Talk:Oesterdam

Construction

"Construction began after the completion of the Markiezaatskade dam (1981 - 1983), the tidal effects of the completed dam making the construction of the Oesterdam easier."

How so? My understanding from reading various articles on the Delta Works is that every time a body of water was compartmentalized, that the ebb-and-flow on the seaward side of these dams increased. I see how the Markiezaatskade would make construction of the Oesterdam easier, logistically, but I think I may not be understanding why it helped with tidal changes. Criticalthinker (talk) 09:00, 8 February 2024 (UTC)

Indeed the tidal range at the sea side of the Markiezaatskade increased somewhat, but because the storage area behind the new Oesterdam became much smaller, also the currents in the closure gap became smaller, and therefore closure became easier. Because of the decreases current speed a sand closure became possible, which was much. cheaper than a closure with rock or caissons. HJVerhagen (talk) 14:49, 8 February 2024 (UTC)

Are you basically saying that while the construction of the Markiezaatskade INCREASED the tidal range, the benefit to the construction of the Ooesterdam construction was that it DECREASED the tidal speed/current? If this is the case, I think this kind of basic information might be useful to add to the various articles on the Delta Works, because it's not necessarily obvious to someone encountering this kind of engineering for the first time. For instance, I still do not understand how the construction of the Zandkreekdam helped in the construction of the Veerse Gatdam. I realize this kind of engineering has complicated details, but perhaps there is a sentence or two when it's brought up how the secondary dams helped in the construction of the primary dams why that was. The tide scours regardless of which side of an inlet you close first. Criticalthinker (talk) 06:08, 15 February 2024 (UTC)

It is not the case that always a dam will decrease speed and increase tidal range. It depends very much on the exact geometry of the various tidal channels and the phase differences of the tide at both side of the channel. If, in case of Veerse Gat, the Zandkreek was not closed, there would be two problems: the total area of (what is now) Veerse Meer would be filled via Zandkreek, increasing the speed in this channel considerably, causing a lot of unwanted currents and erosion around this channel. Also closing Veerse Gat would be more difficult. Realise that the tidal wave moves faster in deeper water, so the top of he tidal wave arrives at Zandkreek earlier via Oosterschelde than via Veerse Meer. Because of this, without Zandkreek dam more water would flow through Veerse Gat.

Computing the exact velocities in all this channels is complicated. The differential equation describing the water movement can only be solved by some linearisation, and then still you have s=to solve them numerically. Before the available of digital computers this was nearly impossible. (The main mathematics were developed by Hendrik Lorentz for the closure of the Afsluitdijk, but he needed a whole team of (human) computers to solve a simplified version).

Therefore around 1955, when there was a need to predict the change of velocities due to closure works some (very large) physical hydraulic were build, but the suffered from scaling laws. Johan van Veen suggested to use analogue computers, the worked well but were very large (see Deltar). But only after reliable fast digital computers became available (around 1980) predictions of currents in closing gaps were sufficiently accurate to go for closures using sand only. HJVerhagen (talk) 20:23, 15 February 2024 (UTC)

"Also closing Veerse Gat would be more difficult. Realise that the tidal wave moves faster in deeper water, so the top of he tidal wave arrives at Zandkreek earlier via Oosterschelde than via Veerse Meer. Because of this, without Zandkreek dam more water would flow through Veerse Gat."

HJVerHagen, just so I clearly understand, you are saying that the water is deeper along the north shore of Noord-Beveland than in the connected Veerse Gat-Zandkreek, so that before the holes were closed the tide reached the eastern end of the Zandkreek more quickly than it went through the connected Veerse Gat-Zandkreek? So to put it more simply, the wantij developed at the eastern end of the Zandkreek?--Criticalthinker (talk) 04:21, 29 March 2024 (UTC)