Abandon Dams...

[kato13]

TrailerParkJawa 01-26-2006, 10:39 PM Has anyone given any thought or knows what would happen to large dams or other large water projects? California lives on its water infrastructure. With the chaos and breakdown of society I wonder what the last actions of dam personal might be.


Would they just open the sluice gates to let water run free? This might kill a lot of people but not doing so could end up causing a greater disaster down the road. Gravity would keep some water projects running but areas where pumps are needed would end up as new lakes.


Any more ideas?

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firewalker 01-26-2006, 10:49 PM can you even do that? just louke the gate's open and leve them,

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TrailerParkJawa 01-26-2006, 11:59 PM can you even do that? just louke the gate's open and leve them,


If the water level behind the dam was running high you'd end up putting a large volume of water down river. If the water level if lower than the gates, say in drought conditions, then nothing would flow.


An abandon dam with its gates closed might end up turning into a giant waterfall or failing during years of heavy rains. A catastrophic failure could conceivably wipe out an entire town or city.

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DeaconR 01-27-2006, 08:23 AM In "Howling Wilderness" the Mississippi's public waterworks are apparently badly damaged and there is no infrastructure to maintain them. I think the area in general is supposed to be badly flooded. Certainly when conducting "Airlords of the Ozarks" you encounter a lot of flooded out areas.

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gstitz 01-27-2006, 11:59 AM Of course, that leads to ALL KINDS of adventure threads...


Marauders/refugees/crazed hermit camped out int he dam support buildings (or even inside the dam - most have tunnels all the way through them)


Nearest town sending an expedition to restore power/stop excessive water flow/relieve drought by increasing water flow...


Heck, just an expedition to salvage equipment...

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ChalkLine 01-27-2006, 06:17 PM Dams come in many flavours, bascially there's some main differences:


- Onstream or Offstream

These days designers prefer offstream dams, it's like having a private lake you can moderate. An offstream dam merely requires you shut down the feedway from the watersource to make safe, which is why the engineers like them as they're intrinsically safer. Onstream is your classic dam cross-flow-wall, and can be for various reasons including irrigation, domestic water supply, level and bank maintenance allowing river traffic (like the barrage at Wloclawek), power supply and many others. They are, as many have said, dangerous in that the river will try and do away with them if not stopped.


- Earth or Concrete

You'd be amazed to know that the vast majority of major 'engineered' dams are earth construction. It has many bonuses compared to concrete apart from the fact that you must over-engineer your dam with much more material than concrete requires. All dams, even concrete, have landform changes on the water store and this is a potential weak point, the concrete dam may maintain integrity but a freak occurance in the earthen reinforcement can wash away the side of the dam creating a new and unexpected sideflow. This is the real danger, that the vast amount of water may suddenly divert and create a new watercourse, probably right into disasterville as they're holding their parade. Even earthen dams will have concrete, metal and brickwork areas tying the topworks together and sheltering it from the rain. Earthen dams appear in flatter, wider areas than concrete dams.


The major problem for a dam is silting and debris-strikes on the dam face, heavy rains may well put sudden pressure on the dam face but that's within design tolerance, but if the upstream debris traps fail you can have a forty-foot tree trunk fly down the river and strike the dam wall like a battering ram, then keep slamming into it. The silting may raise the water level so water consistently flows over the emergency sluice gap, river-born debris will eventually block this and then you have water over the actual dam wall. Now it's bad, the debris will start chipping at the top of the dam wall and the silting will fill up the foot of the water store making the debris path faster. When it fails, the dam washes away and the concrete chunks, millions of tons of water and all that silt suddenly make a break downriver into the catchment. The initial water is faster than everything else, it immobilises evacuation efforts and people being apes they immediately start climbing up rather than scooting away. Then comes the silt mud-slide carrying vast chunks of concrete as well, this will demolish buildings with pressure and the concrete adds the coup-d-gras to any tough structure. There's no swimming in the mud and debris from the wrecked structures, this is a real killer scenario.

If your players are overwintering somewhere, you may want to put a dam upstream, ice adds an extra dimension to all this and if they're unaware of the dam (and townies rarely know where their water comes from) they may have to add quickly to do something or lose everything. If they've been hard cases to the local military, they could well have the soldiers up there planting charges . . .

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