Environmental Engineering Reference
In-Depth Information
TABLE 12.2
Ecosystem Impacts across Major Engineered Systems in Urban Watersheds
Sanitary
Sewers
Overland
Flow
Navigation/
Flood Control
System Impact
Water Supply
Stormwater
Reduction
Loss of land
Loss of land
Loss of riparian
habitat
Loss of land
Loss of riparian
habitat
Fragmentation
Minimal
Minimal
Detention
ponds
interrupt
habitat
corridors for
terrestrial
species
Roads create
habitat
patches too
small to
support some
species
Streams are
split by dams;
sedimentation
occurs
Substitution
Minimal, unless
withdrawals
cause stream
temperature to
rise
Minimal
“Rough fish”
replace fish
with higher
oxygen
requirements
Loss of
dissolved
oxygen in
streams
Creates access
problems for
waterfowl;
other species
may move in
Simplification
As above with
substitution
Minimal
Decline in
species
diversity in
the receiving
waters
Decline in
species
diversity in
the receiving
waters
Dams can block
fish migrations
Contamination
Leaking landfills
Infiltration/
Inflow
Delivery of
heavy metals
to water
bodies
Pathogens
delivered to
water bodies
Removal of
bankside
vegetation can
allow more
pollutants to
enter streams
Overgrowth
Minimal
Sewer
overflows
induce the
growth of
macrophytes
Cultural
eutrophication
from
increased
input of
phosphorus
Excess
nitrogen and
phosphorus
are carried to
streams and
lakes
As above with
contamination
rain water that should have been directed to the storm sewer. When too much of this clear
water mixes with untreated sewage, the volume flowing through the sewer pipes may
exceed the capacity of the sanitary sewer system pipes. This condition can produce sewer
overflows into basements or streets.
Stormwater . Consists of storm drains of different types, for example, culverts, field tiles,
and buried storm sewer pipes. Constructed wetlands and ponds for detention, reten-
tion, or infiltration are included, along with the weirs accompanying some of these
implementations.
Result: The open components of stormwater control systems (e.g., detention ponds) and
the untreated discharge from pipes create significant ecosystem impacts. Detention ponds
consume valuable property and require ongoing maintenance to function properly. Poorly
timed discharges from detention pond networks have exacerbated local floods (Debo and
Ruby 1982). Contaminants in stormwater can affect riparian habitat and lead to species
substitution. Rough fish, such as carp, may replace trout and other species requiring a
 
Search WWH ::




Custom Search