Time filter

Source Type

Brisbane, Australia

Brown I.,GHD
The Art and Science of Water - 36th Hydrology and Water Resources Symposium, HWRS 2015 | Year: 2015

Managing stormwater quantity in North Queensland coastal plain areas is a key challenge for local authorities and has come under recent pressure by local communities. Recent extreme events have resulted in significant increases in insurance premiums in flood prone areas, along with generational changes resulting in changes in property uses. Coupled with the future risk of rising sea water levels, local authorities have been reminded to maintain vigilance in developing strategies and policies in a proactive manner. Effective management of stormwater in North Queensland coastal areas however remains a difficult task due to the comparatively high rainfall and resulting runoff, along with ever increasing development pressures and encroachment on waterway areas. Recent studies developed for two central residential suburbs in Cairns identified a significant number of properties were affected by the 1 % annual exceedance probability event or less depending on the location. A number of factors contributed to the issue, including the impact of elevated tailwater levels, the naturally low ground levels, the runoff responsiveness of catchments, and the constriction of conveyance paths resulting from flat terrain, historic frontal dunes, bank stability, and sediment deposition. In addition, many new properties are built as slab on ground, or existing pole homes have been renovated to include living areas on the ground floor which are now being affected. Traditional flood mitigation techniques have been investigated to improve the current situation. These included detention basins, levees, channel widening/dredging and tidegates. However, due to the magnitude of rainfall and the unique conditions encountered in coastal plain areas, traditional techniques did not prove cost effective for the expected level of improvement. As a result, nontraditional methods were investigated. Flooding has historically been caused by low conveyance in waterways. The encroachment of development near these waterways has also limited the scope for waterway widening, so the provision of alternate outlet arrangements was contemplated. Based on the assessments undertaken, it was concluded that increasing the flow capacity of the existing stormwater systems, rather than reducing the runoff quantity, was deemed to be more effective in improving the upstream flood extent. Both gravity systems and pumped systems have been investigated in Cairns and found to be effective in reducing the flood water levels. These techniques have also been assessed and intended to be implemented in other parts of coastal North Queensland with similar stormwater management issues. © 2015, Engineers Australia. All rights reserved. Source

Davis R.W.,Bentley Delivery Center | Hurter P.J.H.,GHD
Nuytsia | Year: 2012

Solanum albostellatum R.W. Davis & P.J.H. Hurter has recently been discovered and is formally described. The new species is morphologically similar to S. oldfieldii F. Muell. and S. esuriale Lindl. Solanum albostellatum inhabits cracking clay environments extending from Millstream Chichester National Park to the Hamersley Range, west of Newman. An amendment to the Flora of Australia key for Solanum to account for S. albostellatum is included, as is a table summarising the similarities and differences between S. albostellatum and the most similar taxa. © Department of Environment and Conservation 2012. Source

Tuladhar R.,James Cook University | Lancini B.J.,GHD
Structural Engineering and Mechanics | Year: 2014

The use of low-ductility welded wire fabric (WWF) as a main tensile reinforcement in concrete slabs compromises the ductility of concrete structures. Lower ductility in concrete structures can lead to brittle and catastrophic failure of the structures. This paper presents the experimental study carried out on eight simply supported one-way slabs to study the structural behavior of concrete slabs reinforced with low-ductility WWF and steel fibers. The different types of steel fibers used were crimped fiber, hooked-end fiber and twincone fiber. The experimental results show that the ductility behavior of the slab specimens with low-ductility reinforcement was significantly improved with the inclusion of 40kg/m3 of twincone fiber. Distribution of cracks was prominent in the slabs with twincone fiber, which also indicates the better distribution of internal forces in these slabs. However, the slab reinforced only with low-ductility reinforcement failed catastrophically with a single minor crack and without appreciable deflection. Copyright © 2014 Techno-Press, Ltd. Source

Seawater and brine salinity in reverse osmosis applications are commonly determined in the desalination industry by the following methods; evaporation, summation of ions or salinityconductivity relationships. Results from these methods are often abbreviated as "TDS" irrespective of whether the measurement is actually referring to "solids" or "salts". Although, these methods should yield the same result, often they do not. Differences in the results are explained in this paper, following a review of the methods. Examples of seawater and brine salinity determined as salinity and TDS are given highlighting the advantages and limitations associated with each method. Summation of ions yielding Total Dissolved Salts (TDSalts) is recommended for discrete sampling to provide a breakdown of constituent ions for process design and monitoring. While the Practical Salinity Scale (PSS-78) used in oceanography is recommended as the method of choice for both continuous and discrete sampling for process and environmental monitoring. PSS-78 allows consistent measurement of seawater and brine salinity on land and at sea. © 2012 Desalination Publications. All rights reserved. Source

Litwinowicz A.,GHD | De Beer M.,South African Council for Scientific and Industrial Research
Road Materials and Pavement Design | Year: 2013

Evaluation of the crushing (or compression) failure and associated surface deformation of lightly cementitious (stabilised) materials used for base/sub-base course in pavements has been well established in the South African pavement design practice since the 1990s. This paper presents a re-evaluation of this earlier work, focusing on expanding the empirically derived crushing performance relationships (i.e. transfer functions or damage laws) for lightly cementitious materials at in situ moisture conditions, i.e. without the adverse effect of additional or artificial water infiltration into the lightly cementitious base, which limited the practical application of the original transfer functions for significant rutting. The re-evaluation was undertaken to determine whether the original crush initiation relationship was reasonable for as-built moisture conditions and also to develop practical advanced crushing damage relationships for various rut depths developing within the base, based on the measured response of the original test sections prior to water ingress. The newly derived crush initiation relationship differs little from the original and either can be used with similar confidence. However, the new 10 mm rut relationship differs significantly from the original relationships (which were derived from the adverse statistical bound of the crush initiation data), the previous relationship should now be abandoned, and the new relationships adopted for well-protected pavements. The newly developed advanced crushing damage relationships for 5, 10, 15 and 20 mm level of deformation ("rut") within the lightly cementitious base layers are proposed for practical application to in situ as-constructed (as built) moisture conditions. © 2013 © 2013 Taylor & Francis. Source

Discover hidden collaborations