permaculture

["Australia Felix" <pcorgbgo@bendigo.net.au>]

> Frank asked for ideas on pond building. Maybe we can start a thread on
> this, if anyone is interested. My feedback is below.
> ---------- Forwarded message ----------
> Date: Sun, 1 Aug 1999 22:48:22 -0400 (EDT)
> From: FranksFarm@aol.com
> > In center of pond area is small elevated island with a few trees that
I'd
> > like to keep. How do you suggest we build this pond for wildlife, native
> > plantings, irrigation etc.?

Its pretty difficult in my experience to do all of these things if you
intend using the dam for irrigation - that is unless you are only irrigating
a small area and have a dam that has a capacity that well exceeds this use.
What we do find however is that many native plants do establish themselves
on what is a general water level - regardless of irrigation, seepage (some
people call this leaks !!) and annual evapotranspiration (1300mm/yr in our
area).  These plants are usually brought in by upper catchment inflows and
waterfowl. Another strategy is were we instruct clients to sensitively
harvest seedheads etc. of local riparian species and then simply scatter
them on the water, where eventually wave action will bring them back to
shore where they will naturally find their niche at the appropriate
water/dampness level.

With islands you nearly always compromise dam depth. This can only be
overcome if the dam is large enough for exit and entry batters from the
island to shore to bottom out to a level close to the maximum. As most small
dams dry (or have water used for irrigation) the first thing to appear is a
landbridge between shore and island. What we prefer to do on dams less than
5 Ml is to make penisulas instead. These are easier to construct, have a
similar aesthetic quality and in some areas have the same function.

> --------------------------------------------------------------------------
-
> 1) Get a copy of Mollison's A Designer's Manual

Also "Design and Construction of Small Earth Dams" by KD Nelson, Inkata
Press, Melbourne1985. ISBN 0 909605 34 3; "Farming in Ponds and Dams - An
Introduction to Freshwater Aquaculture in Australia" by Nick Romanowski,
Lothian, Melbourne, 1994, ISBN 0 85091 630 5 (this author has produced many
fine titles that are permaculture-based; "Farm Water Supplies - Planning and
Installation" by Neil Southorn, Inkata Press, Melbourne, 1995, ISBN 0 7506
8912 9; Also any of the PA Yeomans books eg. The Keyline Plan (1954), The
Challenge of Landscape (1958) - my favorite, The City Forest (1971), Water
for Every Farm (1966, 1968 & 1993).

> 2) The pond's edge should be crenelated, i.e. undulating, zigzag,
> ragged, ["lobular embayments" is a term Mollison uses on P.78 of DM]
> rather than a smooth continous curve. See pps. 481-483 of DM on
> "pond configuration and edge effects".

Its OK to try and do this however you are limited by 2 things: the
landscape/shape and money. I would love to do all of those idealised edge
features but at $150/hr its often difficult to do to a budget. Also some of
those features require different machinery. Eg. We would use a dozer to make
most dams and they are capable of creating flowing linear edges. If we would
want to start cutting out different smaller shapes then we might need to
bring in either a backhoe or excavator which generally leave steepish
erodible batters, and require time consuming smoothing of excavated
overburden. If the dam is of a fairly decent size (ie. 5Ml +) then their is
usually enough edge area for a dozer to cut out well battered curves.
(Another point is that dozers are not designed to push material around
tightish corners as it places too great a pressure on some operating parts -
they may appear invincible machines - they're not  and are damn expensive
things to repair). None of Bill's dams at the Tyalgum Institute property had
these features that I remember and I wonder whether any of his clients dams
have either - we need to speculate all options though to return back to the
what's possible - a point often missed....

> 3) Where runoff runs into pond construct a slightly graduated slope with
> different sized pebbles, rocks, gravel, sand - this could become an
> area where shellfish could breed - though usually flowing water is
> necessary - just a thought - maybe divert flow from a creek in and out of
> the pond

Very possible however needs consideration of the flood flow rates to develop
sustainable engineered widths/depths. I find it better to develop drainage
depression into forestry/wetland systems so that we don't have water running
over bare ground and for nutrient/sediment trapping, and then have rocks
then gravels and sands (especially for swimming). Freshwater
shellfish/crustaceans (mussels and yabbies (Cherax destructor) in our area
don't need much encouragement to breed - all they need is mud and detritus.
Local knowledge helps there.

> 4) Construct shallow, boggy, swampy areas for breeding grounds for aquatic
> creatures - plant reeds, cattails and other shallow water aquatic plants
> there (will provide cover for wildlife)
> 5) Make sure you construct areas where the water is shallow to semi
> shallow with rocks, sandbars, etc. for turtles and amphibians, esp. frogs

Sometimes where we have to take out large trees to construct a dam we will
push them out prior to topsoil stripping then push them back into the dam
where they will provide multiple functions.

> 6) You want to be sure you have fertile ground at water's edge - so you'll
> get lush plant growth, weeds, plantings, etc. This is essential for
> wildlife feeding, breeding and cover, and shade in summer and erosion
> control, and nutrient catchment and filtering

By having topsoil stripped as a starting point and then pushing it back over
the excavated areas you will get vegetation coming back after the first few
rains. Also try and make the water level so that it comes onto unexcavated
grass, so that you get shallows/wetlands that resemble a ephemeral
floodplain.
>
> LL
>
> 'Every day the intelligent person learns something new, but every day
> the wise person gives up some certainty'    The Buddha.
>
>
>
>
>
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