a spectral wave model, WaveWatch III, forced with wind and spectral wave data from the ECMWF (European Centre for Medium Range Weather Forecast) operational archive. The wave model is validated with wave buoy data from intermediate to shallow depths (< 60 m). Our focus is on two aspects of the wave climate resource assessment. Firstly, we characterise the directionality of the wave energy resource (mean direction, directional spread) which affects the site selection, design and performance of nearshore WECs. Secondly, we discuss the climate data from the perspective of accessibility for maintenance. When selecting sites for the deployment of WECs, a balance needs to be found between two opposing criteria: the existence of sufficiently long, continuous time intervals of calm sea states (weather windows) which are necessary for maintenance activities to take place, and a high, consistent level of wave energy density, essential for economically viable wave energy extraction.


2003 ◽  
Vol 30 (2) ◽  
pp. 111 ◽  
Author(s):  
Gerhard Körtner ◽  
Shaan Gresser ◽  
Bob Harden

In Australia, baiting with 1080 (sodium fluoroacetate) is widely used to reduce predation of native wildlife by the red fox. However, such control programs may place some native carnivores at risk, particularly the spotted-tailed quoll in eastern Australia. We measured the mortality in a total of 57 quolls fitted with mortality radio-transmitters during four experimental fox baitings with Foxoff® 1080 baits containing Rhodamine B in north-east New South Wales. In all experiments quolls visited bait stations regularly and removed a total of 20 baits. All but one of these baits was found in the vicinity of the bait station, indicating that quolls did not ingest baits. This was confirmed by the absence of Rhodamine B in the vibrissae of all quolls retrapped after baiting. The only quoll that may have died from a bait had eaten a cached bait some six weeks after baiting concluded. Thus, baiting did not threaten any of the quoll populations sampled. Therefore it appears that most restrictions imposed to protect spotted-tailed quolls during fox baiting are unnecessary as long as this bait type is used.


2004 ◽  
Vol 18 (3) ◽  
pp. 291 ◽  
Author(s):  
Kerrie A. Davies ◽  
Robin M. Giblin-Davis

Nematodes of the genus Fergusobia Currie (Tylenchida : Neotylenchidae) and flies of the genus Fergusonina Malloch (Diptera : Fergusoninidae) together form the only known mutualistic association between insects and nematodes that induces galls in young meristematic tissues in Myrtaceae. Six new species of Fergusobia are described (F. quinquenerviae, sp. nov., F. cajuputiae, sp. nov., F. dealbatae, sp. nov., F. leucadendrae, sp. nov., F.�nervosae, sp. nov., and F. viridiflorae, sp. nov.) and partial descriptions are presented for a further two species. Together, these taxa form a putative monophyletic group, apparently restricted to species of Melaleuca in the broad-leaved M. leucadendra-complex, from coastal Queensland and north-east New South Wales, Australia. Each species of nematode has a mutualistic association with a particular species of Fergusonina fly and (with one exception) each association is apparently restricted to one particular species of Melaleuca.


2007 ◽  
Vol 34 (6) ◽  
pp. 484 ◽  
Author(s):  
Ross L. Goldingay ◽  
Matthew J. Grimson ◽  
Geoffrey C. Smith

Although nest boxes have considerable application in the research and management of hollow-using arboreal marsupials, few studies have assessed whether species show a preference for particular nest box designs. This study aimed to determine whether the feathertail glider (Acrobates pygmaeus) showed a preference when offered four different designs, each of which had been used in earlier studies. We established one of each design in 45 plots across five locations, spanning north-east New South Wales and south-east Queensland. Feathertail gliders used 34 nest boxes at four locations but avoided a medium-sized rear-entry box with a 45-mm-diameter entrance. No clear preference was shown for three designs with narrow (≤25 mm) entrances. Feathertail gliders used 15 small rear-entry boxes, 10 large slit-entrance boxes and 9 wedge-shaped bat boxes. A slight preference was shown by breeding groups to occur in the non-wedge boxes compared with the wedge boxes. Squirrel gliders (Petaurus norfolcensis) used 51% of medium rear-entry boxes at four locations. This may account for the avoidance of this box design by feathertail gliders at these locations. Breeding and prolonged use of nest boxes by resident feathertail gliders and squirrel gliders at two locations in eucalypt plantations suggest that nest boxes can support local populations of arboreal marsupials where tree hollows are absent or scarce.


1999 ◽  
Vol 99 (4) ◽  
pp. 248-252 ◽  
Author(s):  
R.J. McGrath ◽  
D. Bass

2008 ◽  
Vol 56 (1) ◽  
pp. 13 ◽  
Author(s):  
Georgia L. Beyer ◽  
Ross L. Goldingay ◽  
David J. Sharpe

Effective management of tree-hollow-dependent wildlife requires a sound knowledge of the characteristics of the trees used for shelter or breeding. We used radio-tracking to identify the den trees of squirrel gliders (Petaurus norfolcensis) in south-east Queensland (Qld) and north-east New South Wales (NSW). Squirrel gliders used dead trees as well as 13 species of living tree for dens across the two locations. Dead trees accounted for a large percentage of dens (54% of 48 dens in Qld, and 50% of 18 dens in NSW) despite comprising only 3–10% of the forest (trees >20 cm diameter at breast height (dbh)) at each location. This preference is largely due to dead trees being more likely to contain hollows, accounting for 26–44% of available hollow-bearing trees. Mean den tree size (dbh) was 48.9 ± 2.4 cm in Qld and 62.8 ± 5.6 cm in NSW. Den entrance height averaged 6.8 ± 1.2 m in Qld and 11.9 ± 1.3 m in NSW. Fissures in the trunk and holes in branches were the most common of six hollow types used. At one location branch end hollows were ignored relative to their availability. Den entrances varied in size (2.5–12 cm wide) but most were ≤5 cm in diameter. Entrance size of hollows appears to be the hollow attribute of most importance to squirrel gliders. Monitoring of these den trees over several years revealed the collapse of three dead den trees at each location, which is equivalent to an annual loss of 3% of den trees. Further research is needed to determine whether this will lead to a future shortage of den trees.


Sign in / Sign up

Export Citation Format

Share Document