Data Guide to Climate Change Impact Area Map Layers

This guide presents a brief description of each Climate Change Impact Area map layer and describes how to use this information to identify areas within the state that are most vulnerable to climate change impacts.

Maryland Climate Change Impact Areas

Changes in Maryland’s climate system will likely have far-reaching impacts, most notably those associated with rising sea level, temperature increase and changes in precipitation patterns. Acknowledging the increasing likelihood and magnitude of these impacts and their associated risks is necessary to protect both natural and man-made environments for years to come. The areas listed below represent land areas in Maryland that are projected to be the most sensitive to anticipated changes in climate.

Sea Level Rise Vulnerable Areas

Description: Land areas between 0-2 and 2-5 feet above mean sea level are particularly sensitive to rising sea level over the next 100 years. Maryland has experienced more than a foot of sea level rise in the last century due to the combined forces of regional land subsidence and global sea level rise. Current projections from the Maryland Climate Change Commission predict between 2.7 and 3.4 feet of additional sea level rise by 2100. Sea level rise affects coastal areas by exacerbating coastal flooding, influencing shoreline erosion, and submerging tidal wetlands and other low-lying lands.

Data source: The Sea Level Rise Vulnerability data is a basic bathtub simulation based on elevation data that displays potential inundation at 0-2’, 2-5’ and 5-10’ of sea level rise. The inundation breakouts roughly correlate to Maryland’s projected inundation rates for years 2050 (0-2’) and 2100 (2-5’). The dataset is a derivative of high-resolution topographic data LiDAR (Light Detection And Ranging). The resolution of Maryland’s LiDAR is in 2-foot contours, which provides us with an estimate of future vulnerable resources. Metadata can be downloaded at the DNR GIS data site:

For more information on sea level rise vulnerable areas in Maryland, visit the Coastal Atlas at: 

Storm Surge Risk Areas

Description: Storm surge is the rapid rise of sea level associated with tropical storms. During extreme precipitation events, coastal areas are at an elevated risk of flooding from storm surges that raise the sea much higher than the mean level. Storm surge areas are therefore the coastal locations that are at most risk of experiencing flooding during storms. Changes in global climate patterns and concurrent sea level rise will exacerbate the extent and magnitude of storm surge areas. As mean sea levels rise, storm surge areas will increasingly include more inland areas that may not have been considered vulnerable in the recent past.

Data source: The US Army Corps of Engineers (USACE) completed two hurricane evacuation studies for the eastern (2007) and western (2010) shores of Maryland. The storm surge zones were generated using the Sea, Level, and Overland Surges from Hurricanes (SLOSH) model. SLOSH is a computerized model run by the National Weather Service to estimate storm surge heights resulting from historical, hypothetical, or predicted hurricanes. The model provides geographical displays of color-coded storm surge heights for a particular area based on the shoreline, unique bay and river configurations, water depths, bridges, roads, and other physical features.

For more information on storm surge areas, visit Maryland's Coastal Atlas (

Erosion Vulnerability Areas (EVA)

Description: Erosion vulnerable areas are areas susceptible to shoreline erosion processes along the Maryland portion of the Chesapeake Bay. These areas were identified by analyzing historic shoreline change rates generated by the Maryland Geologic Survey, combined with an inventory of current shoreline conditions to evaluate the potential position of the shoreline in 50 years. Sea level rise and storm surge will increase erosion, accelerating property and wetland loss and sending sediment into the Bay. The map outputs identify where resources will be vulnerable, and can enhance or redirect future development options for individual communities, and define areas where opportunities for conservation easements could be directed.

Data Source: The Baltimore District Army Corps of Engineers and Maryland DNR developed EVA to identify areas alongshore that have demonstrated historic patterns of instability, and currently support valued natural, social, or economic resources. This data layer is for use only as a planning “window” to evaluate potential areas vulnerable to erosion based on historical trends. As a planning tool, EVA uses a planning window to project shoreline position in 50-years to inform local planners where community infrastructure, cultural resources, and habitat are potentially at risk in the future. Note: For all coastal counties except Worcester use Maryland's Coastal Atlas – Erosion Vulnerability Assessment. For Worcester County, use Maryland's Coastal Atlas: Shorelines Rates of Change, Transect Data (Moderate (4-8 feet/year).

For more information on shore erosion, visit Maryland's Coastal Atlas at:

Wetland Adaptation Areas

Description: As sea level rises, wetlands along the coastline may move landwards in response. Wetland Adaptation Areas area areas likely to be important future wetland habitats and/or that provide migration or transition zones for wetlands to move landward as sea levels rise. New Wetland Areas (Year 2100) are areas that currently exist as undeveloped dry land likely to change to wetlands by the year 2100 as sea level rises.

Data Source: Wetland Adaptation Area data comes from Maryland's Coastal Atlas. The dataset represents a series of priority subsets of wetland adaptation areas that would help to facilitate landward movement of coastal wetlands subject to dislocation by sea level rise. The marsh modeling displayed on this application is intended to be viewed at the landscape level and is based on the Sea Level Affecting Marshes Model (SLAMM) version 6.0.1 that was run by DNR in 2011. The model was run at the county level, for all 16 coastal counties and Baltimore City using local erosion, sedimentation, accretion rates and an estimated 3.4 foot rise in sea level by the year 2100 as outlined in Maryland’s Climate Action Plan.

For more information on coastal habitats and sea level rise and the SLAMM modeling, contact DNR’s Chesapeake and Coastal Program (

100-year and 500-year Floodplain Areas

Description: Floodplains along rivers, streams and within tidal and coastal areas absorb flood waters during large storm events. Increasing precipitation and more intense storm events will saturate the ground and expand the floodplain. In tidal areas, rising sea level will also increase the inland extent of the coastal floodplain over time. The 100 year flood now occurs on a 60 year cycle in our region and the current 100 year flood is expected to occur every 20-50 years by 2100.

Data Source: 100-year Floodplain: The map shows areas of flood hazards corresponding to the 100-year flood. Flood hazard areas on the Flood Insurance Rate Map are identified as a Special Flood Hazard Areas (SFHA) and are defined as the areas that will be inundated by the flood event having a 1-percent chance of being equaled or exceeded in any given year. The 1-percent annual chance flood is also referred to as the base flood or 100-year flood. SFHA’s are labeled as Zones A, AO, AH, A1-30, AE, A99, AR, AR/A1-30, AR/AE, AR/AO, AR/AH, AR/A, VO, V1-30, VE, and V. 500-year Floodplain: The map shows areas of flood hazards corresponding to the 500-year flood, which are areas referred to as Moderate Flood Hazard Areas. Moderate flood hazard areas, labeled Zone B or Zone X (shaded), as shown on a Flood Insurance Rate Maps, are the areas between the limits of the base flood and the 0.2 percent-annual-changes (or 500-year) flood. The areas of minimal flood hazard, which are the areas outside the SFHA and higher than the elevation of the 500-year flood zone, are labeled Zone C or Zone X (shaded).

This data set is contained within Maryland’s OSPREY (Operational Situational Preparedness for Responding to Emergency), Version 1.0 mapping platform, released in August 2011. OSPREY is a simple, easy-to-use, Internet-based map for public use to monitor hazards and emergencies in Maryland. It contains static and real-time data for weather, incidents, traffic, camera and CCTV feeds, and other spatial assets. It consumes and shares data resources with other situational awareness mapping systems within the National Capital Region and with other partners by relying on open standards and other interoperable platforms. For additional information concerning emergency events go to the Maryland Emergency Management Agency web site at

Note: The Maryland Department of Environment, as the State Coordinating Office for the National Flood Insurance Program, is in the process of updating Flood Insurance Rate Maps (FIRMs) throughout Maryland. For more information on the status of tidal and non-tidal flood map modernization program for your jurisdiction, visit: Local jurisdictions should use the most up to date floodplain data available for planning purposes.

Drought Hazard Risk Areas: Water Supply

Description: MDE’s Water Supply Program conducts routine drought assessments for water supply that are based on four indicators: precipitation, stream flows, groundwater levels, and reservoir capacity. Drought susceptibility for a particular water supply depends on a number of factors, including the type of water source and whether storage or backup is available for the water user, in addition to climatic considerations. For example, groundwater wells using confined aquifers are less vulnerable to the water availability fluctuations of drought. Those with large reservoir systems that retain substantial storage for the system, and those that have alternate sources available (such as the City of Baltimore’s use of the Susquehanna River as a backup source) are much more resilient during drought. Those using unconfined aquifers in the coastal plain or fractured rock regions of the State are more likely to experience impacts from drought.

This map indicates generalized areas of vulnerability for community water systems based on the most common features of water systems within the areas. Water systems and/or individual wells may be more or less vulnerable than what is indicated on this map based on the individual characteristics of the system.

In particular, individual wells may be more vulnerable to drought if they are drilled in shallower aquifers, or constructed in such a way that their pumps can no longer draw water when water levels fall. Sometimes individual wells can be impacted by nearby withdrawals (such as agricultural irrigation) that increase significantly during periods of dry weather. In addition to more frequent and longer droughts, water systems are also likely to be impacted by other effects of climate change, including increased flooding, more intense storms, and/or greater water demand.

Data Source: Maryland Department of the Environment’s Water Supply Program.

For more information, visit

Drought Hazard Risk Areas: Agriculture

Description: Rising temperatures and reduced summer rainfall increase the likelihood of water shortages from drought in the summertime, resulting in lower streamflows and groundwater levels and drier soils. About 79% of the state's counties will face higher risks of water shortages by mid-century as the result of climate change. Droughts affect agricultural production, drinking water supplies and fish populations and maintaining water levels in streams and reservoirs are critical for all three, especially in the summer months. Between 1995 and 2010, 75 drought events of varying length and severity were recorded for Maryland in the NOAA National Weather Service, National Climatic Data Center storm database.

Data Source: Maryland State Hazard Mitigation Plan (2011)

For more information, visit

Wildfire Priority Areas

Description: Wildfires are a common occurrence in Maryland. In an average year, the Maryland Forest Service responds to 500 wildfires, which burn more than 4,000 acres of land. Fire departments respond to over 5,000 wildfire incidents per year. While some wildfires in Maryland can burn hundreds or even thousands of acres, most are smaller in size, burning less than 10 acres. Wildfires occur in every month in Maryland, but peak in the spring and fall. During these seasons the leaves are off the deciduous trees, allowing sunlight and wind to reach the forest floor and dry the forest fuels. The relative humidity of the air is also drier and, combined with a breeze, creates the conditions for wildfires to spread rapidly. Maryland may face increased potential for catastrophic wildfires as average annual temperatures increase along with drought potential. This dataset shows where the impact will be most severe.

Data Source: 2005 Maryland DNR Forest Service. This data is based on the Maryland DNR Forest Service Geomatics Lab THARSFE Wildland Urban Interface (WUI) Fire Model. The model is a composite of: wildfire risk based on wildland urban development level, wildfire hazard fuels density and types of ground cover and wildfire sensitivity based on landuse and perceived value. Fire equipment and fire response accessibility were used in the model to show the ability of the local governments to deal with WUI fire. The WUI THARSFE model was broken out originally by 12-digit watersheds and natural breaks of the summed zones model values into five categories ranging from very low to extreme fire impact.

For more information on wildfires in Maryland, contact the Maryland Forest Service at

High Quality Cold Water Resources at Risk

Description: These areas represent habitats of cold water dependent species, such as Brook trout. These species typically cannot survive when water temperatures exceed 68 degrees Fahrenheit. Climate change may exacerbate the effects of anthropogenic alterations to Maryland’s environment, such as forest clearing for development and agricultural production.

Data Source: DNR-Maryland Biological Stream Survey. This dataset identifies the State’s remaining watersheds that still support native fish species dependent on pristine, cold water habitats. Data can be accessed at:

For more information on rivers and streams in Maryland, contact the DNR’s Resource Assessment Service (