Increasing Flood Mitigation Through the Use of Bonus Capacity of Drinking Water Reservoirs

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1 Increasing Flood Mitigation Through the Use of Bonus Capacity of Drinking Water Reservoirs Matthew M. Del Ciello Josh Galster Montclair State University 2016 Passaic River Symposium

2 Factors Affecting Flooding: Urbanization Increased hazard: more impermeable surfaces generates more runoff. Increased human infrastructure increases risk Paterson, NJ. (city-data.com)

3 Factors Affecting Flooding: Climate Change Northeast United States may see an increase in heavy precipitation events. 1 Hurricane strength and frequency may also increase. 2 1 Singh Meehl 2007 Hurricane Irene flooding in Manville, NJ (connect.nj.com)

4 Flooding in New Jersey The floodplain in northern New Jersey is significantly developed and flooding can be especially damaging. 3 Solutions to protect properties have been explored. o Construction of flood control reservoirs and dams met with strong local opposition. o Blue Acres: $50,000,000 for <1,000 homes 3 Huong 2013 Flooding in Paterson, NJ after Hurricane Irene. (NBC)

5 Flooding in New Jersey In 2011, Passaic River Basin Flood Advisory Commission examined flood mitigation solutions: 4 o Improving flood plans o Improving flood warnings o Acquisition of open space o Buying out residences o Elevating structures o Flood tunnel 4 NJDEP 2011 Gov. Chris Christie announcing the Passaic River Basin Flood Advisory Commission. (NorthJersey.com)

6 Flooding in New Jersey Proposed solutions did not include using existing reservoirs. Conflicting interests: o Water resource reservoirs want to be as full as possible. o Flood control reservoirs want to be as empty as possible. Wanaque Reservoir in Passaic County, NJ. (US Forest Service)

7 Utilizing Reservoirs May be possible to fulfill both purposes: o What about using bonus capacity within each reservoir? Bonus Capacity Spruce Run Reservoir in Hunterdon County, NJ (cardcow.com)

8 Utilizing Reservoirs This project examined reservoirs in northern New Jersey to see if their bonus capacities could be used to mitigate flooding. Volumes from 1.8 x 10 7 to 1.3 x 10 8 m 3 Wanaque Reservoir (northjersey.com)

9 Maximum Capacity (m 3 ) Round Valley Reservoir 2.38x10 8 Wanaque Reservoir 1.34x10 8 Lake Hopatcong 7.31x10 7 Spruce Run Reservoir 4.15x10 7 Boonton Reservoir 3.95x10 7 Greenwood Lake 3.31x10 7 Union Lake 3.18x10 7 Lake Tappan 2.39x10 7 Oak Ridge Reservoir 1.85x10 7

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11 Methods 1A. Reservoir runoff calculated using SCS curve number. Precipitation was based on 24-hour storms with recurrence intervals of 5-, 10-, 50-, and 100-years. 1B. Compared that runoff to the bonus capacity. 2A. Estimated volume of water that caused flooding during Hurricane Irene and Lee (2011). 2B. Compared flood volume to available storage capacity of the reservoir. 3. Examined how permeable pavement reduces runoff in reservoir watersheds.

12 NLCD 2011 Land Use Lake Hopatcong Wetlands, CN = 80 Forest, CN = 55 Developed (High Intensity), CN = 95

13 800% Total Runoff Normalized to Bonus Capacity 700% 600% Bonus Capacity Normal Capacity 500% 400% 300% 5-year 10-year 50-year 100-year 200% 100% 0% OAK RIDGE RESERVOIR LAKE TAPPAN GREENWOOD LAKE SPRUCE RUN RESERVOIR LAKE HOPATCONG WANAQUE RESERVOIR

14 Flood Mitigation Do not only need to rely on bonus capacity: o If more space within the reservoir is available during the flood event, why not use it? Only two reservoirs had storage data available: Wanaque Reservoir Lake Hopatcong o Records for both gages start on October 1, Only two major flooding events: o Hurricane Irene (late August 2011). o Tropical Storm Lee (early September 2011).

15 120 Wanaque River Hurricane Irene Flood Event 100 Discharge (m 3 /s) /26 8/27 8/28 8/29 8/30 8/31 9/1 9/2

16 120 Wanaque River Hurricane Irene Flood Event 100 Discharge (m 3 /s) FLOOD /26 8/27 8/28 8/29 8/30 8/31 9/1 9/2

17 Using available storage for flood mitigation Discharge (m 3 /s) FLOOD /26 8/27 8/28 8/29 8/30 8/31 9/1 9/2

18 100% Flood Volume Normalized to Maximum Capacity Percentage of Maximum Capacity 90% 80% 70% 60% 50% 40% 30% 20% Hurricane Irene Tropical Storm Lee 10% 0% 3.42% 2.93% Wanaque Reservoir 0.24% 0.42% Lake Hopatcong

19 100% Flood Volume Normalized to Available Storage Capacity Percentage of Available Storage Capacity 90% 80% 70% 60% 50% 40% 30% 20% 10% 24% 21% 4% 8% Hurricane Irene Tropical Storm Lee 0% Wanaque Reservoir Lake Hopatcong

20 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% Wanaque Reservoir Storage in Percentage of Maximum Capacity (2013) Need less than 6.5% of max capacity to absorb Tropical Storms Irene AND Lee Hurricane Season 0% Dec Jan Mar May Jun Aug Oct Nov Jan

21 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% Lake Hopatcong Storage in Percentage of Maximum Capacity (2013) Need less than 1% of max capacity to absorb Tropical Storms Irene AND Lee Hurricane Season 0% Dec Feb Mar May Jul Aug Oct Dec Jan

22 Permeable Pavement Permeable pavement has CNs between 45 & 89.5 Modelled by reducing CNs for developed lands by 37 percent or 50 percent. o Lowers CN value to allowable minimum. Permeable pavement parking lot (pavestone.com) 5 Bean et al. 2007b Pervious concrete (crmca.com)

23 160% Lake Tappan Total Runoff Normalized to Bonus Capacity 140% 120% 100% 80% 60% 40% 20% Reduced Runoff Original Runoff Reductions are from permeable pavement. 0% 5-year 10-year 50-year 100-year

24 Disadvantages Dams are designed with certain specifications in mind. o Although they can be filled to their maximum capacity, it will wear them down sooner. Overfilling a reservoir can cause erosion at the top of the dam. 6 o Can lead to dam failure VERY bad. o Hazard to residents near the dam and reservoir. Dams and other infrastructure may need to be modified to adapt these strategies. 6 Lima 2015 Failure of the Teton Dam (geol.ucsb.edu)

25 Conclusions Much of the runoff from design storms could be contained by the drinking water reservoirs. The flood waters from Tropical Storms Irene and Irene could have been withheld. Permeable pavement not a strong impact. Increased resiliency, flexibility, and functionality of our flood mitigation resources using existing reservoirs.

26 Thank you. Questions?