The Spiraling Homestead

Tuesday, October 30, 2007

Theory on Drought Monitoring

10/24
I keep mulling this over and just don't know quite how to express it, so here it is anyway. LOL
The articles below point to a term I hadn't heard before, but had been sitting in the back of my mind every time it rained (which it is now).

Impervious Ground Cover. Basically that means anything that keeps water from absorbing into the ground where it falls. This includes roof lines, cement, asphalt. It doesn't even go into the semi impervious of decking, brick walks, etc.

If, as these reports state, most urbanized or urban sprawled areas have 50% of their property - commercial, industrial and private - covered with impervious ground cover, the run off is incredible. At least 40%, right?

The reason I'm saying 40% is that maybe 10% of the water gets absorbed into adjacent ground before it runs off into creeks, storm drains, etc.

However, just as our greenspaces for wildlife are becoming more and more isolated, so is our lands' ability to absorb water for the water tables.

Add the substantial increased use of water by urban sprawl and the earth is in a constant state of drought even when we have "normal" or "average" seasonal rainfall. I understand why meteorologists must report the averages. But I think they need to start taking some additional responsibility in reporting what's needed, how far below normal the water table lies and how people can increase their property's ability to absorb water.

If you think of a bed sheet and you only water in a few spots, it takes a very long time for all of that water to wick throughout the sheet. So goes our property. And, it will dry very quickly, with no reserve to keep it moist, leaving all plants in a constant state of stress.

Ha! I found THE best policy article

It totally substantiates what I'm saying. I've been talking about the great plains aquifer since I lived in Dallas TX 7 years ago. I'm going to try to write a letter to the editor on this subject. If anyone comes up with an eloquent way of saying this in 150 words or less, let me in on it!
Leslie

10/30 Great Blog Post From The Grist.org

Excerpt from article on Shoreland Preservation
Bruce Ferguson, an authority on stormwater management from the University of Georgia,
noted that roads and parking surfaces cover approximately twice the area of their
associated buildings and represent a good 50% of a built up urban area. For this reason
alone, it is important that everyone involved in land development take seriously the
emerging technologies of porous pavement systems.

Study of Salt Lake City area by 'zoning' (V - vegetation, I - Impervious, S - soil and dead vegetation) Figure 5 on Page 5 - very telling.

Study of Atlanta's loss of canopy and gain in impervious cover:
Over the last decade, Metro Atlanta has experienced unprecedented population growth. This change in population has resulted in an increase in impervious surface and a decrease in forest canopy. Overall Metro Atlanta is accumulating 28 acres per day of impervious surface and losing 54 acres of canopy per day, resulting in a ten year loss of 196,921 acres of tree canopy and a gain of 103,273 acres of impervious surface.

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