Friday, November 27, 2009
About Water- Part 1
The balmy climate of Southern California has been attracting people for over 200 years. A sunny day is guaranteed at about 300 days a year, and rain only occurs during a few winter months. And although that’s one of the main attractions of the region, it’s also one of the main problems:
The city of Los Angeles receives about 14-15 inches of rain throughout the year- approximately the same as the city of Denver- but while Denver gets it more evenly spread throughout the year, we get it in a few short months. When the region was still largely unpopulated, this was not an issue- Rain fell on the ground, soaked the soil and eventually made its way into the many seasonal streams, such as the Arroyo Seco or the Los Angeles River. Those rivers were dry at the surface for most of the year- maintaining only an underground flow- but transformed themselves into raging streams during the rainy season.
With the increased development of the LA area, percolation surface became rare- the roofs of houses, streets, parking areas and walkways have been taken away from the percolation area and transformed into water collectors. City codes require roof water to be conducted to the street and the storm drain system and diverting a significant amount of rainwater from the land to the ocean.
Now, with out cities almost built up, not a lot of open percolation area is left. Every drop of water that hits a roof goes to the ocean. We’re running out of ground water, because we directed it into the salty Pacific. At the same time, the patchy storm drain network, especially in hillside areas, directs the flash-flood like water volumes in many places from the streets into earthen canyons, undermining roadways, homes, infrastructure and causing millions of dollars in property damage that would be avoidable.
Therefore, any sustainable home design approach needs to address the issue of rainwater retention and its use on site. Slow infiltration locally will lower the demand for imported irrigation water and reduce the cost of repair for erosion damaged roadways and foundations, thus saving millions of dollars for already strained municipal budgets.
The Nob Hill Haus will take on this challenge on all levels by reducing the amount of water needed to operate the house and garden while at the same time reducing the amount of water released to the strom drain system and increase safe on-site percolation.