hy there, I own 30 hectares in the Paraná river delta, in Argentina and the phreatic zone is almost at the surfice in most of the property and it gets higher seasonably. How does Permaculture deals with this pecularity? if I see this as a problem, how would you sugest I get the phreatic level down? I'm sure there must be solutions, right? the typical answear the locals give to this problem is to bring sand from outside by ships, wich is very expensive and the end result is you are covering rich aluvial soil with sand... I would rather do something the permacultural way obviously, but what?
I live in a subtropical zone with a high water table and periodic flooding. Coastal river flood plain. Drainage is not great with a monsoonal type rain putting parts of the yard an inch underwater. Oursolution has been to use hugelkulture to raise the level of the yard rather than do anything about the water table. In the orchard we've planted tropical fruit that can stand wet feet for short perids of time. The property has an advanced banana plantation on it that is now being thinned and the felled banana vegetation is recycled as mulch in hugelbeds. Plants needing good drainage are grown in large containers raised off theground or in hugelbeds with a lot of woody material underneath to keep the plant roots out of any standing water. Garden beds are created with a hugel bed 1-2ft deep that composts down to be slightly raised above the existing ground level. Over time this raises the property and makes it less prone to flooding. The life in the soil s very good with huge earthwrms literally jumping around in the soil when they are uncovered.
You are right dumping tonnes of sand onto alluvial soil makes no sense. Much of the material used for the hugel beds comes from the property making it veery cost effective.. We've also decided to grow quasi-aquatic plants in the boggy areas like water chestnut, arrowhead and sedge plants.. The result has been a frog frendly habitat and loads more dragonflies in the garden. We've used duckweed and other matting floating plants tokerp mosquito larvae out of the standing water on the property.
Bananas are a great pioneer plant being fast growing, fibrous, quick to fruit and die giving you lots of organic matter to compost. A banana plant is a biennial that can withtand a lot of water. None of the floods here have ever killed them. They offer protection from winds and filtered light perfect for growing other crops. Tamarillo seems o be oing ell here too. We planted it on a high part of the property and created a drainge dirtch around it to allow water to drain.
posted 7 years ago
You might also want to investigte vetiver. Vetiver hedges can be used to trap silt and organic matter and over time create a natural terrace if planted on a slope. Check out the vetiver.org site or lots of research on various uses O think I rember something there about altering water table levels..
You may be able to increase the rate water is transpired to the atmosphere with species like Taxodium distichum (bald cypress) and Nyssa Aquatica (water tupelo). These are common in the wetlands of the United States, and I'm sure there are trees in South America that fulfill a similar function. If you provide a place for the water to collect, say a channel to a constructed wetland, and then plant that wetland with these water loving species, you may end up with the best of both: reclaimed land, and a smaller wetland with a more stable year round water level.
posted 7 years ago
oh, thank you so much fellows, really usefull insights! thank you thank you thank you. I am resarching the Chinampas of the Asteks also and it seems to be really adecuate. I just looked up that vetiver (vetiveria zizanioides) plant and it looks very interesting too. Really, thank you, very very much