Message-ID: <019701bf6e08$c3b25020$6846cfcf@mallard> Date: Wed, 2 Feb 2000 21:37:27 -0800 From: TomMallard <mailto:mallard@SERV.NET> Subject: Re: Trees & surface storage of water To: mailto:DEVEL-L@LISTSERV.AMERICAN.EDU
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Some species of tree will definitely pump more than you'd like, so shrubs
are typically better at holding the soils, reducing ground level wind and
not using too much water. I'm aware of cottonwoods being big drinkers...a
common desert tree in the western USA along the more permanent streams.
Seepage is also a problem with open reservoirs. In general the deeper the
pool the less the evaporation. Shallow water heats up as well which promotes
photosynthesis and you get algae blooms as a result. This reduced surface
oxygen can prevent fish from growing well. Another problem with rainwater is
that it's not very neutral for pH, so balancing it really helps a lot to
maintain water quality. Leeching of minerals from soils is common in the
desert so the pH may be too alkaline if anything. For the money, a cement
lined, below ground cistern which has easy access and is mainly covered is
likely the best idea. The rebar is probably out of reach for remote
locations, so maybe there just use local fibers to add tensional strength to
the cement.
tom mallard
seattle
----- Original Message -----
From: "Donald Z Osborn" <mailto:osborndo@PILOT.MSU.EDU>
To: <mailto:DEVEL-L@LISTSERV.AMERICAN.EDU>
Sent: Friday, January 28, 2000 9:19 AM
Subject: Trees & surface storage of water
| Surface storage of collected / harvested rainwater in arid climates is
| obviously less expensive than storage in tanks or cisterns, and offers
easier
| access to water than drawing / pumping from wells. However, water loss
due to
| evaporation is likely to be high. Has any work been done on use of trees
for
| windbreaks and shade in order to reduce direct sun, air temperatures, and
wind
| velocity and thus decrease losses from evaporation?
|
| Presumably since trees in proximity to a retention pond might effectively
pump
| a significant amount of water out of it (and probably no amount of
| micro-climate effect could reduce evaporation enough to overcome the
amount
| taken up & transpired by the plants) one would also have to be talking
about
| lining the pond somehow to limit infiltration and the pumping effect.
|
| Thanks in advance!
|
| Donald Zhang Osborn, Ph.D. mailto:osborndo@pilot.msu.edu
| consultant mailto:@ NRMP-Assistant-Mali@icrisatml.org
| ANRM, IK, & ICT in the vernacular mailto:bisharat@go.com
|
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