Climate change is mostly attributed to human-produced carbon emissions. Though global energy-related CO2 emissions fell during the pandemic, this turned out to be only temporary. While emissions are now declining in 26 countries, these efforts remain insufficient to counteract the growth in global emissions in China and India. Growth in total CO2 emissions for our planet continued to grow at about 1% per year worldwide for the past decade leading to a continued increase in CO2 in the atmosphere and continued global warming.
The sad truth appears to be that any chance to reduce CO2
emissions enough to prevent climate change is long gone and the changing climate
will impact life on earth. If the ice sheet collapses, even if temperatures are
restored it will take millennia to restore them. Coastal Virginia and other
coastal locations are threatened by rising waters. High rates of land
subsidence, combined with sea level rise, means Virginia is experiencing one of
the highest rates of relative sea level rise in the United States. Virginia has
experienced more than 18 inches of relative sea level rise in the past 100
years. We need to make our communities resilient to the challenges ahead.
The changing climate is bringing more intense hurricanes and
nor’easters, more frequent heavy rainfall events and increased frequency of
tidal flooding from sea level rise are predicted in the changing climate. The Virginia
Coastal Resilience Master Plan contains an analysis of the threat of flooding
in Virginia’s coastal region due to sea level rise and changing precipitation
patterns. It is a long-range plan to guide activities to mitigate severe and
repetitive flooding in Virginia's coastal region. However, what Virginia and
other locations have overlooked is that inland flooding is also a significant threat
that is much harder to forecast. We are
seeing more inland flooding across the southeast and the United States, and we
are unprepared, not just in Virginia.
The relationship between climate change and flooding is
complex. Shoreline flooding is the result of land subsidence, sea level rise,
building in the flood plain and storm surge. The most well-established
connection between climate change and inland flooding is that more warming
leads to more intense rainfall, which in turn increases flood severity in the
inland areas. Land use changes also contribute to flooding.
There have always been great storms, but our changing
climate is increasing storm intensity. Locally (here in Prince William County
Virginia), rainfall averages approximately 44 inches per year, but varies from
year to year. Climate forecasts are for our region to get wetter
with more intense rainstorms and droughts to get more severe. (ICPRB). We have
also changed the land. Increasing impervious cover from roads, pavement and
buildings as our area continues to build out does two things: It reduces the
open area for rain and snow to seep into the ground and causes stormwater
velocity and quantity to increase. Stormwater runoff increases in quantity and
velocity washing away stream banks, flooding roads and buildings carrying
fertilizers, oil and grease, and road salt to our rivers and streams.
Rainfall intensification effect reportedly accounts for about
one-third of all damages from inland flooding in the U.S. in recent
decades. Changes in land use and building in the flood plains for rivers intensify inland flooding and account for most
of the remaining damage. Land use changes that increase impervious cover
reduces the open area for rain and snow to seep into the ground and percolate
into the groundwater to be stored for later. Instead, almost all the storm
water is carried to streams and rivers. The impervious surfaces cause
stormwater velocity to increase preventing water from having enough time to
percolate into the earth, increasing storm flooding.
Increased stormwater volumes and mud flow are a direct
result of clearing the land of trees and vegetation and construction activities
for buildings and roads. The devastating flooding we’ve seen in Texas and North
Carolina’s inland mountain hundreds of miles from any coastline were not expected-
there were no plans for notification, evacuation or response. In both
instances floodwater carried away entire houses, cars and people and washed out
highways, cutting off access and escape routes.
Prince William County has committed to preparing for the
impacts of climate change as part of our goal of becoming a Climate Ready
Region by 2030. In line with this commitment, the county staff has concentrated
on understanding the susceptibility of our county's people and infrastructure
to local climate hazards to meet the community's most pressing needs. The county completed a vulnerability assessment in January
2023. This evaluation was designed to anticipate future conditions that could
amplify existing vulnerabilities.
From 2018 to 2021 Prince William County had 60 reported
Swift Water Rescue events and 178 reported VDOT road closures due to intense
precipitation and flooding. These were mostly inland events. This was
unexpected because the eastern edge of our county is shoreline. Prince William
County realized that they need detailed stormwater modeling to
better understand how flooding occurs throughout the County during
precipitation events and to better understand the limitations of existing
stormwater infrastructure.
In their recent study, Projected changes in extreme
streamflow and inland flooding in the mid-21st century over Northeastern United
States using ensemble WRF-Hydro simulations, Sujan Pal et
al stated “The Northeastern United States (which includes Prince William County
in their study) has experienced …increases in extreme precipitation events over
the past five decades (Melillo
et al., 2014, Walsh
and Coauthors, 2014, Parr
and Wang, 2015a). While the intensities of the most extreme precipitation
events (or the heaviest 1% of all daily events) have increased in every region
of the contiguous United States since the 1950s, the maximum change in precipitation
intensity of extreme events is occurring in the northeast. “
The results of this study indicate an increase in mean
(20–25%) and extreme (>40%) precipitation in near future over the northeast
(including the Potomac River basin). In addition, water depths resulting from
extreme inland flooding may increase more than 100% in some regions.
Neighborhood scale projections that they created suggest that the major cities
of the northeast and the surrounding areas will likely be at higher flood risk.
In turn, extreme precipitation and flooding can pose significant risks to their
infrastructures and networks. It is time to focus on climate adaptation. You
can read the full paper at the link below.
Sujan Pal, Jiali Wang, Jeremy Feinstein, Eugene Yan,
Veerabhadra Rao Kotamarthi, Projected changes in extreme
streamflow and inland flooding in the mid-21st century over Northeastern United
States using ensemble WRF-Hydro simulations, Journal of
Hydrology: Regional Studies, Volume 47, 2023, 101371, ISSN 2214-5818, https://doi.org/10.1016/j.ejrh.2023.101371
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