How do I measure tidal flow volume?

I'm trying to get some figures on tidal water volume that flows in/out of a marina for a project that is required to try and fix an environmental disaster. The opening is 103mtrs wide and average depth is about 4-5mtrs (will get more accuracy when I know the formula for the maths). It's midwest coast tides and I need the volume of water from low tide to high tide as it passes the entry point. Would anyone in the Fishwrecked brains trust know how to calculate that? Cheers.

Posts: 28

Date Joined: 06/12/16

 Send me a PM with more

Fri, 2021-09-03 21:27

 Send me a PM with more details and I can probably help you out.

Posts: 589

Date Joined: 18/04/08

Cheers CD

Fri, 2021-09-03 22:48

PM sent, hope you can help mate, it's a pretty bad situation.

Pete F's picture

Posts: 154

Date Joined: 07/01/18

 You need to know the area of

Sat, 2021-09-04 01:41

 You need to know the area of the marina x depth of the tide change. Then it would be if that size opening could handle the volume in the time frame.



Posts: 589

Date Joined: 18/04/08

,Area is 160,000 Square mtrs

Sat, 2021-09-04 02:11

Depth of tide change at max high/low  approx. 600mm. Now this can be easily worked out in a river with constant flow but tides run at different speeds from start to finish but if I can work out how much water is flowing in mid tide or the maximum flow rate that would suffice. Thanks.

Edit: The idea is to stop the natural incoming tide coming through the entrance and creating a new clean source of water/aeration as a man made tide

Rob H's picture

Posts: 5338

Date Joined: 18/01/12

 as someone said above, if

Sun, 2021-09-05 19:19

 as someone said above, if the area is 160,000 sq meters and a tide movement of 600mm that makes 96000 cubic meters of water each tide movement (6 hrs 20)

If the water average depth is 5 meters it holds 800,000 cubic meters.


 Give a man a mask, and he'll show you his true face...



The older you get the more you realize that no one has a f++king clue what they're doing.

Everyone's just winging it.


sea-kem's picture

Posts: 13575

Date Joined: 30/11/09

 Jurien Bay?

Sat, 2021-09-04 08:28

 Jurien Bay?


Love the West!

Posts: 589

Date Joined: 18/04/08


Sat, 2021-09-04 11:14

Sure is.

sea-kem's picture

Posts: 13575

Date Joined: 30/11/09

 I've been reading a bit

Sat, 2021-09-04 14:37

 I've been reading a bit about this lately, seems to be a major problem up there. 


Love the West!

Posts: 111

Date Joined: 30/06/20

 Exactly what I was thinking

Sat, 2021-09-04 22:35

 Exactly what I was thinking


 More of a fisherman than a catcherman

Posts: 11

Date Joined: 13/08/20

Hey Fathom, might be able to

Mon, 2021-09-06 08:12

Hey Fathom, might be able to help you out - I work for a company that does this sort of stuff commercially. contact me via PM and we can have a chat if you want. Its a project close to my heart, so would be happy to be involved



Posts: 589

Date Joined: 18/04/08

Marina Restoration

Tue, 2021-09-07 23:29

Officially It's named by Departement of Transport as: Jurien Bay Boat Harbour (JBBH)

Construction was never finished to origanal plan? I'd like to see a copy of the original plan if anyone has one please.

Did a team of designers for the "JBBH" finally realise they just created a huge weed funnel? Dropped tools and ran away?

Heres some old vid of some old  blokes in old suits talking about the old subject, for those needing more info:

Latest info  from DOT:


Thanks for the responses you mob, it really is appreciated. WA, we have a problem ... there is a "rally" being held at the marina (Boat Harbour) this Saturday 10AM I've heard, you might find details on facebook?

I'll respond a bit more later.....meanwhile to keep yo entertained here is some more JBBH CRAB action:



Posts: 903

Date Joined: 19/06/14

Good luck with the rally.

Wed, 2021-09-08 06:54

 DOT and Allanah Mc Tiernan are tits on a bull. Just look at the Fascine in C'von. Almost six years since the Fascine debarcle and there's still no access for any boat with a decent draft into the Marina or boat ramp. Appalling.


 My wife understands why I clean my rods n reels in the shower....