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Flow and salinity in the Murray river : Study of flow and salt loads in the Murray River of the Murray-Darling Basin

Brink, I.M. van den (2015) Flow and salinity in the Murray river : Study of flow and salt loads in the Murray River of the Murray-Darling Basin.

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Abstract:The Murray-Darling Basin is Australia’s largest river system. It covers 1,059,000 square kilometres (MDBA, sd) and includes a series of interlinked sedimentary aquifers. The Murray River is the main river in this basin. Much of the groundwater underlying the basin contains of significant amounts of salt. The salinity problems are enormous and are affecting the flora, fauna, irrigation and drink water. To reduce the salinity, many regulations are employed, such as salt interception schemes, injection of fresh water, artificial flooding and dams. Salinity management requires an understanding of catchment data and processes in the Murray-Darling Basin (Fitzpatrick et al., 2007). The routing model used to investigate the effect of salinity regulations is MSM-BIGMOD. It calculates the salt loads using salinity and flow data from sources such as tributaries, anabranches, salt interception schemes etc. However, there is a lack of information about three aspects. First, there are unquantified sources which are not taken into account since the river processes are too complex. The model refers to this as ‘unaccounted salt loads’. Second, there is a lack of information about uncertainties in the input flow and salinity data. Third, the uncertainties in the parameters and model structure are unknown since the model has too many parameters for a proper uncertainty analysis. To get a better insight in the uncertainties and river processes, it is important to develop a simplified conceptual model using a top-down approach. The long term objective is to look at the flow and salinity data including uncertainties, to understand the signals and see if the signals support the processes that are included in MSM-BIGMOD. This research focusses on the first two stages: Conceptualising and testing of a flow model for a particular reach of the Murray River based on data analysis and quantification of uncertainty of the input flow and salinity from nearest upstream sites. Before conceptualizing the flow model, a flow and salinity data analysis is needed to obtain a better understanding of river processes. This analysis shows the complexity of the river processes due to tributaries, anabranches, groundwater recharge and discharge and floodplains. The differences between sites are varying from 24% to 79% caused by the river processes and implemented regulations. Second, this research is about identifying and giving advice how to reduce the different uncertainties in the salinity and flow data. The flow data is obtained using a rating curve instead of direct measurements. The salinity data includes several assumptions or ‘rule of thumbs’. To convert the salinity data to salt load, a conversion factor
Item Type:Essay (Bachelor)
Faculty:ET: Engineering Technology
Subject:56 civil engineering
Programme:Civil Engineering BSc (56952)
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