Arafura swamp water resources study
Williams, D.; Chudleigh, I.; Jolly, P.
E-Publications; E-Books; PublicationNT; Report ; 45/2003
Made available via the Publications (Legal Deposit) Act 2004 (NT).
Dept. of Infrastructure, Planning and Environment
Report ; 45/2003
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24 Figure 25: Wet season tide velocities at G8250007 The series of graphs show a distinct seasonality in the influence of flood and ebb tides. In the dry season both the mouth (G8250006) and upstream (G8250007) records show a slight tendency to be flood tide dominant. That means, that the velocities are higher on the incoming tide (i.e. flood tide) than the outgoing tide (i.e. ebb tide). This behavior means that in the dry season sediments will tend to be pumped or moved upstream. In the wet season during flood events the mouth becomes slightly ebb tide dominated while the upstream tides are severely dampened by the floodwaters. This behaviour means that the wet season will be responsible for exporting sediments from the estuary. A series of satellite images spanning 20 years show that the estuary is expanding, with the upper zone cutting toward the swamp. Grazing and changes in vegetation occurring in this zone may have hastened this process. Comparison of a 1980 satellite image to a 2000 image (Figures 27 and 28) indicates that the estuary has extended headward (i.e. towards the swamp) by approximately 4km over 20 years. This figure gives an average rate of extension of 200 metres per year. At this rate tidal waters may reach the pool at Murwangi (G8250003) by 2025. Further work is required to identify management options to control this headward expansion of the tidal channels of the Glyde River. Modelled Velocity -1.000 -0.800 -0.600 -0.400 -0.200 0.000 0.200 0.400 0.600 0.800 1.000 1.200 36800 36805 36810 36815 36820 36825 36830 36835 36840 Time (days) Ve lo ci ty (m /s ) velocity