Class 1

Question 1

what challenges could urban growth have on SW management?

Answer 1

• more impervious surfaces leading to more runoffs
• need for more SW infrastructure
• burden on ground water

Question 2

What are a few issues with taking water out of the ground?

Answer 2

• changes chemical composition of ground water
• changes the pressure beneath ground (less support)
• lowers water tables

Question 3

what are some characteristics of the built landscape that we have consider in SW management?

Answer 3

• no natural resilience
• heat island effect
• messes up the wind pattern
• expensive to maintain
• bad for ecosystems

Question 4

Why do cities draw ground water from agricultural areas?

Answer 4

so that nothing collapses due to the decrease in pressure

Question 5

What are the critical SW thresholds for a stream/

Answer 5

~10& imperv for stream to degrade
~35% imperv stream passes point of no return
~70%+ no longer a stream, just a part of a sewage system

Question 6

Explain the use of the Critical Discharge Rate

Answer 6

• CD rate is the discharge rate associated with flow (in cubic feet/second)
• SW management aims to decrease the # of times runoffs from a storm event exceeds the threshold or minimize the length of time its exceeded.
• exceeding CD rate results in stream erosion and enlargement, stream’s water amount fluctuates greatly between storm and dry.

Question 7

What is baseflow? and how does human development affect it?

Answer 7

• baseflow is the water from the water table that feed the stream system, the flow of the stream when there is no rain.
• humans take water away from ground water so baseflow is lowered.

Question 8

Explain how the urban hydrograph would differ from a rural one

Answer 8

• lower baseflow
• higher and more rapid peak discharge
• more runoff volume
• steep recession

Question 9

what is the 4-stage multi-level strategy?

Answer 9

• policies and source controls
• site BMPs (i.e. greenroofs)
• community BMPs (i.e. vegetation strip in the middle of the road)
• watershed-level

Question 10

What are some challenges for SW management at the watershed level?

Answer 10

• there could be several towns within one watershed, hard to agree on stuff.
• there is a series of plans for each township in the watershed plan

Question 11

What national policies for SW management are there in Canada?

Answer 11

-we dont have any specific ones, but mainly we follow Canada Fisheries Act, CEPA, Recreational water quality guidelines and such.

Question 12

What is the hierarchy of SWMPs?

Answer 12

SW lot level (source) controls>SW conveyance controls>end of pipe SW facilities