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  1. #11
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    It'll be interesting what you find Shaun, there is two large ( but shallow) masses of water in the two lakes, it does funny things. Fishing the stretch of river between the lakes, you can fish a tide at one end then move and fish the same tide at the other end. As chewy said the up stream end of the between the lakes stretch is the reverse of the river mouth, but then again some days it isn't. Simple really!

    I look forward to your findings.
    .

  2. #12
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    Do you imagine that the differences (if any) might be associated with the full/dark moon tidal behaviour and the neaps tidal behaviour at the top end of 1 lake and the bottom end of the other lake? With both different to the standard port.

    Significant differences that exist in 1 place between neaps and full/dark moons also happen in other places.

    Imagination is easy.

    I guess others will look forward to the "findings" as well, eh Didley?

  3. #13
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    Quote Originally Posted by Douglas View Post
    Do you imagine that the differences (if any) might be associated with the full/dark moon tidal behaviour and the neaps tidal behaviour at the top end of 1 lake and the bottom end of the other lake? With both different to the standard port.

    Significant differences that exist in 1 place between neaps and full/dark moons also happen in other places.

    Imagination is easy.

    I guess others will look forward to the "findings" as well, eh Didley?
    have you actually fished of boated on the nossa river upstream of lake Coorooibah Douglas?
    Chewy....
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    Its the quest,not the conquest...

  4. #14
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    I guess that the differences in the joining stream will be related to the amount of water that has to be shifted between the 2 lakes (that varies from tide to tide) and the varying times in which that varying amount of water has to be shifted?

  5. #15
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    Quote Originally Posted by ActiveAngler View Post
    have you actually fished of boated on the nossa river upstream of lake Coorooibah Douglas?
    No and don't have to Paul.

    Issue is movement of water between 2 constricted waterways. You could liken it to two reservoirs connected by a 8 km pipeline.
    Last edited by Douglas; 08-12-2018 at 07:59 PM.

  6. #16
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    Reservoir 1 is Lake Cooriobah and reservoir 2 is Lake Cootharaba connected via a 8 km pipeline and they're trying to balance (allow water from both to find a common level).

    Only problem is there is extra water pumped into the bottom reservoir via the tides at regular intervals. How much water (and consequently the difference in "heads") is determined by the tidal differences between Tewantin and Noosa Hd.

    Then the effect of water movement between Cooroibah and Cootharaba is dependent on the difference in the incoming volume of water via Tewantin. And THAT amount is dependent on the moon phase.

    That's why the tidal differences aren't static.

    The two lakes are differing volumes so one (Cootharaba) will tend to dominate what happens in Cooriobah.

    Think about the VOLUME of incoming water via Tewantin and its effect on the head of water in Cooriobah. Easy to work out knowing the surface area of Cooriobah and the volume of water from Tewantin.

    How much then needs to flow into Cootharabah ( if Cooriobah's head is above Cootharabah's head). With a larger surface area in Cootharaba,, a flow of water from Cooriobah which reduces its level by say 200mm won't produce a 300mm increase in Cootharaba.

    Furthermore a reduction in level in Cooriobah can be easily mistaken as a tidal peak changing to an ebb even though the tide is still rising at the Tewantin end of Cooriobah.

    If incoming volume of water from Tewantin is minimum( neaps) then the head available in Cooriobah is less than what is usually available. It might even be below Cootharabah's level. The head in Cootharabah and the flow in the 8 km pipeline going past St John's might continue in the same direction irrespective of the tide. So we're not really dealing with predictable tides in pipeline or Cootharaba.

    Once again, the increase in level in Cooriobah caused by the inflow from Cootharaba can easily be mistaken for incoming tide when in fact the tide is ebbing at the Tewantin end of Cootiobah.

    If there are longstanding observations in respect of Cootharaba then things might be different but even if they exist they will be one step removed from tidal predictions which are considered as reliable.
    Last edited by Douglas; 08-12-2018 at 09:13 PM.

  7. #17
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    I think Tony and Paulo are pretty much spot on. Somewhere in the 20 to 30 min window after Tewantin.

    Chewy summed it up pretty well too in another post.
    Cheers
    Gazza

    IF MEN ARE FROM MARS AND WOMEN ARE FROM VENUS, THEN POLITICIANS MUST BE FROM URANUS

 

 
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