SEA LEVEL RISE : Impacts on RichmondKristina Hill, PhD | UC Berkeley | [email protected] ROTTERDAM, NETHERLANDS –Water Plan 2.0 (2009)
State of California Sea level Rise Guidance (OPC, 2018) 3 feet
6.7 feet
10.2 feet
ScarySuper scary
State of California Sea level Rise Guidance (OPC, 2018) 3 feet
6.7 feet
10.2 feetPermanent,high valueinvestments
Temporary,low valueinvestments
State of California Sea level Rise Guidance (OPC, 2018) 3 feet
6.7 feet
10.2 feetPermanent,high valueinvestments
Temporary,low valueinvestments
By 2040, 0.5 to 1.8 feetBy 2050, 1 to 2.5 feet
What’s new in sea level rise research?
“Icefin” robot probe, dropped through a drilled hole in the ice at Thwaites Glacier in 2021.
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2023 California State Guidance on sea level rise?
Mixed news about sea level rise:•In the next 30 years, sea level could rise as much as it did in the last 100 years (that’s only about 1 foot, so it’s good news)•Between 2050 and 2100, sea level could still rise very quickly to a worst-case level of 6 -10 feet, because observations from Antarctica are very worrying (cracks above and below a key glacier, lowest-ever sea ice levels in 2022-23)•We’ll know a lot more by 2030, if not sooner Where is Richmond most vulnerable to permanently higher tides and storms? 1874 map shows the extent of tidal marshes and mud flats in what is now Richmond Point Isabel
Harbor Channel andMarina Bay
At some future point, Richmond will see 9 feet of sea level rise. (BCDC Bay Area Flood Viewer) BCDC and Cal EPA know that Richmond has a legacy of contaminated soil, and that sea level rise will create new health hazards.Soil Contamination
Example: Sea level rise alone at the Liquid Gold Superfund site Example: Sea level rise alone at the Liquid Gold Superfund site Example: Sea level rise alone at the Liquid Gold Superfund site Example: Sea level rise alone at the Liquid Gold Superfund site ROTTERDAM, NETHERLANDS –Water Plan 2.0 (2009)
What is “shallow groundwater”?
SALTWATER
FRESHWATER
Groundwater comes from two directions –from rain on land, and from the ocean. The fresh groundwater floats on top of the saltwater, even underground, because it’s lighter. Tides can raise the groundwater near the shore, but groundwater moves more slowly because of friction with the soil.
Saturated zone (Groundwater)
Unsaturated zone
Pore spaces in soil
“the water table”
Shallow groundwaterThe “water table” refers to the shallowest layer of that water, which often lies just below the surface of the soil.
Source: American Public Works Association
Groundwater infiltration into a storm or sanitary sewer pipe TODAYShallow groundwater sits on top of salty groundwater, which is like the “toe” of the ocean poking into the land underground. 1 Foot of sea level / groundwater riseRising groundwater can enter sewer pipes and create higher flows in creeks –even if a levee was built at the shoreline. Shallow water under roads increases maintenance costs by reducing pavement durability. 2 Feet of sea level / groundwater riseGroundwater can come up into contaminated soils, causing the contaminants to move on or in the groundwater . It can even change directions of flow. 3+ Feet of groundwater riseEventually flooding emerges at the surface, but by then, most of the impacts have already occurred that will affect land value.
January 2021 King Tide, San Leandro
Where is Richmond most vulnerableto rising groundwater?
Old riverbeds –shown here in dark pink -run under Richmond like fingers on a hand that extends from the hills to the Bay.Gravels in those old riverbeds allow groundwater to flow through faster, which can make the water table higher where the “fingers” meet the urban fill at the shoreline.That’s why land parcels at the end of the fingers are more vulnerable to rising groundwater, with those higher groundwater flows coming down from the hills.
Contamination in soilCan move around when groundwaterrises into it from below Street addresses of contaminated sites over shallow, rising groundwater (0 to 6.6 feet deep today) Hill and Lindquist 2023Richmond has a lot of parcels with old contaminationin the soil, sitting on top of shallow groundwater (in blue).
South shoreline case study(UC Berkeley, 2020-2023)Changing groundwater levels can change the flow directions of contaminants underground LIQUID GOLD SUPERFUND SITE:Low resolution USGSgroundwater map
PROJECTING FLOWDIRECTIONS FORCONTAMINANTS UNDERGROUND
LIQUID GOLD SUPERFUND SITEHigh resolution DTSCgroundwater map,in a dry year (2009)
PROJECTING FLOWDIRECTIONS FORCONTAMINANTS UNDERGROUND
PROJECTING FLOWDIRECTIONS FORCONTAMINANTS UNDERGROUND
LIQUID GOLD SUPERFUND SITEHigh resolution DTSCgroundwater map,in a wet year (2008) Flow directions projected frommonitoring wells, using low-resolutionUSGS groundwater contours (2020) Flow directions projected frommonitoring wells using high-resolutionDTSC groundwater contours (2019)
Liquefaction Extreme shaking in an earthquake can beworsened by high groundwater in artificial fill soilsSafe building foundations are more expensive where the risk of liquefaction is higher.
Richmond, CASoils prone to extremeshaking in an earthquake.Rising groundwater canexacerbate this problem.USGS (2006) Impacts on Richmond from a rising sea level and rising shallow groundwater:1.Underground pipes will be compromised (infiltration causes problems with storm sewers and sanitary sewers, which require more maintenance)2.Increases risks of extreme earthquake shaking (liquefaction) on fill and former wetland soils3.Increases probability of tidal inundation at contaminated sites4.Increases likelihood that contamination underground will move towards sewer lines, potentially affecting people in buildings, as well as towards the Bay5.As groundwater becomes more saline, the risk of foundation failures increases 6.Pavements will degrade faster over shallow groundwater, requiring more maintenance7.Eventually, the risk of flooding at the surface increases. Levees or cut-off walls can increase the rate at which groundwater rises on the landward side. Pumping can increase the rate at which the land sinks, which happened in New Orleans.
In summary, there are major risks to human health, the environment, infrastructure… and to the property tax base for coastal cities,as well as to a city’s bond rating.
Debt repayment period
Useful life of the asset
Years. 51015202530
= Lost adaptationcapacity
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Question: How to protect safety, support quality of life and conserve the value of public/private assets as these now unavoidable changes occur? Step 1: Start comparing the functional period of new infrastructure investments to their repayment period –this is critical, to avoid being stuck with useless debt.Step 2: Make an Adaptation Plan: identify adaptation pathways for adding new development in the safest locations while transitioning away from conventional development in dangerous areas (consider Dutch-style housing precedents)Step 3: Prepare for groundwater to rise at contaminated sites
PLANBUILDUSE
Effective adaptation takes time, and the right time to start is now.
PLANBUILDUSE
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