Tale of Two Cities: Exploring How Two Communities are Using Green Infrastructure to Reduce Flood Risk

Transcription

1 Tale of Two Cities: Exploring How Two Communities are Using Green Infrastructure to Reduce Flood Risk NACo Steering Subcommittees Education Session Lori Cary-Kothera NOAA Coastal Services Center

2 Issue Methodology Impact

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6 Toledo Complaints Summary (2007 through 2012) for Calls Received Regarding Water in Basement and Standing Water in Street

7 We can t afford to keep doing this

8 Green infrastructure

9 But where do we start?

10 Benefits My options Data Costs Tell us

11 Ways we are helping communities 1. Economic assessment 2. Technical assistance 3. Product development

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13 What worked

14 Committed communities

15 Reliable partners

16 Best available data and information

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18 We laid out a path

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20 What we found

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22 Heat map of 2012 damages Let s go for a spin in Google Earth!

23 3 FUTURE CLIMATE CHANGE HEAVY RAIN + PAVED AREAS = DAMAGES Big storms and flooding have increased over the last century and are expected to continue to increase. Climate models are projecting an 8 to 10% increase in big storm events due to climate change. Our project looked at heavy rain in the year Future Chester Creek Watershed could reach up to 1,233* acres or 29%* of land covered in paved materials. Currently 528 acres or 12% of the watershed is covered in paved materials. That s over 700 more acres of paved materials. * Based on Duluth s future land use build out scenario from the comprehensive plan. Acres in Chester Creek Watershed covered in paved material Current Land Future Land The chances of a damaging peak discharge from the 100-year storm event almost doubles! Damages $ $ $ It all adds up and impacts your wallet and your quality of life! $115,000 $420,000 Loss of use $28,000

24 4 INCREASED GREEN INFRASTRUCTURE = DECREASED FLOODING Wetlands and forests help absorb flood water and reduce erosion along stream banks caused by fast-moving flood waters. Chester Creek Watershed is 19.2% wetland and 35.1% forest! Benefits: Reduces peak discharges Captures and reduces a variety of pollutants like sediment, temperature, nutrients, and bacteria Rain Barrels and Cisterns Reduces runoff quantity during storm events Can be designed for public access Green and Blue Roofs Extended Detention Wetlands Retention Ponds Underground Storage Permeable Pavement Stormwater Tree Trenches Bioswales and Rain Gardens

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26 Personal Pledge

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29 Connect with the Digital Coast

30 1 HEAVY RAINS = FLOODING 7.83 inches 6.48 inches (July) 3-6 inches (August) inches (September) 6-10 inches (June) Rain weeks before Steep landscape, water moves fast Soil saturated, couldn t absorb more water Creeks approaching peak fullness Too much water, too fast for storm water pipes Our project is identifying the impacts from a big storm called the 100-year storm. This storm has a 1% chance of occurring every year. Extreme events like the June 2012 flood and the 100-year flood do not happen very often, but when they do, they cause major damages.

31 2 HEAVY RAIN + PAVED AREAS = DAMAGES 5 or more inches in 24 hours. Duluth usually has big storms in the summer and fall. 528 acres or 12% of the watershed is covered in paved materials. Paved areas like parking lots and rooftops do not absorb water, instead they create a potential for flooding because water runs off into either Chester Creek or the storm drains. Storm drains sometimes cannot keep up with the amount of water running off. To help us identify when flooding could occur, we need to know: amount of rain from the 100-year storm information about what s on the land This gives us the peak discharge which is the amount of water moving through Chester Creek at a certain location and time. Damages $ It all adds up and impacts your wallet and your quality of life! $112,000 $400,000 Loss of use $15,000

32 5 YOU CHOOSE! GREEN INFRASTRUCTURE FOR CHESTER CREEK WATERSHED To reduce the damaging 100-year storm peak discharge by 20%, we need to store this amount of storm water: What is an acre-foot? 1 acre-foot = 1 acre of water 1 foot deep OR 326,000 gallons of water. 76 acre-feet needed under current rainfall and land use That s 1,100 swimming pools* *20 ft X 30 ft, 5 ft deep 86 acre-feet needed under future rainfall and land use That s 1,245 swimming pools* How can we reach this goal? The City of Duluth, its homeowners, and businesses can work together to implement different green infrastructure techniques. These techniques will vary in the amount of water storage they provide, but it all adds up to contribute to the goal! Source: Natural Resources Defense Council Risk Reduction With 76 acre-feet of storage, the annual chances of the damaging peak discharge goes down to 0.24% from 1%. With 86 acre-feet of storage, the annual chances of the damaging peak discharge goes down to 0.51% from 1.84%. $1.63 MILLION or $89,000 per year! Over a 20 year time period, the City of Duluth and its citizens will save this much money because they will not have to repair flood damages. Benefits continue to increase as you go beyond the 20-year time period. Reduced Storm Sewer Infrastructure Costs $158,600 Reduced Building Damages $1,029,000 Increased Recreational Use $326,000 Reduced Post Storm Land Restoration Costs $263,400 Don t forget the other benefits: increased property values, improved water quality, wildlife habitat, and more green space in which to play!