NATURAL and CULTURAL FEATURES of MONMOUTH COUNTY

2-3 million years, the Wisconsin, began melting about 21,000 years ago. The resulting
sedimentation from the glacial melt built out a broad sloping plain and a continental shelf for
about 185 miles from the present shoreline (NOAAPB, 2009). About 2500 years ago, sediment
along the shore began accumulating and barrier islands, dunes, bays and other aspects of the
present-day shoreline began to develop (Roberts and Youmans, 1993). Barriers are the dominant
shoreline type along the Atlantic coast, but only comprise 15% of shorelines globally (EPA,
2009). The shaping of the Atlantic coast is due to its sloping landscape, the slow rates of sea
level rise for the past 5000 years, the sufficient sand supply, and relatively minor tectonic
activity (the cliffs that characterize the Pacific coast are due to the more recent collision of
tectonic plates) (EPA, 2009). About 500 years ago the accumulation of sediment along the
Atlantic coast reversed, and sand began to be eroded offshore (Roberts and Youmans, 1993).
If massive amounts of glacial meltwater reduce the salinity of the ocean in the North Atlantic, it
could prevent the northward flowing Gulf Stream from sinking near Greenland and flowing
south along the ocean floor towards Antarctica, shutting down the global network of currents that
sustains climate (WU, 2009). Studies of ocean sediments in the North Atlantic and of ice cores
in Greenland reveal that the Great Ocean Conveyor Belt (also know as thermohaline circulation
and the Meridional Overturning Circulation) has shut down many times in the past, often
coinciding with abrupt climate change (WU, 2009). According to a 2005 report by Princeton
University, sea level rising slowed 6000 years ago; a global-mean sea level rise of .1 to .2
mm/year has been happening in the last 3000 years, and this rate may have doubled since the mid
nineteenth century. Their model predicts that sea levels will rise 2-4 feet by the end of the 21 st
Century, moving the shoreline back 240-480 feet, which will inundate 1-3% of NJ’s land areas,
and periodically flood 6.5-9%. It may increase flooding 3-20 times in the coastal areas located
in the current 100-year flood level of 9.5 ft (2.9 m), and predicts that 100-year floods will occur
every 5 years (Cooper et. al., 2005). For every degree that the ocean warms, sea level rises
about a foot; a three foot rise would jeopardize all bayside property with flooding (Farrell, 2007).
NJ is especially vulnerable to rising sea level due to geologic subsidence (the coastline is sinking
under the weight of accumulating and compacting sediment, due in part to freshwater withdrawal
from coastal aquifers), the topography of its coastline, current coastal erosion, and a high density
of coastal development (EPA, 2009; SNJ, 2008). If the Greenland ice sheet continues to melt at
the rates currently being measured, global sea level rise will increase significantly, and the
severity and frequency of coastal flooding in New Jersey will be even greater (SNJ, 2008).
Fourteen of the twenty largest urban centers in the US are located within 100 km (62 miles) of
the coast with elevations less than 10 m (32.8 ft) above sea level (the 10 m elevation is the
common benchmark to study flooding) (EPA, 2009).
Between 1780 and 1980, thirty nine percent of NJ’s original 6000 km2 of coastal and interior
wetlands, which buffer storm surges along the coast, were lost to human activities; about one
fifth of this happened between 1950 and 1970. The annual rate of loss slowed to 7 km2 between
1986 and 1995 (Cooper et. al., 2005). The additional stormwater volume from impervious
surfaces like asphalt – which produce as much as 16 times more water than undeveloped woods -
increases the probability that two-year, channel forming (bankfull) storms will swell streams
from once every 2 years, to 5 times every 2 years (Snodgrass, 1998). Bankfull storms are used
as design storms for constructing stormwater infrastructure and Best Management Practices such
as detention basins; it is predicted that by the end of this century, as Atlantic City floods, storms
that are now happening once every hundred years will be occurring once every 1-2 years
(UCSUSA, 2008). The present 100-year storm produces a rise of 2.89 meters above National
Geodetic Vertical Datum (NGVD) for the Atlantic coast of New Jersey (Lathrop et al., 2007).