Reducing Urban Runoff

Anthropocene: Unit 4

5.13 Reducing Urban Runoff

Objectives, EKS, and Skill

  • Suggested Skill:
    • 4.B Scientific Experiments: Identify a research method, design, and/or measure used.
  • Learning Objective:
    • STB-1.B: Describe methods for mitigating problems related to urban runoff.
  • Essential Knowledge:
    • STB-1.B.1: Methods to increase water infiltration include replacing traditional pavement with permeable pavement, planting trees, increased use of public transportation, and building up, not out.
    • Mitigate = reduce

Environmental Consequences of Urban Runoff

  • Decreased infiltration (groundwater recharge)
  • Rain washes pollutants into storm drains & into local surface waters:
    • Pollutants & effects
      • Salt (plant & insect death)
      • Sediment (turbidity)
      • Fertilizer (eutrophication)
      • Pesticides (kill non-target species)
      • Oil & gasoline (suffocate fish/kill aquatic insects)

Solution: Permeable Pavement

  • Specially designed to allow stormwater to infiltrate & recharge groundwater
  • Decreases runoff, decreasing pollutants carried into storm drains & into local surface water
  • Decreases likelihood of flooding during heavy rainfall
  • More costly than traditional pavement

Solution: Rain Garden

  • Gardens planted in urban areas, especially surrounding a storm drain
  • Decreases runoff by allowing it to soak into garden soil surrounding storm drain
  • Decreases likelihood of flooding during heavy rainfall
  • Creates habitat for pollinators, sense of place & stores CO2CO_2

Solution: Public Transit

  • More cars on the road = more pollutants on streets to runoff into storm drains & local waters
    • Motor Oil
    • Gasoline
    • Tire pieces
    • Antifreeze
  • More cars = more lanes & parking lots (impervious surfaces) & more stormwater runoff
  • Public transit decreases urban runoff, pollutants on road, CO2CO_2 emissions & even traffic!

Solution: Building Up, Not Out

  • Building vertically decreases impervious surfaces (decreasing urban runoff)
  • Can be combined with “green roof” or rooftop gardens to further decrease runoff
  • Green roof also sequesters CO2CO_2 and filters air pollutants out
    • Plants absorb NO2NO_2, PM, & other pollutants into stomata & store in tissue or soil

Practice FRQ 5.13

  • Design an investigation to measure the relationship between the number of trees in a city and the amount of stormwater runoff the city produces
    • a) Propose a hypothesis for your investigation.
    • b) Outline a procedure for your investigation.
    • c) Identify your independent variable.
    • d) Identify your dependent variable