Topography and earth
The Columbia River and ancient glacial flooding
have sculpted much of Vancouver’s topography
(landform) by depositing clay, silt, sand, and gravel
onto its banks over tens of thousands of years.
Most of Vancouver is generally flat or terraced,
although areas of steep slopes exist along portions
of the Columbia River, Burnt Bridge Creek,
and Vancouver Lake. Figure 4-2 shows potential
geologic hazard areas in Vancouver. Landslide and
erosion areas include steep slopes, defined as those
greater than 25%.
Air and climate
Vancouver is located in a regional airshed bounded
on the south by Eugene, Oregon, on the north by
Chehalis, Washington, on the west by the Coast
Range, and on the east by the Cascade Mountains.
Regional air quality has improved over the past two
decades, as new emissions controls have generally
kept up with impacts of growth. However, ongoing
scientific research highlighting risks from various
materials has resulted in tightened standards. As of
2010, Clark County ranked in the top 2 percent of
counties nationwide in overall air pollution exposure
according to the Washington Department of
Ecology. Diesel exhaust, primarily from trucks, buses
and small engines has been identified by Ecology
as the most harmful airborne source of pollution to
human health. Car emissions are also a significant
source. In terms of individual pollutants, fine particulate
matter standards were exceeded for 6 days
in 2007 and 2 in 2008. Vancouver has not exceeded
standards for ozone or carbon monoxide on any
days since 1999.
Vancouver has wet, mild winters and warm, dry
summers. The US Environmental Protection
Agency (EPA) projects that Washington temperatures
could increase an average of 4-5 degrees over
the next 100 years due to global climate change,
along with a 10% increase in winter precipitation
levels, and more frequent unusually hot summer
days. Car and truck use is the primary local source
of greenhouse gasses that contribute to global
warming. A detailed inventory of local sources is
available at http://www.cityofvancouver.us/upload/images/PublicWorks/CoV-CommunityInventory-6pager-010810-final.pdf.