Trail Closure

At Kirby Park, the accessible trail remains closed due to storm damage.

Empire gunclub
Mapping, Geographical Ecology and GIS

Mapping, Geographical Ecology and GIS

Maps have come a long way. Historic maps of the Slough were drawn by hand. They provide a rare snapshot into the Slough’s past and how humans have altered the landscape over time.

Geographic information systems or GIS emerged in the 1970 and 80s. GIS changed forever the way maps were created and analyzed. GIS is a tool that manages, analyzes, and models data from our environment so that we can make decisions based on that information to better study changes over time, conserve and restore important resources, and protect biodiversity into the future.

Find out more about Historical Ecology Tools utilized by our Stewardship Programs.

Past, Present, and Future

Empire Gun Club
Geographic Information Systems technology is helping ESNERR understand the ecological history of the Slough. California’s coastal wetlands have undergone dramatic hydrologic modifications and land use changes over the years. At Elkhorn Slough, marshlands were diked and drained and converted to agriculture. In 1947, an artificial opening to the Monterey Bay was constructed that exposed the Slough to increased tidal exchange.

By digitizing, rectifying, assembling, and analyzing a chronological sequence of historical maps and aerial photographs, we are beginning to quantify patterns of change to the Slough’s wetland habitats and correlate them with historic events.

A specific focus of this research program is to measure rates of tidal erosion, changes in tidal creek morphology, and loss of vegetated salt marsh. We hope to determine whether these trends are accelerating or – hopefully – approaching a new equilibrium.

GIS helps us understand not only Elkhorn Slough’s past, but also its present. Using the combination of sophisticated digital image analysis and old-fashioned (GPS-assisted) field survey work, we produce highly accurate habitat and vegetation maps and perform landscape and connectivity analysis.

Accurate maps of present conditions and an understanding of historic changes are powerful tools for informed stewardship and conservation. Perhaps the most important role for our GIS-based research is for the future: building an accurate baseline to monitor future habitat changes and to guide restoration.

The map below is an example of the work our mapping team and partners can accomplish using the methods described.  This Elkhorn Slough watershed enhanced lifeform and tidal wetland alliance level map is a 33-class land use and land cover and alliance level tidal wetland map of Elkhorn Slough Watershed reflecting the state of the watershed in summer, 2018.  You can visit the interactive map or download the GIS files for this map in the table below.

Elkhorn Slough Watershed Upland Enhanced Lifeform and Alliance Level Tidal Wetlands Map (click map to go to interactive map)

Spatial Data

The Elkhorn Slough NERR, in cooperation with the Elkhorn Slough Foundation, maintains an extensive library of digital aerial imagery of the Slough’s wetlands and adjoining upland areas dating from the 1930s through to the present. The California Department of Fish and Wildlife augments the collection with aerial surveys flown every spring and fall.

The Reserve is also assembling a collection of historic and contemporary maps and a variety of other types of raster and vector spatial data including elevation models and vegetation, land use, and soils coverages.

Download ArcGIS Shapefiles
Click below to download shapefiles covering the Elkhorn Slough watershed that can be viewed and manipulated using ESRI’s ArcGIS software.  The files are in the following coordinate system:  UTM Zone 10 WGS84.

If you do not use ArcView, ArcGIS, or Arc/Info, you can obtain ESRI’s ArcGIS Explorer Desktop program to view and query data layers. Although you cannot add or modify graphics or tables, you can perform many of the viewing functions that ArcView allows you to do. ArcGIS Explorer can be downloaded for free from www.esri.com.

File Description
Click here to get files.
Updated: 11/3/2020
The Elkhorn Slough watershed enhanced lifeform and tidal wetland alliance level map is a 33-class land use and land cover and alliance level tidal wetland map of Elkhorn Slough Watershed reflecting the state of the watershed in summer, 2018. Go to interactive map.
ELK_Habitats_2009.zip
15.7 MB
2009 Semi-automated habitat classification for Elkhorn Slough.  Habitat classes are distinguished according to the theme table field “CODE_DESC”.
vegetation.zip
2.15 MB
2002 Habitat classification for the Elkhorn Slough watershed. Habitat classes are distinguished according to the theme table field “Class”.
water.zip
55 K
Open water, including Monterey Bay, the Elkhorn Slough main channel, and the Moro Cojo Slough channel.
wetland.zip
239 K
Outline of Elkhorn Slough’s tidal wetlands.
streams.zip
40 K
Streams in the Elkhorn Slough watershed.
watersheds.zip
60 K
Boundary of the Elkhorn Slough watershed and its sub-watersheds.
protected.zip
79 K
The Elkhorn Slough watershed’s protected lands. Ownership is specified in the “Protected” theme table field.
roads.zip
63 K
Roads in the Elkhorn Slough region. Roads can be labeled with names in the “Name” field.
cz.zip
28 K
The coastal zone boundary in the vicinity of Elkhorn Slough.

Blue heron in grass

Photo by: Michael McGreevy

Elkhorn Connects Us

Much of our work at the Elkhorn Slough Reserve is powered by volunteers.

Volunteer With Us
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