Bringing life to a big dam. (fwd)
---------- Forwarded message ----------
Date: Tue, 09 Apr 1996 20:43:51 WST
From: Warwick Rowell <warwick@bettong.EEPO.com.au>
To: Tom Hodges <email@example.com>
Subject: Bringing life to a big dam.
We are currently building a large dam: 10,000,000 litres. In doing
so we are D8ing our way to sterile B horizon soils and beyond. What
can we do to rapidly bring the water and the benthic layer to life?
The dam is nearly at the bottom of our block, with a surface area of
about 4 ha, and an average depth (at the end of summer) of 2.5m.
80 ha of our 140ha site is the only catchment; we are in the wonderful
situation of controlling our own catchment, and having sites where we
can harvest water easily. We estimate that 9% of the 1100mm rainfall
runs off; this is 0.1m x 80 x 10,000 sm = 80,000 cu m, or 80,000,000l
per annum. (1 cu m = 1,000,000 cc = 1000l for the unmetricated!)
As well there are substantial areas of deep clay/sand about 2m underground,
which mean that the dams are continually being recharged from seepage
through the year. Now, before the break of the season, all the 6 small
dams are still full. They are populated with kikuyu, reeds, arum lilies,
tadpoles, and a few marron (a fresh water crayfish that can grow to 2Kg).
Our thinking to date:
1. Let the flushing of the higher dams provide most of the stock.
2. Harvest plants, and replant on islands, and scalloped edges.
3. Add lots of animal manures if available.
4. Add sources of anaerobic bacteria - slime from the bottom of dams.
5. Add lots of duck and geese, with sheds on the island to protect them
6. Load the water up with nutrients to force it into an algal bloom stage
which will then die and provide benthic materials, before adding any
fish stocks. There is an old superphosphate shed that has to be dealt
with... we could probably get 400Kg from there..
Any other thoughts?
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