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  • From: Permacltur@aol.com
  • To: "permaculture" <permaculture@franklin.oit.unc.edu>
  • Subject: Re: Storage of Flood Water on Farmland (fwd)
  • Date: Sat, 25 Sep 1999 16:13:20 EDT

There are a number of strategies for storing water on land, including
farmland, all well developed through permaculture.
The first strategy is to intercept water in high areas through a variety
of measures. The principle measure would be, where land is sutable for
cultivation, to develop keyline cultivation practices. This stores water in
the ground, reducing or eliminating runoff, and thus limiting or eliminating
flooding in low areas. Sometimes these are on the same parcel. This
approache is well described in Water for Every Farm by P. A. Yeomans, as
updated by Ken Yeomans. A close second is the interception of high runoff by
diversion drains to high ponds created by saddle dams, contour dams, and
such. This is described well in Permaculture Design Course Pamphlet III,
Permaculture for Humid Landscapes by Bill Mollison. These techniques store
water that would be flood waters at the highest possible points on the
landscape. Where water is held in soil, local hydrology is enhanced and dry
springs begin to run again. Where water is held in dams, some percolation
also takes place, but mainly the water is held for irrigation during dry
periods or for other uses where gavity feed provides great utility. If one
waits until the water has reached a low point, it has had maximum opportunity
to cause opportunity and takes maximum energy to move to a useful place.
In land of gentle contours and in low lands, swales are a secondary
strategy. The swales hold flood waters with the expressed intent of
recharging ground water. I have used this technique in semi-arid places,
even, to catch downpours permit percolation laterally into adjacent beds in
production. In effect, the asiles between beds (on contour) double as
swales. This was very effective. It is written up in The International
Permaculture Solutions Journal, Vol. I, No. 3, as "dryland chinampas."
Swales can be planted to species that tolerate flooding from time to time
including some cultivated species of hawthorn (e.g. mayhaw), jujube,
elderbery, and certain species grown for firewood or biomas, such as alder,
willow, etc. Larger swales can be planted to paddi rice that tolerates
upland conditions, such as M101, so that it will grow either while flooded or
as if in upland conditons.
By adopting Asian water buffalo to replace Bos genus cattle, flooded
pasture land is fine pasture land. There are species of perennial grasses
that grow on dry land or as emergent species under water. Waterfowl
obviously are addtional animal species to consider to raise on such farms.
Both geese and ducks feed under water and forage crops such as chuffa will
produce well in lowland areas, serving as emergent crops if the water does
not get too deep. If one has some portion of the land dug deep enough to
always hold water, than plant and animal species can migrate quickly to
flooded areas. Mosquito fish operate in well under an inch of water and help
control the mosquitos during flood periods. Azolla should be grown in such
biological reserve ponds, and duck weed, so that they can rapidly expand when
conditions allow. This strategy is inappropriate where flooding is due to
cold spring melt-off, however. Depending on duration of flood waters, such
cold waters could grow trout, native catfish, buffalo fish, etc. Note that
annual flooding with a crawfish harvest alternated with plant crops is a well
established mainstream practice in Louisana where they benefit from a cycle
of Winter rains and summer dry periods. This is well documented in extension
documents from Louisiana. Along the Gulf states, bald cypress and crawfish
farming produce a semi-aquatic agroforestry. Crawfish provide many of the
same services in water that earthworms do on land. They grow from Canada to
the tropics, with care in species selection.
Even chickens can be managed to take advantage of flooding.
Air-breathing invetebrates concentrate at the edge of the advancing flood
waters and chicken on free range quickly learn to harvest them. Ducks would
do well also. Retreating flood waters generally leaves a wet edge full of
crawfish which pigs and ducks can harvest (if they get there ahead of the
wild pigs and racoons).
Finally, the ultimate approach in such areas is the development of
chinampas, specially made raised beds which extend above the flood limit (in
most cases) and grow crops. Channels developed in the construction of
chinampas (built of alternating layers of vegetable matter and mucky soil)
are very useful in aquaculture. By having some channels "blind", meaning cut
off from the others by chinampas beds, species can be grown in one channel
that is incompatible with species in others. For example, one would prefer
to keep catfish out of channels in which crawfish are to be harvested
directly (not as catfish). Chinampas are extremely high yield, when
surrounded by flood waters exhibit moderation due to thermal mass and phase
change energies (evaporation and condensation), have elevated light levels
due to reflected light from water, never need irrigation, and lend to simple
movement of harvest by boat. Beneficial edge effects are very high.
In sites such as Barking Frogs Permaculture Center here in Florida, we
plan to time fish harvest with diminishing water tables. (That is also the
strategy of the wild predators, so some crop will go in that direction.)
We are presently in process of designing and testing stategies suited to
rather random flooding (the last being a 7-foot rise in the water table
during the "dry" winter season of 1997-1998 that just recently returned to
normal levels.) Water buffalo, which are the prime strategy, are as yet
outside our budget. By eating rampant floating weeds they would increase
fish production by orders of magnitude. The light penetrating the water
would stimulate algae production which would release oxygen. At the moment,
oxygen levels are so low that even crawfish production is limited (which is
probably one reason why they invade freshly flooded land so
rapidly--uncovered water means higher oxygen content plus an abundance of
food, decaying plant matter.) We are also looking at pigs because the
turnaround timne is short so herd size can be quickly adapted to reflect
forage conditions. Pigs WILL root in water of up to 3 inches--at least the
feral pigs around here do. We have been hesitant regarding waterfowl because
of the liklihood of predation by alligators and because it would be difficult
to prevent escape. On the other hand, my wife is seriously interested in
investigating gator farming. Sort of solves the racoon problem, but round-up
could be hell. (We remove about a racoon a week, on average, which seems to
be a steady-state situation--still plenty of racoons. There is another cash
crop--pelts--for someone who wants to bother.)
A major problem on flooded pasture is that we seem to loose almost all
our legumes for fixing nitrogen. Supression of nematodes by flooding is a
somewhat compensatory benefit as is the fertilization by stranded floating
plants and detritus, notably azolla which gives a bump in production for a
few years.
I guess flooding that is reliably seasonal would be a fairly simple
design problem--here it is random, though the greatest liklihood over a
millenium would probably be the fall months of hurricane season. Still it is
hit or miss on a year-to-year basis.
There are of course many more design considerations in flooded land,
including access for livestock, people and crops, potential for plant
diseases of certain crops promoted by anerobic conditions, and even
prevailing wind direction. Here we benefit from being at the East edge of a
large floodable area. With our winds very commonly from the West, we get
deposits of nutrient-bearing floating detritus and plants during flood cycles
that has made our side of the wetlands far more fertil than the far shore.
Wind can build up a fair bit over open flooded areas and we are developing
shelter belts of bald cypress (adimittedly for future generations) and hybrid
willow to deal with this. We have also found one species of bamboo that
persisted under water for months and still thrives.
Well this is a very fertile area for productive design, but maybe these
starter notes will jar a few thoughs loose.


For Mother Earth, Dan Hemenway, Yankee Permaculture Publications (since
1982), Elfin Permaculture workshops, lectures, Permaculture Design Courses,
consulting and permaculture designs (since 1981), and annual correspondence
courses via email. Copyright, 1999, Dan & Cynthia Hemenway, P.O. Box 52,
Sparr FL 32192 USA Internships. YankeePerm@aol.com

We don't have time to rush.

A list by topic of all Yankee Permaculture titles may be found at
http://csf.colorado.edu/perma/ypc_catalog.html
Elfin Permaculture programs are listed at the Eastern Permaculture Teachers
assn home page: http://home.ptd.net/~artrod/epta/eptahmp.html
----------
In a message dated 9/25/99 1:57:17 PM, london@metalab.unc.edu writes:

<<-------- Forwarded message ----------
Date: Fri, 24 Sep 1999 14:32:14 -0400
From: Crosswhite.William@epamail.epa.gov
To: sanet-mg@ces.ncsu.edu
Cc: Manale.Andrew@epamail.epa.gov
Subject: Storage of Flood Water on Farmland



Short-Term Storage of Flood Water on Farmland

A colleague is developing and examining the idea that the benefits of
short-term
storage and management of flood water on farmland may be much greater than
the
associated costs. This storage would supplement the storage that is already
available in COE and Small Watershed structures. If large amounts of flood
water could be stored on farmland, the effective operation of all these
activities should be closely coordinated. I include a summary of the idea
and a
request.

Summary

Short-term storage of flood waters by the temporary plugging of ditches and
drainage systems and holding water on farmland with berms around the edge of
fields and other actions could reduce the social and environmental cost
associated with downstream flood impacts. In return, farmers would be paid an
amount that would cover the opportunity cost of the land for the period of
runoff storage including crop loss and any other related costs. Additionally,
there could be cost sharing of installing berms and risers to store water on
the
surface, gates to retain water in drainage ditches, and modifications to
drainage systems to temporarily store water in drainage pipes and the soil.

Request

First, I solicit and welcome comments on (1) the feasibility of storing and
managing runoff on farmland and (2) any suggestions and ideas on ways that can
be used to provide short-term storage of water on farmland.

Second, if you have installed berms and risers, gates in drainage ditches,
controlled drainage and subirrigation systems, or other systems that would
provide short-term storage of water on farmland, please share information on
the
costs associated with these systems in as much detail as is available.

Thank you very much for the information and ideas you share. Publications and
other materials welcomed.

William Crosswhite
USEPA Mail code 2121
401 M Street SW
Washington, DC 20460

202-260-6804
Fax 202-260-2300



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