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Concurrent Sessions - Session A

Past, Present, and Future Climate-Related Trends and Maine’s Freshwater, Estuarine, and Coastal Resources

Some PowerPoint presentations are available for download. Please click on session presentation titles below to access the download link.

Session Chairs:

Glenn Hodgkins and Robert Dudley
U.S. Geological Survey, New England Water Science Center


How is climate change affecting – or projected to affect – Maine’s freshwater, estuarine, and coastal resources and what new tools, methods, and data are available to help analyze changes? This session will cover hydrologic and ecological studies of climate-related patterns, trends, and projections for Maine, or regional studies that include Maine.

Session Presentations:


Synoptic Climatology and Generating Mechanisms of Annual Floods in New England and Atlantic Canada
PowerPoint presentation available for download.

Mathias J. Collins1, Johnathan P. Kirk2, Joshua Pettit3, Arthur T. DeGaetano4, M. Sam McCown5, Thomas C. Peterson5, Tiffany N. Means6, and Xuebin Zhang7

  1. National Marine Fisheries Service, National Oceanic and Atmospheric Administration,
  2. Department of Geography, Kent State University, Kent, Ohio
  3. Department of Atmospheric and Oceanic Sciences, University of Colorado at Boulder, Boulder, CO
  4. Department of Earth and Atmospheric Sciences, Cornell University, Ithaca, New York
  5. National Climatic Data Center, National Oceanic and Atmospheric Administration, Asheville, North Carolina
  6. The Baldwin Group, Inc., Asheville, NC
  7. Climate Research Division, Environment Canada, Toronto, Ontario

New England and Atlantic Canada are characterized by mixed flood regimes that reflect different storm types, antecedent land surface conditions, and flood seasonality.  Mixed flood regimes can complicate flood risk analyses, yet the synoptic climatology and precipitation mechanisms that generate annual floods in this region have not been described in detail. We analyze long-term annual flood records at climate-sensitive stream gauges across the region and classify the synoptic climatology of each annual flood, quantitatively describe the precipitation mechanisms, and characterize flood seasonality. We find that annual floods here are primarily generated by Great Lakes-sourced storms and Coastal lows, known locally as “nor’easters”.  Great Lakes storms tend to produce lower-magnitude annual floods (75th percentile).  Tropical cyclones account for few of all annual floods, including extreme events, despite causing some of the region’s largest and most destructive floods.  Late winter-early spring is when the greatest number of annual floods occurs region-wide, and rainfall is the dominant flood-producing mechanism. Rainfall in combination with snowmelt is also important.  Both mechanisms are expected to be impacted by projected regional climate change. We find little evidence for associations between flood-producing synoptic storm types or precipitation mechanisms and large-scale atmospheric circulation indices or time periods, despite increases in annual flood magnitudes in New England in recent decades. To better investigate such associations, flood series that include more floods than just the largest of each year, and their associated synoptic climatologies and precipitation mechanisms, should be analyzed.

Vulnerability of Water Conveyance Infrastructure Due to Changing Landscape within the Context of a Changing Climate

Michael Simpson1, Latham Stack2, Trisha Moore3, Robert Roseen4, James Gruber5

  1. Antioch University New England, Environmental Studies Dept., Keene, NH;
  2. Syntectic International, LLC, 4112 SW Coronado St., Portland, OR
  3. University of Minnesota, St Anthony Falls Laboratory, Minneapolis, MN
  4. University of New Hampshire, Durham, NH
  5. Antioch University New England, Environmental Studies Dept., Keene, NH

 Results will be presented from NOAA and US EPA funded research from 2007 thru 2013, in the context of rural, the peri-urban and urban watersheds in New England and the upper Midwest. This research examined the hydrologic impact of climate change and land use scenarios on existing water conveyance infrastructure.

The built infrastructure in the watersheds were assessed and mapped with a standardized protocol. Field and spatial data is then utilized to create a nested GIS model that calculates current and projected runoff volumes for the 24-hour precipitation events. Based on current zoning ordinance regulations, multiple build-out analyses were developed for the study watersheds.

These build-out scenarios were combined with estimated, mid-21st century storm magnitudes based upon downscaled global greenhouse gas emission scenarios. Once vulnerable infrastructure was identified, a marginal cost analysis was completed for alternative actions of response.

The technical outputs of these studies informed concurrent community resilience building processes that increased stakeholder capacity at the local level in adapting to change. The studies’ approach demonstrates the implementation of a quantified, local-scale, and actionable protocol for maintaining historical risk levels for communities facing significant impacts from climate change and population growth.

Using GIS to bring Superstorm Sandy to Maine: Updating Maine’s Hurricane Surge Maps
PowerPoint presentation available for download.

Rachael E., Dye1, Peter A. Slovinsky1Christian H. Halsted1, Joseph Young2

  1. Maine Geological Survey, Department of Agriculture, Conservation and Forestry, Augusta, ME;;
  2. Maine Geolibrary,51 Commerce Drive, Augusta, ME

In 2006, the US Army Corps of Engineers created hurricane surge maps for the Maine coastline to aid emergency management planning efforts.  This dataset was created using outputs from the National Hurricane Center’s Sea, Lake, and Overland Surges from Hurricanes (SLOSH) model along with best-available topographic data, which at the time, had a 10-m cell size and an approximate vertical accuracy of 2.44 m RMSE.  Since then, the SLOSH model basin was updated by the NHC to provide higher resolution grids of potential storm surge heights associated with landfalling hurricanes.  The entire Maine coastline has also been mapped using Light Detection and Ranging (LiDAR) in a series of flights, and a bare earth digital elevation model (DEM) with 2-m cell size and a vertical accuracy of 0.15m RMSE created.  The Maine Geological Survey, in partnership with the Floodplain Management Office and funding from the Federal Emergency Management Agency, used these datasets to create updated hurricane surge maps for Category 1 and 2 hurricanes making landfall at mean and mean high tide.  An ArcGIS 10.1 script tool was created to analyze the data and create output GIS layers.  Outputs include the spatial extent of inundation, SLOSH model error bands, and potential inundation depths.  These datasets are being shared with the emergency management planning communities at the local, regional, and state levels to help prepare for the “what if” scenario of a hurricane landfall in Maine.

Are Maine marshes losing area with accelerated sea-level rise?

*Please contact Kristin Wilson for a copy of the PowerPoint presentation.

Kristin R. Wilson1, Joseph T. Kelley2, Daniel F. Belknap3

  1. Wells National Estuarine Research Reserve, Wells, ME;
  2. School of Earth and Climate Sciences, University of Maine, Orono, ME
  3. School of Earth and Climate Sciences, University of Maine, Orono, ME

Coastal wetlands are vulnerable to climate change, most directly through losses related to sea-level rise.  Recent estimates predict an acceleration in this sea-level rise-associated loss during the current century, with 20-45% of tidal wetlands converting to open water.  Previous work notes ponding as a precursor to marsh loss and that loss patterns are spatially explicit.  Despite this, studies have been geographically concentrated in mostly three areas:  Gulf Coast, Chesapeake Bay, and Venice Lagoon.  This study combines field ecophysical surveys, multivariate analyses, and photographic time-series analyses to characterize 421 pools from five salt marshes to describe patterns of surficial marsh change in Maine.  Study results reveal four pool clusters, with subsurface morphology being the greatest driver of differences between pool types.  Analyses of aerial photographs reveal slight to moderate increases in the amount of total pool area in all salt marshes, mostly through the addition of small pools and through the growth of large pools in interior marsh sections and along the upland marsh border.  Analyses of individual pool changes indicate that pools are highly dynamic over decadal time periods.  Overall, Maine marshes do not appear to be transitioning to open-water states over the rapid time-scales observed in other areas; rather, they appear to be in a state of dynamic equilibrium, which includes generation, evolution and revegetation of pools.

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