Thursday, January 15, 2009

Making the most of a dam

The last post outlined our solution to water security. Here is a summary of our priorities relating to dam design and list of the many functions dams can fulfil.

Dams are expensive to build so we recommend thinking through the design/layout, reading widely and studying the topography. If you are thinking of building a dam, here is a checklist of our priorities:-
· Place the dam to protect your house from fire (in fire prone areas)
· Engage a reliable contractor who knows what’s required. Cheapest is not necessarily the best
· Evaporation rates are higher in shallow dams. Incorporate enough depth to tide you over an extended dry break.
· Include some shallow areas around the edges for vegetation and habitat for fish, frogs etc.
· Vegetation around and on the water reduces evaporation and helps settle sediment. This can also be harvested from time to time as valuable biomass for composting.
· Use fences to prevent stock from increasing sedimentation and erosion
· Size the dam according to available catchment- it is no use having a dam that never fills
· Build an outlet into the dam wall so that stale water can be released from deeper levels and environmental flows can be made.

A dam is more than just a water supply. Our dam serves at least 10 different functions making it a very worthwhile investment.
1. Water supply for garden and orchard.
2. Permanent water source for fire fighting.
3. Non flammable static fire break.
4. Dam wall provides a gully crossing point for vehicles.
5. Fish for food and recreation.
6. Swimming and boating.
7. It attracts wildlife which in turn helps us. Wild ducks eat snails, and wallabies keep grass around the dam short and leave fertiliser behind.
8. Micro climate effects- increases humidity.

9. Harvested reeds provide biomass material for composting.
10. Provides many aesthetic qualities and provides private areas for meditative experiences.

Incorporating an island in the dam has some disadvantages. It adds to the construction cost, and the island takes up space that could be occupied with water thus reducing the overall capacity of the dam. However it does have its beneficial aspects.

We included an island because it had aesthetic appeal and provided a safe haven for wild ducks and other birds. It adds extra edge to the dam which increases the potential food supply for fish if the dam is stocked. The island also provides a destination when swimming or boating.


raphael said...

seems veryyyy coooold,:D

Andrew said...

In summer the water is quite warm and we sometimes go swimming to cool off.

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