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Marin Sea Level Rise Viewer

Background information

Zoomed out view of all of Marin County. A key in the lower left corner of the image lists datasets available in the viewer.The Marin Sea level Rise Viewer -- available at marinmap.org -- is a new, public facing interactive viewer that uses consistent countywide datasets to provide a hyper-local look at potential future shoreline flooding in Marin. This viewer allows users to zoom in and out and see curated datasets in relation to Marin County’s sea level rise risk. (Instructions on how to use the Sea Level Rise Viewer can be found further down the page.)

Commissioned by a group of local electeds and staff leadership from Marin’s cities and towns, the viewer was developed by County staff. It is hosted by MarinMap, a consortium of local governments, special districts and other public agencies that have joined together to create a Geographic Information System (GIS) that provides common datasets and applications across Marin County.

Sea level rise scenarios

The Marin Sea level Rise Viewer allows one to explore possible near term, mid-term, and long-term future sea level rise impacts anywhere in Marin County. The viewer provides three scenarios of sea level rise alone and three scenarios that add in a 100-year storm surge event. Storm surge happens when atmospheric pressure changes and winds associated with a storm cause water levels to temporarily rise along shorelines. A “100-year storm surge event” means a storm surge with a 1% chance of occurring in any given year.

Near-term

  • 10 inches (0.8 ft)
  • 10 inches with 100-yr storm surge (3.8 ft)

Mid-term

  • 20 inches (1.6 ft)
  • 20 inches with 100-yr storm surge (4.7 ft)

Long-term

  • 60 inches (5 ft)
  • 60 inches with 100-yr storm surge (8 ft)

Sea level rise scenarios provided in the viewer are the same as those used in the 2017 BayWAVE Vulnerability Assessment. They remain consistent with best available science and current state planning guidance.

Data layers available in the viewer

The Marin Sea Level Rise Viewer allows users to easily integrate the sea level rise scenarios listed above with other publicly available data layers. These data layers include:

Political and geographic features

  • City – polygon: cities and towns jurisdictional boundaries in polygon format.
  • City – line: cities and towns jurisdictional boundaries in line format.
  • FEMA 100-yr flood plain: areas currently with a 1% annual chance of flooding according to approved FEMA floodmaps, which do not account for climate change or sea level rise. Parcels within this area are subject to flood insurance requirements.
  • Streams: perennial creeks that flow all year; intermittent creeks that are dry several months a year; and ephemeral creeks that flow only during and shortly after rain events—all from USGS National Hydrology Dataset.
  • Marin County Land Boundary: the current-day land edge, not the legal County boundary, to help visualize shoreline retreat under different sea level rise scenarios.

Local assets & critical infrastructure

  • Building footprints: aerial view of structures’ outline
  • Parcels: publicly available information on address, jurisdiction, zip code, and parcel use type (residential single family, single family attached, multi-family; commercial; industrial).
  • Housing and Job Centers: based on parcel data, this data layer is a proxy for land use, housing, and job locations to show how and where these different parcel types may be affected by sea level rise.
  • Stormwater pump stations: designed to collect runoff from streets and then pump into creeks and the bay. If coast and bay waters are higher than the pipe outfalls, water could backflow from the bay to the streets.
  • Sanitary treatment plants: generally located near the bay and therefore threatened by sea level rise.
  • Fire stations: critical sites for emergency response access.
  • Sea Level Rise Projects: this data layer prepared by County staff includes both climate adaptation and mitigation projects.

Basemaps

  • Aerial Photography
  • Topography
  • Hillshade

How to use the viewer

The Marin Sea Level Rise Viewer is a dynamic, scale dependent mapping tool. When you open the viewer, the map is zoomed out to the full extent of Marin County. Use your mouse wheel or the map’s + - icons to zoom in to your area of interest. You can also click and “drag” on the screen to move the map.

All of the viewer’s data layers are shown in a menu on the left side of your screen.

  • An open eye icon means that data layer is turned on and visible.
  • An eye icon with a slash means that data layer is turned off and is not visible.

Click on an eye icon to turn a data layer on and off. You can have on as many or as few data layers at one time as you choose. Some layers are bigger than others and may take some time to load.

An arrow next to an eye icon means there is a drop-down menu of options for that data layer. Click on an arrow to open a drop-down menu of options and select those of interest.

Greyed out data layers in your menu are not visible at the map extent you are currently viewing. Zoom in on your area of interest until those data layers turn on (in the legend, the data layer names will switch from grey to black).

Click on items of interest on the map to see pop-up windows with additional information. This works for large polygons like a flooded shoreline area as well as small local features like a parcel outline. Note that there may be several layers of data; in that case, you can click through the pop-up panels to get information on each layer.

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