Land is designated as a wetland if
it is saturated with water for at least part of each year. Wetlands mitigation involves preserving,
restoring, or constructing these areas so that they function naturally. Such actions can coincide with flood
mitigation to defend against more severe floods while gaining environmental and
economic benefits. Existing policies
will help Kinston/Lenoir limit costs while striving for this three-fold
benefit.
-Flood
mitigation
-Environmental
Benefits
-Economic
Benefits
-Restoration
-Preservation
Explanations of Procedures/ Results/
Discussions
By
removing vulnerable property in the floodplain and requiring residents to
elevate properties, FEMA’s policies have helped prevent future flood
damage. However, stakeholders can also
prevent flood damage by reducing storm water runoff upstream of the
floodplain. Impermeable surfaces like
concrete and asphalt increase the volume and speed of flooding during
rainstorms. For Kinston/Lenoir,
predicted increases in impermeable surfaces upstream (particularly the Triangle
area) threaten to increase flood levels.
Naturally
permeable land can help offset the negative impacts of impermeable land. In particular, forests and wetlands slow
down storm water runoff and redirect it into the ground. Far from uniform, a wetlands’ flood
retention depends on its position in the watershed, the condition of the soil,
plant populations, and other hydrologic factors. Despite this variation, wetlands restoration and preservation is
an important part of successful flood mitigation.
Coming Soon:
- Discussion of climate change implications
- Figures on the percentage of impermeable land predicted for the Neuse basin in 2025.
Through
wetlands mitigation, Lenoir County can contribute to Neuse River water quality
improvements. In its basinwide water
quality plan, the North Carolina Department of Environment and Natural
Resources (NCDENR) developed a water quality ranking based on how each water
body is used, including fishing and drinking water. The report classified the upper Neuse estuary as partially
supporting its intended uses (NCDENR, 1998).
Urban runoff, agriculture (crop/animals), wastewater treatment, and
atmospheric nitrogen, are possible sources of pollution to the estuary (NCDENR,
1998).
Since the
majority of land in Lenoir County is cultivated, the county is a likely
contributor of non-point pollution to the Neuse estuary. Wetlands filter runoff
and remove sediment and nutrients that would otherwise pollute the
estuary. Wetlands mitigation can reduce
the county’s non-point pollution in addition to curbing flood levels.
Coming soon:
- A discussion of the connection between high stream flow in Kinston and nutrient pollution in the estuary.
- Wetlands water quality benefits to farmers.
- Percent of cultivated land in Lenoir County (or in sub-basin).
The NC Department of Emergency Management plans to
remap NC flood plains within three years.
New flood maps will likely show expanded flood plains, requiring more
residents to purchase insurance. As
will be discussed with the policy options, Kinston/Lenoir homeowners will
receive flood insurance discounts with floodplain open space preservation. Along with insurance discounts, the entire
community receives a rating that stands for lower flood risk.
Todd
Davidson of FEMA Region IV, remarked at a recent conference that governments
tend to view their flood risk status as more than a flood insurance
discount. In fact, he said the greatest
economic advantage for them was to promote their communities as low risk and
thus more competitive for potential business.
Thus, Kinston/Lenoir can gain recognition from business for preserving
wetlands in the floodplain.
In or out
of the floodplain, Lenoir County can achieve a net gain in wetlands benefits
through DOT or other developer mitigation.
At no cost to the county, this wetlands mitigation will provide flood
prevention and environmental quality.
With a list of potential wetlands, developers like the Global Transpark,
also can accomplish faster construction plans.
Economic benefits of jobs and tax revenue to the county will arrive
faster as well.
Coming Soon:
-Will existence of wetlands affect flood plain mapping?
-Reducing flood damage is an economic advantage in itself.
Like many
rural counties in North Carolina, Kinston/ Lenoir cannot spare funds or
personnel towards wetlands mitigation.
Luckily, policy options exist that limit burdens on the local
government. For example, flood buy-out
properties have been purchased by Kinston/Lenoir and are being cleared of buildings. Wetlands within these buy-out properties can
be protected. The buy-out properties
also may contain appropriate land for creating or restoring wetlands.
Also
within the floodplain, Kinston can facilitate wetlands mitigation through
FEMA’s Community Rating System (CRS).
As mentioned earlier, residents receive flood insurance discounts if the
local government preserves floodplain open space. Kinston/Lenoir has been interested in stepping beyond the buy-out
program and preventing new development in the floodplain. To receive CRS credit, Kinston/Lenoir can
use this study to begin planning further open space preservation. By favoring wetlands as priority open
spaces, the community will gain environmental quality and flood retention
benefits as well as insurance discounts.
Beyond
floodplain boundaries, the CRS does not provide discounts for open space
preservation, but the Army Corps of Engineers (ACE) operates a wetlands
mitigation banking program, in which developers must compensate for the destruction
of wetlands with preservation or restoration.
This regulation, under the Clean Water Act, has created a demand for
wetlands mitigation and allows for the banking and selling of wetlands
mitigation credits. Kinston/Lenoir can
gain from this program by encouraging developers to bank wetlands credit within
the county. Table 1 explains the
separation of these policy options.
Table 1. Policy Options for Wetlands Mitigation.
Floodplain |
Non-Floodplain |
·
Buy-out Program
|
·
Mitigation Banking through the Army Corps of Engineers
|
·
CRS Open Space Credit
|
|
|
|
Potential restoration sites were selected
using soils, land cover, and county parcels data. In its soil surveys, the United States Department of Agriculture
(USDA) Soil Conservation Service evaluates habitat suitability for each soil
series. The most useful ranking for
this study was the wetlands plants category, with ranks from good to very
poor. Series ranked “good” for
wetlands plants was the first criteria for potential restoration sites.
From land
that contained these soil series, vacant parcels were selected. These parcels would present fewer costs for
restoration since no demolition of buildings would occur. After selecting the vacant areas, the land
cover data was used to exclude any land that already contained wetlands. The final map displays vacant sites that
contain soil suitable for wetlands plants.
Maps:
1.
Land cover of potential restoration sites.
2. A comparison of raw data and neighborhood statistics data.
3. Map 2 with a close-up of Kinston.
Coming Soon: Further Discussion of Restoration Sites
ACE tends
to place stricter criteria on credit for wetlands preservation since
preservation does not result in a net gain of wetlands. Therefore, preservation sites must have
unique characteristics compared to other wetlands. For example, a preservation site could be eligible if it contains
rare species like bald cypress. ACE may
also approve preservation sites adjacent to development or farmland, since
wetlands will filter water pollution from these sites. Water quality monitoring information can
also make a case for wetlands mitigation.
If wetlands are upstream of poor water quality, their protection is
crucial to prevent further decline in water quality.
Through the GIS data available,
preservation sites were selected by considering watershed locations,
bioclasses, and land cover. The
bioclass stations monitor the existence of species that indicate water
quality. Certain organisms are
sensitive pollution while others tolerate high pollution levels. Counts of sensitive organisms compared
across the Neuse watershed help to designate poor water quality sites. Benthos bioclasses give water quality
ratings according to counts of macroinvertebrates (mostly insect larvae) that
live in stream bottoms. This data was
mostly collected in the summer unless a stream’s flow was too low to accurately
collect specimens.
To aid
stakeholders in choosing sites that have the greatest chance of ACE approval,
priority watersheds were selected from the smallest watershed units within
Lenoir County. The watersheds upstream
of very poor to fair bioclasses were selected as priority watersheds. Some watersheds were excluded because they
did not contain bioclass monitoring stations, and other watersheds were
excluded because they did not flow into the Neuse River within the county. Although such watersheds may be important to
wetlands preservation, they were excluded so that Kinston/Lenoir could continue
to focus on mitigating flooding within their own county while prioritizing
preservation sites. The wetlands were
designated according to land cover data with three categories: unmanaged herbaceous wetland,
Oak/Gum/Cypress, and Bottomland forest/ Hardwood swamps.
Maps:
1. Priority Wetlands, Watersheds, Bioclasses, and Land Cover
Map 1 illustrates the potential
preservation sites within the priority watersheds. The map also designates the cultivated, low intensity, and high
intensity land in these watersheds. All
priority watersheds contain nearly 50% cultivated land, but one watershed has
over 70% farmland. Each watershed had
less than 10% developed land. Since
most of the wetlands sites appear adjacent to some kind undesirable land
(either cultivated or developed), further prioritization requires other
criteria. Field studies could determine
which sites contain endangered species, or social surveys could determine
landowner willingness. GIS evaluation
can also be done with NPDS permits and location of livestock operations.
Coming Soon: A chart comparing percent land cover in the priority watersheds.
