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Journal Cover   Australian Journal of Water Resources
  [SJR: 0.479]   [H-I: 4]   [7 followers]  Follow
    
   Full-text available via subscription Subscription journal
   ISSN (Print) 1324-1583
   Published by RMIT Publishing Homepage  [407 journals]
  • Volume 19 Issue 1 - Direct rainfall flood modelling: The good, the bad and
           the ugly
    • Abstract: Hall, J
      The direct rainfall method (DRM) for flood modelling involves the application of rainfall to all cells in a 2D model, and runoff is routed within the hydraulic model. Advantages of this approach include the facilitation of cross catchment flows, a high definition of flow behaviour in catchments, and the approach can replace the requirement for hydrological models within the 2D model domain. Complications can occur when applying the DRM which can lead to unrealistic fl ow responses and large model errors. Issues are generally associated with model losses, run-times, grid-scale effects and very shallow flow. The DRM was used to develop a flood model in the Serpentine area on the sandy Swan Coastal Plain in southwest Western Australia (approximately 20 km south of Perth). The project demonstrates the suitability of the DRM for design flood simulations and floodplain mapping. Due to the problems associated with the approach, a series of checks and quality assurance procedures are recommended if DRM flood modelling is undertaken. This paper explores the pros and cons of the DRM through the processes of model construction, a comprehensive model calibration, validation and sensitivity analysis, and a series of checks including mass balances, and comparison to traditional modelling techniques.

      PubDate: Fri, 3 Jul 2015 22:52:11 GMT
       
  • Volume 19 Issue 1 - A numerical investigation of flow over a side weir
           based on the experimental data
    • Abstract: Namaee, MR
      Side weirs are one of the most important and sensitive parts of flood water spreading systems. Their inappropriate or incorrect function can potentially have an adverse effect on the entire system, making it difficult for flood water spreading systems to perform correctly. Hence, it is necessary to study the hydraulic behaviour of the side weirs. One of the applications of side weirs is predicting the accurate flow measurement in irrigation and floodwater spreading systems. In this study, flow over a broad-crested side weir is numerically investigated based on experimental data under sub-critical condition. The numerical model considers flow over a side weir using Reynolds's Average Navier-Stokes (RANS) equations. The standard k-epsilon turbulence is used to account for turbulence modelling and the volume of fluid scheme was also used in the model to find the free surface of flow. The simulation results are validated by experimental data. They provide detailed analysis of flow patterns, longitudinal pressure distributions over the side weir and also outflow discharge. This study shows that existing numerical models using RANS are applicable in the design of side weirs.

      PubDate: Fri, 3 Jul 2015 22:52:11 GMT
       
  • Volume 19 Issue 1 - Building walls around flood problems: The place of
           levees in Australian flood management
    • Abstract: Wenger, C
      Recent Australian floods have resulted in many changes to levee provisions in Queensland, Victoria and New South Wales. It is therefore timely to review levee issues and current state arrangements. This paper investigates the use of levees as an adaptation measure to address climate change. It also looks at the performance and reliability of Australian levees, environmental impacts, and the relationship between levees and the development of flood prone land. Despite recent changes, there continues to be much scope for improving floodplain development planning and the assessment and management of levees. Development controls continue to be inadequate and this will fuel future demand for levee protection, while lack of development controls behind levees is likely to lead to greater consequences when levees fail, a scenario more likely due to loss of climate stationarity. While levees provide incremental adaptation, they do not offer a long-term solution. However, transformational adaptation measures used in many places overseas are poorly supported by Australian funding programs. Long-term adjustments need to be planned and funded and appropriate incentives and decision-making structures need to be put in place.

      PubDate: Fri, 3 Jul 2015 22:52:11 GMT
       
  • Volume 19 Issue 1 - David Herbert Pilgrim AM (1931-2015)
    • PubDate: Fri, 3 Jul 2015 22:52:11 GMT
       
  • Volume 19 Issue 1 - Preface
    • Abstract: Phillips, Brett C
      PubDate: Fri, 3 Jul 2015 22:52:11 GMT
       
  • Volume 19 Issue 1 - Discussion on "Time-varying character of storm
           intensity frequency and duration curves" by AG Yilmaz, H Safaet, F Huang
           and BJC Perera
    • Abstract: French, R; Jones, M
      Readers of Yilmaz et al's (2014) paper would find it rewarding to first read Westra et al's (2010) paper on climatic non-stationarity, which brings together much research and offers guidance on the subject. For instance, they said "robust statistical results are best obtained by examining annual and seasonal rainfall ... [so] research emphasis also has been on trends in daily or longer timescales, rather than the sub-daily storm bursts", thereby leaving a research gap which Yilmaz et al seek to fill according to their words: "As climate changes, the main changes in precipitation will potentially be in the intensity, frequency, and duration of events".

      PubDate: Fri, 3 Jul 2015 22:52:11 GMT
       
  • Volume 19 Issue 1 - Discussion on "Influence of roofing materials and lead
           flashing on rainwater tank contamination by metals" by MI Magyar, AR
           Ladson, C Daiper and VG Mitchell
    • Abstract: Coombes, PJ
      Investigations by the writer established that the quality of rainwater collected from roofs at Figtree Place and nearby houses in Newcastle occasionally exceeded the values from Australian drinking water guidelines for ammonia, pH and lead (Coombes et al, 2000; Coombes, 2002). However, no exceedances of the guidelines were observed for chemical and metal parameters including Lead in the water column of the storages or at hot water taps. This discovery suggested that rainwater quality in storages improves because metal and chemical contaminants settle to the bottom of the tanks where they sorb to a biofi lm that is commonly known as sludge. Samples taken from the sludge revealed accumulation of lead (0.033 mg/L) and iron (0.93 mg/L). This led to the hypothesis that the water treatment processes of flocculation, settlement, sorption and bio-reaction operate in rainwater storages to improve quality of stored rainwater. Rainwater storages are bioreactors with biofilms at the water surface micro layer, on internal walls and at the bottom as sludge. An important insight was that rainwater should not be drawn from the bottom 100 mm of a rainwater tank to maximise the quality of water by avoiding disturbance of the sludge. Field observations and laboratory experiments revealed that a first flush device designed to capture the first 0.25 mm of roof runoff can remove 11% to 94% of dissolved solids and 62% to 97% of suspended solids from the first flush of runoff into a rainwater tank which would limit the infl ow of chemicals and metals to stored rainwater.

      PubDate: Fri, 3 Jul 2015 22:52:11 GMT
       
  • Volume 19 Issue 1 - Development of drought severity-duration-frequency
           curves in Victoria, Australia
    • Abstract: Rahmat, SN; Jayasuriya, N; Bhuiyan, M
      One of the many ways in preparing for drought is to carry out a drought risk assessment by characterisation of the frequency, severity and duration of a drought. Therefore, the current study aimed at the development of severity-duration-frequency (SDF) curves to provide a comprehensive characterisation of the droughts for 10 selected stations in Victoria, Australia. The development of the frequency curves is based on the precipitation deficits which were computed based on the Standardised Precipitation Index (SPI). Instead of using SPI values, the precipitation thresholds were used to compute the severity of the droughts. This would be very helpful in delivering information that can be understood easily by ordinary users and decision-makers. The SDF curves were developed using the partial duration series (PDS) technique. Log Pearson Type III distribution was chosen and fitted well to the precipitation deficits for different durations of drought. Overall, SDF curves were successfully derived for 10 stations in Victoria and can provide useful information for medium/long term planning, such as in planning irrigation supply and developing drought relief policies.

      PubDate: Fri, 3 Jul 2015 22:52:11 GMT
       
  • Volume 19 Issue 1 - Master recession analysis of transmission loss in some
           Australian streams
    • Abstract: Boughton, W
      A new method of constructing a master recession curve from a daily streamflow record is based on averaging recession values in 15 segments of fl ow range. The results from 100 records on the east coast of Australia show substantial variations in baseflow recessions from the simple exponential decay model Qt = Q0kt usually assumed. The difference between the theoretical exponential decay model and the actual baseflow recession is assumed to be due to transmission loss which varied from zero in two streams to a maximum of 0.186 mm/day in the other 98 catchments. The averaging of recession values in segments of fl ow ranges gives a master recession over the whole range of daily flows unlike just baseflow recessions as in previous methods. The new method is coded into a computer program MASTER, which automatically calculates the master recession and the transmission loss. This is much simpler than earlier methods of constructing master recessions. The method of estimating transmission loss relies on identifying a baseflow recession in the master recession and so is not suitable for use on ephemeral streams in arid and semi-arid areas but provides a means of assessing transmission loss in humid zone streams.

      PubDate: Fri, 3 Jul 2015 22:52:11 GMT
       
  • Volume 19 Issue 1 - Change in in-stream salinity from interception of
           saline groundwater discharge into the Lower River Murray, Australia
    • Abstract: Meissner, AP
      Salt accessions are the major water quality issue of the rivers and streams of the Murray-Darling Basin. The saline Murray Group Aquifer, the salinity of which exceeds 20,000 muS/cm, discharges an estimated 200 t/d of salt into the River Murray in South Australia between Lock 3 and Holder, 40 km downstream. Salinity mitigation works were needed to sustain irrigated agriculture and to maintain the quality of domestic, industrial and urban water supplies. Forty nine wells were drilled to the aquifer between Lock 3 and Holder from late 1989 to August 1990. Pumping of saline groundwater commenced in 1990 to lower the groundwater gradient to the river to zero thus preventing saline water discharging into the river. Telfer and Way estimated that pumping from the aquifer lowered salinity in the river stream by 46.3 muS/cm. Regression analysis of data that restricted it to three years prior to full pumping commenced and to 3 years after zero gradient was achieved, with sites as categorical variables, estimated a reduction of 58.4+/-9.4 muS/ cm for flows </= 10,000 ML/d resulting in a reduction in salt load of 277 t/d. Regression modelling methodology can be extended to assessments of similar saline groundwater interception schemes.

      PubDate: Fri, 3 Jul 2015 22:52:11 GMT
       
  • Volume 19 Issue 1 - Instructions to authors submitting to engineers
           Australia technical journals
    • PubDate: Fri, 3 Jul 2015 22:52:11 GMT
       
 
 
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