Strom: Storm Water Management
UPDATED ACTUAL Questions and
CORRECT Answers
What is the primary consequence of surface changes? - CORRECT ANSWER - developed
sites lose much of their natural storm water storage capacity. The loss of vegetation, organic
litter, and changes in surface characteristics, such as roughness and perviousness, result in the
rapid conversion of rainfall to storm water runoff.
All storm water management practices must be what (3) things? - CORRECT ANSWER -
- site specific
- region specific
- climate specific
Define subsurface runoff - CORRECT ANSWER - is storm water that infiltrates and
moves through the soil both horizontally and vertically. The rate of movement is influenced by
soil permeability and usually occurs at a much slower rate than surface runoff.
When does surface runoff occur? - CORRECT ANSWER - For impervious surfaces,
runoff occurs immediately. For pervious surfaces, the intensity of precipitation must exceed the
infiltration rate, that is, the surface must be saturated before runoff can occur.
What are the environmental impacts from changes in storm water drainage patterns? -
CORRECT ANSWER - - increased flood potential due to increases in peak flow rates
- decreased groundwater supply caused by reduced infiltration
- increased soil erosion and sedimentation brought about by greater runoff volumes and
velocities
- increased petrochemical pollution from street and highway runoff
- contamination of winter runoff by salt and sand in colder regions
, What changes in stream hydrology can result from development? - CORRECT
ANSWER - - peak discharges, which can be as much as two to five times the
predevelopment rate, generally increase the frequency and severity of flooding
- higher velocities coupled with increased imperviousness may also result in reduced stream flow
during extended dry periods caused by reduced infiltration. Groundwater that would normally be
recharged during wet periods and released slowly from soil during dry periods is lost as surface
runoff
- stream geometry also changes. Streams are widened due to increased volume and velocity,
which results in increased stream bank erosion.
- Usually the stream bank is undercut, destabilizing vegetation and, in turn, exacerbating the
erosion problem. Eroded material is deposited in stream channels as sediment, which reduces
stream flow capacity.
- Flood elevations are raised; as noted, this phenomenon increases the extent of the area at risk of
flood damage
Where do contaminants come from? - CORRECT ANSWER - - pollutants are
accumulated on paved surfaces and are flushed from these surfaces during a rainstorm
- contaminants may be released through corrosion, decay, oil and fuel leaks, leaching or wearing
away of construction materials and coatings, brake linings, tires, and catalytic converters.
- developed areas, as well as agricultural areas, contribute herbicides, pesticides, fertilizers,
which stimulate algal growth and reduce the availability of oxygen in water
- fallen leaves and animal poops that would normally decompose in underdeveloped or low-
density settings are more easily washed from paved surfaces, further increasing nutrient and
bacteria levels in streams, ponds, and lakes
Changes in stream hydrology and geometry, combined with reduced water quality, decrease the
value of what? - CORRECT ANSWER - aquatic, stream bank, and floodplain habitats. Not
only are stream channels and flows altered and pollution levels raised, but these conditions are
further exacerbated by low summer flows and higher water temperatures.
How was storm water managed in the past and how is it different now? - CORRECT
ANSWER - - Historically, the primary concern in dealing with storm water runoff was to
remove it as quickly as possible. Traditionally, this was accomplished by conveying runoff by
storm sewers, swales, gutters, and channels to the nearest water body, usually a stream or river.
UPDATED ACTUAL Questions and
CORRECT Answers
What is the primary consequence of surface changes? - CORRECT ANSWER - developed
sites lose much of their natural storm water storage capacity. The loss of vegetation, organic
litter, and changes in surface characteristics, such as roughness and perviousness, result in the
rapid conversion of rainfall to storm water runoff.
All storm water management practices must be what (3) things? - CORRECT ANSWER -
- site specific
- region specific
- climate specific
Define subsurface runoff - CORRECT ANSWER - is storm water that infiltrates and
moves through the soil both horizontally and vertically. The rate of movement is influenced by
soil permeability and usually occurs at a much slower rate than surface runoff.
When does surface runoff occur? - CORRECT ANSWER - For impervious surfaces,
runoff occurs immediately. For pervious surfaces, the intensity of precipitation must exceed the
infiltration rate, that is, the surface must be saturated before runoff can occur.
What are the environmental impacts from changes in storm water drainage patterns? -
CORRECT ANSWER - - increased flood potential due to increases in peak flow rates
- decreased groundwater supply caused by reduced infiltration
- increased soil erosion and sedimentation brought about by greater runoff volumes and
velocities
- increased petrochemical pollution from street and highway runoff
- contamination of winter runoff by salt and sand in colder regions
, What changes in stream hydrology can result from development? - CORRECT
ANSWER - - peak discharges, which can be as much as two to five times the
predevelopment rate, generally increase the frequency and severity of flooding
- higher velocities coupled with increased imperviousness may also result in reduced stream flow
during extended dry periods caused by reduced infiltration. Groundwater that would normally be
recharged during wet periods and released slowly from soil during dry periods is lost as surface
runoff
- stream geometry also changes. Streams are widened due to increased volume and velocity,
which results in increased stream bank erosion.
- Usually the stream bank is undercut, destabilizing vegetation and, in turn, exacerbating the
erosion problem. Eroded material is deposited in stream channels as sediment, which reduces
stream flow capacity.
- Flood elevations are raised; as noted, this phenomenon increases the extent of the area at risk of
flood damage
Where do contaminants come from? - CORRECT ANSWER - - pollutants are
accumulated on paved surfaces and are flushed from these surfaces during a rainstorm
- contaminants may be released through corrosion, decay, oil and fuel leaks, leaching or wearing
away of construction materials and coatings, brake linings, tires, and catalytic converters.
- developed areas, as well as agricultural areas, contribute herbicides, pesticides, fertilizers,
which stimulate algal growth and reduce the availability of oxygen in water
- fallen leaves and animal poops that would normally decompose in underdeveloped or low-
density settings are more easily washed from paved surfaces, further increasing nutrient and
bacteria levels in streams, ponds, and lakes
Changes in stream hydrology and geometry, combined with reduced water quality, decrease the
value of what? - CORRECT ANSWER - aquatic, stream bank, and floodplain habitats. Not
only are stream channels and flows altered and pollution levels raised, but these conditions are
further exacerbated by low summer flows and higher water temperatures.
How was storm water managed in the past and how is it different now? - CORRECT
ANSWER - - Historically, the primary concern in dealing with storm water runoff was to
remove it as quickly as possible. Traditionally, this was accomplished by conveying runoff by
storm sewers, swales, gutters, and channels to the nearest water body, usually a stream or river.
