best flood control/diversion strategy for river cabin?
December 1, 2015 8:33 AM Subscribe
We have an old log cabin on a river, downstream from a private dam (large manmade lake). Decades ago, a major flood picked up the small house upstream and slammed it against the trees (approx. 1/2 acre) in between, which diverted the floodwaters to either side of our cabin. But what about next time?
One suggestion for diverting floodwaters is to create a gabion retaining wall. This would definitely be the best looking solution, but (after reading The Johnstown Flood, and Isaac's Storm) it seems likely that a strong flood could pick up these boulders, contained or not, and slam them against the cabin. Another idea is to create a weir from sandbags, staggered on the cabin side, maybe covered in some way that would allow making it into a "piano keys weir."
What's the savviest solution here?
One suggestion for diverting floodwaters is to create a gabion retaining wall. This would definitely be the best looking solution, but (after reading The Johnstown Flood, and Isaac's Storm) it seems likely that a strong flood could pick up these boulders, contained or not, and slam them against the cabin. Another idea is to create a weir from sandbags, staggered on the cabin side, maybe covered in some way that would allow making it into a "piano keys weir."
What's the savviest solution here?
Response by poster: Thanks - we will definitely consult with a state expert eventually, but are trying to be as well informed as possible beforehand.
posted by mmiddle at 8:51 AM on December 1, 2015
posted by mmiddle at 8:51 AM on December 1, 2015
Floodwater is an incredibly powerful force, and there are extensive regulations about what you can do in a designated floodway. If enough water was flowing previously to pick up a house, then you could be looking at major expense for a solution that would work to hold back the waters and floating debris. A less drastic option may be to reinforce, make permeable and anchor the cabin so a flood would flow through it and could be cleaned up afterword (including replacing the ruined contents). The advice above about talking to a hydrologist is good and should really be your first step.
posted by meinvt at 10:19 AM on December 1, 2015
posted by meinvt at 10:19 AM on December 1, 2015
Best answer: Hire a hydrologist or some kind of environmental engineer to design/build what's best for you for what you can afford. They will also be familiar with local, state, and federal laws about what you can do to stream banks as well as take into account how what you build can affect structures downstream in the event of high water.
This is the right answer, and needs to be the first step, rather than something you do after picking a random design online. Around here I would start with one of the non-profits that deals with watershed restoration and planning or a faculty member at the local state school in environmental engineering and ask them for names of experts with local knowledge and who specialize in ecologically sensitive design -- there is a lot of really, really bad and heavy-handed river engineering that gets done, often causing expensive fixes later, and there is also a lot of inept work.
You will also almost certainly need to have a meeting with your local planning department (or whatever land use planning agency oversees development in that area) to see what is legal and what is not in the floodplain. Something to consider is that the kinds of engineering you are proposing will require permitting (usually local, state, and federal, but this depends on your location and what you are doing), but lighter touch options like planting and encouraging appropriate vegetation usually does not. If you do go ahead with the design and construction, make sure you hire a specialist contractor with the equipment and knowledge to do river work, rather than someone who normally digs foundations and retaining walls.
There is a lot of liability when you start monkeying with rivers, from downstream residents as well as from public agencies. You don't want to be on the wrong side of that or to inadvertently cause problems for someone else. You are also downstream from a dam, which has its own set of complications -- the hydrograph is obviously not going to be natural and you will need to consider the dam operations and safety in your planning.
posted by Dip Flash at 7:50 PM on December 1, 2015
This is the right answer, and needs to be the first step, rather than something you do after picking a random design online. Around here I would start with one of the non-profits that deals with watershed restoration and planning or a faculty member at the local state school in environmental engineering and ask them for names of experts with local knowledge and who specialize in ecologically sensitive design -- there is a lot of really, really bad and heavy-handed river engineering that gets done, often causing expensive fixes later, and there is also a lot of inept work.
You will also almost certainly need to have a meeting with your local planning department (or whatever land use planning agency oversees development in that area) to see what is legal and what is not in the floodplain. Something to consider is that the kinds of engineering you are proposing will require permitting (usually local, state, and federal, but this depends on your location and what you are doing), but lighter touch options like planting and encouraging appropriate vegetation usually does not. If you do go ahead with the design and construction, make sure you hire a specialist contractor with the equipment and knowledge to do river work, rather than someone who normally digs foundations and retaining walls.
There is a lot of liability when you start monkeying with rivers, from downstream residents as well as from public agencies. You don't want to be on the wrong side of that or to inadvertently cause problems for someone else. You are also downstream from a dam, which has its own set of complications -- the hydrograph is obviously not going to be natural and you will need to consider the dam operations and safety in your planning.
posted by Dip Flash at 7:50 PM on December 1, 2015
Best answer: Chain it to 3 of the largest trees upstream and put some logs under it.
http://www.oregon-floating-homes.com/floating_homes_for_sale_in_portland_oregon_log_floats.htm
Some people use empty milk jugs or styrofoam.
posted by at at 9:51 PM on December 3, 2015
http://www.oregon-floating-homes.com/floating_homes_for_sale_in_portland_oregon_log_floats.htm
Some people use empty milk jugs or styrofoam.
posted by at at 9:51 PM on December 3, 2015
« Older Suggestions for managing charitable clothing... | Help my kitty have a great Christmas roadtrip! Newer »
This thread is closed to new comments.
posted by barchan at 8:45 AM on December 1, 2015 [1 favorite]