SEA LEVEL RISE DEFINITIONS
CRISSY FIELD SEA LEVEL RISE ADAPTATION TOOLS
MEAN HIGHER HIGH WATER (MHHW) =
SEA LEVEL RISE PREDICTION CURVES =
The average of the higher high water height of each tidal day observed over the standard 19 year observation period.
Prediction curves are based on a new set of scenarios that replace the Special Report on Emissions Scenarios (SRES) standards employed in two previous reports. The new scenarios are called Representative Concentration Pathways (RCPs). The following chart represents two pathways : RCP8/5 and RCP2.6 (the numbers refer to forcings for each). RCP2.6 and RCP8.5 are compilations of the mean of all study respondants. Line data reprsent NOAA’s high, middle high, middle low, and low sea level rise assessments (Parris et al., 2012).
KING TIDE = A colloquial term for an especially high tide above a certain elevation. It refers to a combined effect of lunar and solar alignment on the same side of earth, including other effects such as storms. In the context of Crissy Field, once a tide surpasses Elevation 7, it is considered a King Tide.
RETREAT
Allow water levels to rise. Abandon and deconstruct parklands, buildings, utilities and roads before they eventually flood.
REEF
Wave attenuation is achieved through beaches and off-shore artificial reefs before waves reach shore. Beaches act as sand engines. Off-shore reefs have the added benefit of oyster habitat. Useful in conjunction with other SLR adaptation.
RIPRAP
Loose stone used to armor vulnerable shorelines and protect shorelines from erosion or scour.
BEACH
Beach nourishment is importing or pumping sand from elsewhere onto an eroding shoreline to maintain a beach.
DUNE
Hill of sand near a beach on shorelines. Dunes form by interaction with the flow of air or water. Dune habitats provide a recess for highly specialized plants and animals including rare species and endangered species.
WETLAND
Wetlands play a number of roles in the environment such as water purification, flood control, carbon sink and shoreline stability. Wetlands are considered a “Living Shoreline” ecosystem in which a wide range of plants and animals can prosper.
WALKWAY
Elevated or floating walkways allow visitors to experience the park while it is underwater Pilings and footings are required for elevated walkways. Floating walkways are successful in protected waters only.
Vertical wall holds water back. It can fit in narrow horizontal spaces. Seawall can be retaining wall or free-standing. Seawalls can cut off waterfront views.
LEVEE
Linear earthen berm protection. Levees are the most traditional flood protection strategy. They are less expensive than most solutions but they require medium horizontal distance and significant maintenance.
100YR TIDE EVENT = A flood height that statistically has a 1-percent chance of occurring in any given year.
WAVE RUN UP =
ELEVATED OR FLOATING
Wave runup is the maximum vertical extent of wave uprush on a beach or structure above the still water level. Wave runup is an important process in causing and or promoting bluff erosion.
TIDAL CHARTS = CRISSY FIELD TIDE CHART - JAN 30, 2016 Changing every 6 hours, there are 2 high tides and 2 low tides every day. One high tide is higher than the other, called Higher High Water (HHW). And one low tide is lower than the other, called Lower Low Water (LLW). A region’s average of these daily tidal extremes are called Mean Higher High Water (MHWW) and Mean Lower Low Water (MLLW). TIDAL DAY HHW
HW
LW LLW
INTERGOVERNMENTAL PANEL ON CLIMATE CHANGE (IPCC) = IPCC assesses the scientific, technical, and socio-economic information relevant for the understanding of the risk of human-induced climate change. It does not conduct its own research or monitor climate related data. The IPCC is international and based in Geneva, Switzerland.
NATIONAL RESEARCH COUNCIL (NRC) = The NRC strives to “improve government decision making and public policy, [and] increase public understanding... in matters involving science, engineering, technology, and health.” (www.nationalacademies.org/nrc/) The NRC is national and based in Washington DC.
INTERTIDAL ZONE = NORTH AMERICAN VERTICAL DATUM OF 1988 (NAVD88) = The official vertical datum for the United States. It consists of a leveling network on North America and is used as a datum for this project’s current and projected elevations.
CRISSY FIELD SEA LEVEL RISE BASICS
SEAWALL
ADAPTABLE Floating, elevated, or first floor floodable buildings. Typically BUILDINGS a short term solution, not always resilient to extreme wind and waves.
DUCKBILL FLAPS
An attachment for pipes and water utilities that allow water to exit the system but prevent high tide water from entering the pipes.
Pump Stations are facilities that use electric pumps and PUMP STATIONS mechanical equipment to drain low-lying land from high waters. Flood-control pump stations are generally located on levees.
Defined as the area that is above water at low tide and under water at high tide. There are many planting and animal habitats located at the Crissy Marsh that require these fluctuating water levels to thrive. At the Crissy Marsh, the intertidal zone ranges from Elevation 4.5-8.0 (NAVD 88).
SUBTIDAL ZONE = Defined as the area that is submerged the majority of the time. It is occasionally exposed during extreme low tides. At the Crissy Marsh, the subtidal zone includes habitat lower than Elevation 4.5 (NAVD88).
CRISSY FIELD SEA LEVEL RISE CALIFORNIA STATE COASTAL CONSERVANCY CLIMATE READY GRANT COMMUNITY STAKEHOLDER MEETING JANUARY 30, 2016