Does Too What is at Risk when Groundwater Rises? Jayne F. Knott - - PowerPoint PPT Presentation

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Does Too What is at Risk when Groundwater Rises? Jayne F. Knott - - PowerPoint PPT Presentation

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As Sea Level Rises Groundwater Does Too What is at Risk when Groundwater Rises? Jayne F. Knott and Jennifer M. Jacobs University of New Hampshire Department of Civil and Environmental Engineering Hosted by NH Coastal Adaptation Workgroup

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As Sea Level Rises Groundwater Does Too – What is at Risk when Groundwater Rises?

Jayne F. Knott and Jennifer M. Jacobs University of New Hampshire Department of Civil and Environmental Engineering Hosted by NH Coastal Adaptation Workgroup (NH CAW)

April 26, 2018

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Outline

  • Introduction - Groundwater
  • Sea level rise (SLR) and coastal groundwater
  • SLR in coastal New Hampshire (NH)
  • Simulated SLR-induced groundwater rise
  • Potential impacts of groundwater rise
  • What can we do?

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Introduction - Groundwater

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Water Volumes (km3)

96% 2% 1%

Fresh

Charles Harvey, CEE-1.72 Groundwater Hydrology, Fall 2005. (Massachusetts Institute of Technology: MIT OpenCourseWare), http://ocw.mit.edu (Accessed April 2, 2018). License: Creative Commons BY-NC-SA

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Hydrologic Cycle with Annual Volumes (thousand km3/year)

Charles Harvey, CEE-1.72 Groundwater Hydrology, Fall 2005. (Massachusetts Institute of Technology: MIT OpenCourseWare), http://ocw.mit.edu (Accessed April 2, 2018). License: Creative Commons BY-NC-SA

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Sea level rise and coastal groundwater

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Sea level is rising

Griggs, David. Climate Change 2001, Synthesis report, Contribution of working groups I, II, and III to the Third Assessment Report of the Intergovernmental Panel on Climate Change, Cambridge University Press, 2001

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Union of Concerned Scientists, 2015; www.ucsusa.org/sealevelrisescience

Surface water impacts of sea level rise What’s happening UNDERGROUND?

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A more complete picture

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http://www.skagitclimatescience.org/skagit-impacts/sea-level-rise/ Seattle, Washington

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Can a sea wall really keep the water out? Groundwater flow

Charles Harvey, CEE-1.72 Groundwater Hydrology, Fall 2005. (Massachusetts Institute of Technology: MIT OpenCourseWare), http://ocw.mit.edu (Accessed April 2, 2018). License: Creative Commons BY-NC-SA

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Has Groundwater Rise been Recorded? Yes - Cape Cod

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McCobb and Weiskel (2003)

2.1 mm/yr. average GW rise in a well 300 m from coast in Truro, Cape Cod 2.5 mm/yr. average sea-level rise at the Boston tide gage.

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Groundwater will rise with sea level rise – Why do we care?

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Source: U.S. Geological Survey

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Groundwater contamination from septic tanks

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Source: https://www.mass.gov/service-details/smart-growth-smart-energy-toolkit- modules-wastewater-alternatives Vertical separation between the bottom of leaching field and groundwater decreases – total treatment decreases because there is less vertical passage.

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Groundwater rise and septic systems: North Carolina

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Source: Manda et al. (2015)

Current seasonal high water table Seasonal high water table with 1.0 m SLR RED - Simulated GW is above the leaching field trench

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Rising groundwater can mobilize contamination from disposal sites

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Plummer, McGeary, Carlson. Physical Geology, 8th ed., McGraw-Hill Companies, Inc., 1999

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What will happen to the freshwater/saltwater interface? Will it move inland?

Source: U.S. Geological Survey

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Saltwater Intrusion into Drinking Water Wells

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2007 Thompson Higher Education; https://www.slideshare.net/prashantpkatti/sea-water-intrusion

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Sea-Level Rise in Coastal New Hampshire

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NH Sea-Level Rise Situational Awareness

NH Coastal Risk and Hazards Commission NH Dept. of Environmental Services NH Coastal Adaptation Workgroup

Photo Credit: Peter Digeronimo

CAW King Tide Photo Competition November 5-7, 2017

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NH Sea-Level Rise – Projected Tidal Flooding

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Note: Storm surge = flood extent from a 100-year/1% chance storm event Tidal water inundation with SLR Green shading = 0.5 m, 1.2 m, and 1.9 m of SLR Tidal water inundation with SLR and storm surge Pink shading = 0.5 m, 1.2 m, and 1.9 m of SLR

Map credit: Tides to Storms, Rockingham Planning Commission (2015)

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New Hampshire Seacoast What is coastal and what is inland?

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How far inland will the effects of SLR be felt?

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Simulated SLR-Induced Groundwater Rise in Coastal New Hampshire

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Modeling Groundwater Rise with SLR

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Groundwater (GW) model:

  • Existing 3D model

(Mack, 2009) - modified for this study

  • USGS MODFLOW
  • Ran in steady

state – no seasonal effects

  • Grid – 200 ft. x

200 ft.

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Sea Level Rise - Scenarios

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Sea-Level Rise (SLR) High Emissions Scenario:

  • 1.0 ft. SLR (Y: 2030)
  • 2.7 ft. SLR (Y: 2060)
  • 5.2 ft. SLR (Y: 2090)
  • 6.6 ft. SLR (Y: 2100)

From: NOAA (Parris et al., 2012)

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Model Results: Groundwater-Rise Zone (GWRZ)

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Groundwater rise

(% of sea-level rise):

  • GW Rise: 4–5 km

inland

  • Tidal surface-water

flooding: 1.5 km inland

  • GW Rise is reduced

near streams

  • Affected by:
  • geology
  • coastal

geometry

  • GW pumping
  • Can result in

GWI of the land surface

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Potential Impacts from SLR-Induced Groundwater Rise in Coastal New Hampshire

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Will drinking water supplies in the seacoast region be harmed by saltwater intrusion?

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Area where GW is predicted to rise the most with SLR Areas potentially at risk from saltwater intrusion

Red: Overburden wells Grey: Bedrock wells

Areas potentially at risk from saltwater intrusion

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Where might rising groundwater impact marine and freshwater wetlands?

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City of Portsmouth: Approximately 9 km2 (21%) is occupied by freshwater wetlands. The depth of water in wetlands may increase – wetland type transition Freshwater wetland area will increase:

  • 3% by 2030;
  • 10% by mid-century;
  • 19 to 25% by the end
  • f century.
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Where might rising groundwater contact contaminated soils?

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The red triangles are/were active remediation sites

Depth to GW with 6.6’ (2.0 m) of SLR Pease Tradeport, Portsmouth, NH

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Which pavements may fail prematurely due to rising groundwater?

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Roads in the zone of groundwater rise where groundwater is already close to the ground surface will be the most vulnerable.

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Vulnerable sections of roadway

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Vulnerable Roads –

Roads within the GWRZ with GW less than 1.5 m below the road surface.

  • 1022 km of roads are in

the study area

  • 783 km of roads (77% of

the region’s roads) are in the GWRZ.

  • 235 km of the region’s

roads (23%) are vulnerable or 30% of the roads in the GWRZ.

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What happens when the underlying, supporting soils become saturated?

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Fatigue cracking

Pavement life decreases when GW moves into the underlying layers and increased temperature weakens the AC

Rutting

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Pavement evaluation

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Pavement evaluation sites

  • Spaulding turnpike (Divided

highway)

  • Gosling Road (Local road)
  • Route 101 (Statewide

corridor)

  • Route 286 (Regional corridor)
  • Middle St. (Local road)
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Spaulding Turnpike and Gosling Road

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Spaulding Turnpike (divided highway)

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Road surface elevation = 64.9 feet (NAVD88)

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Gosling Road – Pavement profile and analysis

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Road surface elevation = 49 feet (NAVD88)

Road is flooded

Fatigue cracking controls pavement failure

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What can we do?

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There are many options – we have some time . . .

1. Adopting adaptation actions now may save money in increased maintenance, emergency repairs, and environmental harm.

  • 2. Ensuring that our natural systems remain healthy will enable them to

continue performing essential protective functions.

  • 3. Where infrastructure adaptation is extremely costly, a wait and see

approach may be best.

  • 4. Staged adaptation planning: what you do now can influence or constrain

future options.

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Example Adaptation Strategies – Local Road (Gosling Road)

Pavement Life (Nfn/Nfe) Adaptation Costs ($/yd2) Pavement Options

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Concluding Remarks

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SLR, Rising GW, and Coastal NH Summary

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1. The Groundwater Rise Zone (GWRZ) caused by sea-level rise was identified in coastal NH with a regional groundwater-flow model.

  • 2. Vulnerable assets, within the GWRZ, are those where groundwater is

already close to the base of the structure, i.e. within the range of projected groundwater rise.

  • 3. Detailed asset-specific vulnerability studies are required to account for

local conditions and to assess the asset’s resiliency to groundwater and temperature rise from climate change.

  • 4. Adoption of adaptation strategies now will avoid expensive emergency

repairs, groundwater contamination, and harm to natural resources.

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Acknowledgements

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  • Co-authors and advisors:
  • Jennifer Jacobs, Ph.D., University of New Hampshire
  • Jo Sias Daniel, Ph.D., University of New Hampshire
  • Paul Kirshen, Ph.D., University of Massachusetts Boston
  • Advisors: David Burdick, Ph.D., University of New Hampshire; Eshan Dave,

Ph.D., University of New Hampshire

  • New Hampshire Sea Grant for funding this work
  • UNH Center for Infrastructure Resilience to Climate (UCIRC)
  • The Infrastructure and Climate Network (ICNet)
  • NH Department of Transportation (NHDOT)
  • NH Department of Environmental Services (NHDES)
  • NH Seacoast Transportation Climate Working Group (NHS TCWG)
  • NH Coastal Adaptation Workgroup (NHCAW)
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Thank you for your interest. Questions?

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Jayne F. Knott and Jennifer M. Jacobs University of New Hampshire e-mails: jfk1011@wildcats.unh.edu Jennifer.Jacobs@unh.edu

Source: www.huffingtonpost.com

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Route 286 (regional corridor)

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Route 286 - Pavement profile and analysis

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Road surface elevation = 13.9 feet (NAVD88)

Road is flooded

Rutting controls pavement failure

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Adaptation Strategies – Regional Corridor (Rte. 286)

Pavement Options Adaptation Costs ($/yd2) Pavement Life (Nfn/Nfe)