32 minute read
Community + Water
Early cities developed along waterways, which served as major transportation routes before the advent of railroads and automobiles. Although useful in bringing resources and people to and from communities, rivers also bring floodwaters capable of devastating those same communities. Traditionally, the United States relied on structural approaches, such as levees, dams, and floodwalls to manage riverine flooding. These types of structural flood controls cost billions of dollars and often take decades to fund and construct. Structural projects also tend to disrupt ecosystems, reduce the floodplain’s capacity to store excess runoff, and can encourage development in flood-prone and other high-risk or vulnerable areas by providing a false sense of security. If these systems fail, due to age, human error, or a weather-related event, catastrophic damage is possible.
While communities in this region have always faced riverine and coastal storm surge flooding, communities are now flooding more often due to frequent and more intense storms overwhelming drainage systems. To bolster their ability to withstand and respond to future storm events, many communities−such as Denham Springs−are adopting new ways of managing stormwater, such as green stormwater infrastructure. Where prior approaches sought to drain water as quickly as possible, green stormwater infrastructure emphasizes restoring natural systems and creating space in the landscape to hold stormwater until it can absorb or evaporate. These strategies increase a community’s overall capacity to store and manage excess stormwater. Many green infrastructure strategies provide multiple benefits, such as improving water quality and offering aesthetically pleasing outdoor environments that facilitate and encourage active, healthy lifestyles.
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COMMUNITY + WATER recognizes the growing importance of planning for water by creating space to store stormwater in the landscape.
In some neighborhoods, no amount of engineering, landscaping, or infrastructure improvements will protect people and their property. In these situations, local governments can use federal funds to buy flooded properties. Once purchased, all buildings are demolished, and the land is maintained as green space in perpetuity. This strategy, known as a buyout, helps households move out of flood-prone areas while increasing space for water in the landscape, which can reduce excess stormwater in other areas within the community. This strategy may be particularly impactful
for communities near and encircling tributary streams and rivers that flood with backflow when downstream waters rise. Denham Springs is one such community.
In the 2016 floods, the Amite River backed up with floodwaters and highlighted a need for increased stormwater detention capacity. During the recovery planning process that followed, “convert[ing] structures that flood repetitively to open space” emerged as a desired outcome of the park enhancement and beautification recovery project that is considered an important priority in the community recovery plan (Denham Strong, 2017, p. 50). Planning for water in the landscape can help the city achieve this and other recovery goals, such as park enhancement and beautification, by creating spaces that manage stormwater where it falls.
In Denham Springs, creating harmony between Community + Water means restoring and conserving the floodplain. Through enacting an intentional buyout program that targets neighborhoods with high numbers of repetitive flood loss properties, the city can restore natural streambanks and work to conserve the floodplain from future development. In this way, a buyout program can be a part of a holistic approach to stormwater management. As repetitive flood loss properties are converted to green space, adjacent properties and neighborhoods may have a reduction in flood risk. Additionally, the flood-prone area can be redeveloped into a floodable park space with recreational facilities that encourage healthy, active lifestyles, which can improve community health and wellbeing while increasing community resilience to future flood events.
backflow
A condition of downriver or downstream flooding that causes upstream waters to rise and sometimes flood. Backflow can exacerbate localized flood events by blocking the downriver escape route for stormwater, trapping it in city streets, yards, and sometimes homes.
Strategies
Converting Flood-Prone Places into Open Spaces
In some neighborhoods, flooding occurs so often the best way to alleviate flood risk is to buyout homes and have residents relocate to safer areas. This strategy removes people from harm’s way while creating the opportunity to build space for water in the landscape. This is possible because all land purchased through buyout processes is converted into green space, which is able to flood. Through intentional planning, the green space can help alleviate pressure in other flood-prone areas by creating a space to store excess stormwater until it can evaporate, absorb into the earth, or drain through gray stormwater infrastructure.
buyouts
A buyout occurs when a government agency purchases a homeowner’s property. After purchase, the house is demolished and the land is converted into green space in perpetuity. Buyouts are a common flood mitigation strategy in areas that flood repeatedly. Participation is voluntary. Federal payouts are capped at 75% of the building’s fair market value.
Establishing Safe Building Standards
Adaptation to flood hazards most commonly occurs through changes to codes and ordinances that regulate development, such as building height, form, and construction. Communities set minimum standards for buildings to keep residents safe and healthy. For example, they require most buildings to have a working sewer or septic system that doesn’t dump human waste in lawns where kids play. Standards set expectations for safety and relieve the burden for homeowners to know things such as: how big a bolt is needed to secure a deck,the impact of a 10 mph wind on their roof, or if their homes are sufficiently elevated to keep them dry in an anticipated flood. As many communities learn more about their increasing vulnerability to flooding, they adapt their minimum building standards to anticipate greater floods. For example, communities might require homes and businesses to be built a foot or two above ground.
Implementing Green Stormwater Infrastructure
There are many different adaptation interventions that are collectively known as green stormwater infrastructure. Green infrastructure strategies tend to mimic and restore the natural water cycle, meaning they store runoff until it evaporates or it is absorbed by the ground, water-loving plants, and trees. Other strategies, such as rainwater harvesting, collect and store rainwater for non-drinking purposes, like watering lawns and gardens. Many of the techniques can be used in conjunction with each other. It is important to note that green stormwater infrastructure is intended to operate in conjunction with, not as a replacement for, gray infrastructure, or traditional drainage systems.
gray stormwater infrastructure
Gray stormwater infrastructure refers to concrete structures and systems designed to collect and transport rainwater. Traditional stormwater management systems use culverts, storm drains, and underground pipes to move rainwater away from streets, homes, and businesses as quickly as possible. Gray stormwater systems can have negative environmental impacts if they prevent or interfere with natural ecosystem functions, such as preventing the deposition of sediments or fragmenting habitats.
green stormwater infrastructure
Green stormwater infrastructure manages stormwater where it falls, by mimicking or restoring natural water systems. Many strategies use soils, plantlife, or permeable surfaces to store and filter stormwater, which improves water quality while reducing nuisance flooding.
Benefits and Considerations
Ecosystem Services Bolster Community Wellbeing
When natural environments provide benefits to humans, this is known as ecosystem services. For example, in a balanced ecosystem, pollinators such as bees are responsible for pollinating the crops that end up in grocery stores. One major benefit of creating space for water in the landscape is the increased ecosystem services that a community receives. Installation of green stormwater infrastructure systems that use native vegetation to filter and clean runoff can improve water quality for the entire community. People also experience positive physical and mental health impacts from being outside in nature.
ecosystem
An ecosystem is made of the living and nonliving elements that coexist in an area. This includes plants, animals, soils, land, water, and weather.
S E C I V R E S M E T S Y S O C E
S E C I V R E S G N I T R O P P U S
FOOD
FRESHWATER
CLIMATE REGULATION
FLOOD REGULATION AND WATER PURIFICATIONSPIRITUAL/AESTHETICRECREATIONAL WATER SECURITY AND SANITATIONFOOD SECURITY LIVELIHOODS AND ENTERPRISE
SUFFICIENT NUTRITIOUS FOOD
HEALTH
SAFETY FROM HAZARDS SOCIAL COHESIONECONOMIC DEVELOPMENT OPPORTUNITIES
© IUCN WATER 2012
3 Ecosystems provide many services necessary for human wellbeing lifestyles.
H U M A N
W E L L B E I N G
Cost Effective Risk Reduction
Learning to live in harmony with our natural environment is cost effective in the longterm, even if some strategies have substantial initial investment costs. It is important to remember structural solutions often have hefty price tags for initial construction, maintenance, and repairs over time. Additionally, rebuilding repeatedly is also expensive. Adopting more stringent building codes and relocating households out of floodprone areas are cost effective strategies because each reduces the frequency with which communities must rebuild homes, businesses, and critical city infrastructure. Implementing green stormwater infrastructure systems can also increase wellbeing and reduce healthcare costs by creating outdoor spaces that allow residents to connect with nature in ways that benefit the mind and body.
Maintenance Needs
Three Denham Strong action items prioritize the construction, repair, and maintenance of city infrastructure. When designing and prioritizing infrastructure projects, the city should consider not only the installation and anticipated maintenance costs, but also the value and benefit to the community. Some projects, like coupling green infrastructure with bike and pedestrian improvements, may have high initial investment costs. However, they return sizable dividends in economic activity and in improved health and wellbeing for residents−features that traditional drainage or street improvements cannot provide.
As Denham Springs begins to establish green stormwater infrastructure, it should seek training opportunities for staff to learn how to maintain these new technologies. Maintenance responsibilities will differ from the traditional gray stormwater systems currently used by the city. For example, staff will need to learn which plants support and which plants hinder the functionality of a bioswale median. To overcome these learning curves, Denham Springs could arrange for peer-learning opportunities with sister municipalities that do a good job of maintaining similar systems. The community might also avail itself of the free green infrastructure resources offered by the Environmental Protection Agency (EPA), which publishes inspection checklists, detailed instructions for plant upkeep, and remedies to common problems.
Considerations for Buyout Program Success
Create a “Rainy Day” Fund
Federal and state funding opportunities for flood risk mitigation and resiliency projects often require a local match. This means that federal funds will only cover a portion of the project with the requirement that the locality contributes the remainder. To position themselves competitively for funding, many communities establish a “rainy day” fund, earmarked for green infrastructure improvements or floodplain restoration projects, including buyouts. “Rainy day” funds may be funded through a general fund allocation, or through taxes on properties that produce stormwater runoff and thereby exacerbate community flood risk.
Engage the Community at All Levels
Successful adaptation and relocation programs require all sectors of the community to embrace the necessary changes. For example, developers will have to change where and how they build, which they will only do if residents are willing to buy their homes. Furthermore, some of these changes need to happen on private property in order to protect already developed areas of Denham Springs. Homeowners will only voluntarily retrofit their homes with green stormwater infrastructure or relocate from vulnerable to safer neighborhoods if they are fully engaged in the planning and implementation processes and if it is affordable. Denham Springs has an active and engaged community. Future plans and programs should build upon pre-existing strengths in responding to residents’ desires and in keeping residents informed about flood mitigation options.
Local hazard mitigation experts identified having a clear vision as one of the most important factors in creating a community adaptation and relocation project that receives federal funding. Oftentimes, federal funds for relocation programs are available immediately after a disaster. Although one can never know when the next disruption will happen, communities in this region understand another storm or hurricane is likely to occur, creating the potential for another disaster. Having a clear vision with a defined project scope and supporting data, such as vetted addresses, packaged before the next disaster will facilitate completing long, complex funding application processes in a disaster situation. It also increases the ability to seek pre-disaster mitigation funds from private and public sources. Residents need to be involved in creating the vision, so the vision matches what residents want out of their future community. If residents do not understand or agree with the vision and process, they will not participate.
Recognize the Importance of Timing
Adaptation and relocation are not quick processes, especially when government funds are involved. However the faster these programs can be implemented, the more successful they tend to be. Timing also becomes a factor because timeframes for applying for funding are limited. Communities must demonstrate political will to transform themselves, considering the short window of opportunity created after a disaster. Although completing a buyout process can take years, families make decisions about rebuilding shortly after a flood event. Vision and timing work together because households are only eligible to receive one federal disbursement per disaster. In order to avoid duplication of benefits, households that receive money to rebuild are ineligible to receive buyout payments for the same storm event. This process also reduces the cost effectiveness of a relocation program if residents use their own monies to rebuild while waiting for the buyout to be completed.
Conduct Transparent Communication
Another important consideration to achieving success is transparent communication of program goals, plans, and processes. Open communication is necessary to build and maintain trust with vulnerable residents, who may be asked to make drastic changes in their lives, such as relocating. Communication is not a one-way street, simply providing information to residents of what program officials deem they need to know. Program officials need to listen to resident needs and concerns and respond appropriately. Addressing resident concerns by changing program implementation, where necessary, can increase chances of success. Increasing community resilience through adaptation and relocation programs requires collaboration across sectors and agencies. City, parish, and state officials need to clearly communicate their goals in order to avoid developing programs that conflict with the agenda of partner agencies.
Consider Unique Needs of Residents
Residents displaced by a disaster or persons living in a buyout area face unique and complex personal realities that impact decisions regarding whether to leave and where to go. Cities should work proactively to find out where displaced residents are going, what types of support are needed, and what roadblocks residents encounter. The costs of moving are both financial and social. Displaced residents are rarely reimbursed by state or federal agencies for all of their relocation costs. Social costs vary widely by household and are best addressed at an individual level. Cities pursuing buyout programs often realize greater success when they seek to understand the unique financial and social costs of relocation and work to reduce or shoulder burdens entirely. Expanding the affordable housing stock and establishing relocation services for residents can help maintain a community’s tax base by finding residents safe, affordable homes nearby.
Develop Capacity and Leadership
The state of relationships between residents and the city as well as between local, state, and federal officials, can be either a barrier to success or a reason for triumph. Positive working relationships between all stakeholder groups are needed for the buyout process to run smoothly. Poor communication can lead to delays, confusion, mistrust, and resentment among residents. Due to the complex bureaucratic and political structure of the buyout process, it may be necessary to coordinate across federal, state, and local governments as well as with residents and staff from multiple community organizations (Freudenberg, Calvin, Tolkoff, & Brawley, 2016).
Successful buyout programs commonly feature at least one project champion at the city level who serves as a liaison between community members, city staff, and the various participating agencies. Appreciating the complexities of such a position, cities should allocate time, resources, and flexibility for champions to cultivate longterm relationships with agency staff, neighboring municipal staff, and community members, many of whom may be coping with traumatic responses caused by past disasters and episodes of displacement from their homes.
Foster Housing Affordability
Denham Strong advocates for policies and actions that reinforce the affordability of the city’s housing stock. Floods and other natural disasters often increase a community’s housing costs by reducing the number of homes and by causing insurance premiums to rise. Denham Springs can bolster housing affordability by planning for and encouraging the development of more affordable housing opportunities in areas less susceptible to flooding. The city’s plans for a centrally-located, mixed-used Triangle Business District with affordable homes accessible to low- and moderate-income families is a good example. Simultaneously, Denham Springs supports affordability by adopting green infrastructure, while other mitigation measures lower insurance rates.
Community + Water Toolkit
There are many tools Denham Springs can use to reduce flood risk and improve quality of life in the city. While some interventions operate at the community-level, others are designed to be implemented on private property, such as rainwater harvesting. Installing green infrastructure on private property in flood-prone areas can alleviate small scale nuisance flooding by directing runoff to rain gardens and other areas designed as stormwater storage. Because many of these tools require some level of initial investment, communities can craft ordinances and policies that incentivize participation. Cities can also create programs and partnerships with local organizations to provide free technical assistance, site assessments, and/or critical resources, like rain barrels, to help residents to implement these ideas on their property. The following tools and policies should be considered as Denham Springs updates and revises local stormwater management regulations and moves forward with converting repetitive flood loss properties into open space in fulfillment of flood recovery and park beautification goals.
Managing Water at Multiple Scales
To be effective, stormwater management must operate at multiple scales.
Individual
Community
Regional
Green Roofs
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A green roof uses a layer of plants to absorb rainwater. Depending on the design and the overall weight, structural changes may be needed to transform a traditional roof into a green roof.
Implementing Green Roofs
The initial investment of constructing a green roof is significantly more than using conventional roofing practices. However, long-term costs are comparable because green roofs tend to last twice as long as conventional techniques. To alleviate burdens associated with the large initial investment and to make green roofs more affordable, communities can offer subsidies based on the square footage of green roof area created. These types of policies typically establish a maximum, either a set amount or a percent of the total green roof construction cost. Jurisdictions can use stormwater impact fees to fund a green roof subsidy program to help mitigate stormwater runoff from new construction. Green roofs mitigate stormwater by absorbing runoff before it reaches a community’s drainage system. Subsidizing green roof construction on private property is a valid use of public funds because constructing green roofs reduces the cost, size, and maintenance burden of grey stormwater infrastructure. Some communities incentivize the use of green roofs by designating them as permitted obstructions to established lot coverage maximums.
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Rainwater Harvesting
Rainwater harvesting means to catch, store, and use rainwater through a number of different techniques, such as rain barrels, cisterns, and under or above-ground tanks. Captured rainwater can be used for toilets, laundry, lawns, and other outdoor activities; but it should not be used for drinking, bathing, or swimming without proper treatment.
Implementing Rainwater Harvesting
Although rainwater harvesting happens at the individual property level, it provides several community level benefits. Rainwater harvesting can decrease stormwater collection overflows, demand for potable water for lawn and garden irrigation purposes, and energy required for stormwater treatment as well as mitigating costs. To encourage high participation rates throughout the community, many cities use a combination of incentives, compliance assistance, and regulations.
Incentives: Popular incentives include programs that provide free disconnection services and storage containers as well as fast-tracked, streamlined permitting processes for participants.
Compliance assistance: Some cities, like New Orleans, form partnerships with local nonprofits to teach residents about benefits and techniques for rainwater harvesting and provide assistance to set up collection systems on private property. Other communities provide training materials, such as brochures and video tutorials about downspout separation, as well as free assessments and technical assistance to help residents install home collection systems.
Regulations: City ordinances can require new developments to install rainwater harvesting techniques. Requirements are typically determined and categorized by lot size. Implementing rainwater harvesting may require amendments to zoning, subdivision, landscaping, and floodplain management ordinances.
Where: Zoning Ordinance, Subdivision Regulations, Landscaping/Floodplain Management.
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Trees
Trees are a critical component of our ecosystem. In addition to improving air quality and providing shade to reduce the urban heat island effect, trees have the ability to absorb and store large quantities of water. For example, a single oak tree can absorb 1,000 gallons, or 25 bathtubs, of water daily. Street trees also act as a buffer to muffle traffic noises, which supports the quiet, peaceful environment Denham Springs residents desire.
Implementing Tree-Friendly Policy
Although trees provide many ecosystem services and community benefits, their risk reduction properties are often overlooked. In order to meet their full potential, street trees need adequate space and care to mature.
Tree planting and protection: A common strategy to protect the trees that provide the most benefit, such as mature oak trees, is to enact old growth tree protection regulations that prevent new developments from cutting down existing trees. Municipalities can also create tree planting requirements for commercial and mixed-use developments in order to restore the tree canopy within their boundaries. Establishing citywide goals for tree canopy coverage, such as 50% coverage by 2030, is a good way to measure success.
Planting standards: Landscape ordinances that set adequate soil volume and quality requirements help ensure street trees reach their potential to provide multiple ecosystem services. Trees require large planter boxes to obtain healthy soil volumes. They also need proper structural soils and pathways for roots to reach their full size beneath paved surfaces like streets and sidewalks. Creating a healthy environment for trees reduces the time it takes for trees to reach maturity and provides multiple benefits.
Stormwater absorption capabilities of common trees in southeast Louisiana
Tree Stormwater Absorption Per 1 Tree (Gallons/Day)
Live Oak Tree 1
Quercus virginiana
= 1000 gal/day
Bald Cypress 2
Quercus virginiana
Sycamore Tree 3
Platanus occidentalis
Sweet Bay Magnolia 3
Magnolia virginiana
In 1 year, 1 Sweetbay Magnolia tree can make $9.80 benefit by sequestering CO2, avoiding Storm water Runoff and removing air pollution.
www.mytree.itreetools.org = 880 gal/day
= 400 gal/day
= 100 gal/day Stormwater Absorption Per 20 Tree (Gallons/Day)
= 20,000 gal/day
= 17,600 gal/day
= 8,000 gal/day
= 2,000 gal/day
A standard bathtub holds 40 gallons of water.
1-www.soulnola.org 2-Keating, Janis. 2002. Trees: The oldest new thing in stormwater treatment? Stormwater MarchApril 2002. http://www.stormh2o.com/march-april-2002/trees-strormwatertreatment.aspx 3-Book: 50 Hikes in Orange County (Explorer’s 50 Hikes) By Karin Klein 4-https://karolinfelix.com/sweet-bay-magnolia-trees/
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Permeable Pavement
Pervious or permeable materials allow stormwater to pass through them and absorb into the ground, which reduces runoff. Using permeable materials to construct urban spaces (ie: parking lots, roads, driveways, sidewalks, trails, etc) reduces the negative impact these uses have on localized urban flooding.
Implementing Permeable Pavement
Urban environments contain miles of paved surfaces including streets, driveways, sidewalks, and parking lots that disrupt the water cycle by preventing water from soaking into the earth to be used by plants and animals. Through shifting design and construction material standards to emphasize permeability, excess runoff can be reduced. Paved surfaces are categorized as either public or private property and require different policy solutions to facilitate and encourage the use of permeable materials and other green stormwater infrastructure solutions.
Publicly-owned property: Municipalities have a large degree of control over the design of publicly-owned property. Codes and ordinances can be updated to incorporate green stormwater infrastructure into design standards for roadways, public building sites, and bicycle and pedestrian improvements, such as reduced lane widths, pervious paving, tree-planting, and bioswales. Cities can establish pilot projects at local schools and parks to introduce residents to green infrastructure methods they could implement at home.
Private property: Unlike public property where governments are more freely able to dictate design and use, municipalities need to employ regulatory and incentivebased tools to support local adaptation measures for improved community resilience on privately-held property. Two important tools include parking regulations and maximum lot coverage standards, which limit the percent of impervious surfaces permitted on a parcel of land.
Maximum lot coverage: As a first step, municipal zoning codes and ordinances should be updated to set maximum lot coverage standards in all districts regardless of residential, commercial, and industrial purpose. Establishing maximum lot coverage standards for non-residential areas should be a top priority as these uses typically create the most stormwater runoff due to their highest rates of impervious surfaces. Maximums can vary depending on the localized flood risk within a watershed.
Parking regulations: There are many different sustainable parking management strategies that municipalities can use to increase parking lot efficiency and design. Most codes are adapted from the American Association of State Highway Transportation Officials (AASHTO) or similar standards and tend to be one-size-fits-all approaches that prioritize drivers. Developing more accurate and flexible parking requirements can allow parking standards to meet demand while balancing stormwater management needs. Flexible codes may provide incentives such as reductions in parking requirements or increases in square footage in exchanging for installing green stormwater infrastructure. Typical parking lot green infrastructure strategies include: permeable materials, shade trees, planting islands, and enhanced perimeter landscaping.
impervious surface
An impervious surface, like concrete, does not absorb water. Stormwater runoff is created when impervious surfaces, such as roads, walkways, parking lots, and buildings, prevent rain from absorbing into the ground.
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Rain Gardens
A rain garden is a shallow depression or low-laying area planted with native plants that absorb and filter runoff. Rain gardens need well-draining soils and allow stormwater to be absorbed by plants and to infiltrate into the ground.
Retention & Detention Ponds
Stormwater ponds are a common strategy to store and treat runoff. They function by creating a space to hold stormwater that allows pollutants and other sediments to settle. Detention ponds, which only hold water during storms, are designed to drain from a full condition within 36 to 48 hours to allow sediment particles and associated pollutants time to settle and be removed. Retention ponds always contain some amount of water but have extra capacity to hold runoff during storms.
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Bioswale
A bioswale is a broad, shallow ditch with a dense covering of trees, grasses, and other native, water-loving plants. Bioswales, as an alternative to concrete culverts, convey stormwater naturally, promoting infiltration, reducing runoff volume, and filtering pollutants.
Implementing Bioretention
There are many types of bioretention strategies including, bioswales, rain gardens, and retention and detention ponds. These interventions are placed around impervious surfaces to collect and clean runoff where it is generated to alleviate pressure on traditional drainage infrastructure.
Incentives: Popular incentives include tax breaks or reductions in stormwater utility fees, and credits or bonuses for other development requirements, such as an increase to the allowable density on a site or a reduction in the required number of parking space.
Compliance assistance: To encourage homeowners to install bioretention strategies on their property, municipalities can develop how-to guides and help residents connect to organizations that provide site assessments and technical assistance. Implementing public education and assistance campaigns offers the opportunity for cross-sector partnerships to increase community wellbeing and resilience.
Regulations: Development codes should include high standards for on-site retention in non-residential areas. Landscape standards should be flexible to allow the stormwater conditions and needs of the adjacent areas to determine the appropriate intervention, plants, and sub-surface structure to use.
Enhanced Stream Banks
Enhanced stream banks and riparian buffers are created when communities allow trees, shrubs, and other plants to grow adjacent to waterways (ie: rivers, lakes, bayous, wetlands). Forested buffers provide the most ecological benefits, such as erosion control, increased water quality, and habitats that support biodiversity.
Implementing Enhanced Stream Banks
Riparian buffers are often established or restored through local development and zoning codes that identify critical floodways and riparian areas on a watershed scale. Wetlands, riparian areas, and floodplains prioritized for protection or restoration may be safeguarded through restrictions of potential development and the creation of conservation easements.
Incentives: For new projects, jurisdictions can offer double open space credit for the creation or enhancement of riparian buffers along protected waterways. They might also allow the “transfer” of development rights between a floodplain property and another located outside of the floodplain. This effectively stops any development on the property within the riparian buffer and, in turn, supplements the development potential of a property that has less adverse impact on the capacity of the watershed. Finally, jurisdictions might offer tax breaks or fee reductions for properties that enter into conservation easements that protect the riparian buffer.
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Floodplain & Wetlands Restoration
Floodplain and wetland restoration projects focus on repairing or mimicking the natural interactions between the vital parts of any waterway: groundwater, stream flow, and plant root systems. The interactions of these three components provide several benefits, such as filtering pollutants and sediments from runoff to improve water quality, recharging groundwater, or increasing storage capacity to reduce flooding during heavy rain events.
Floodplain and wetland restoration must happen at a scale larger than a single community. Restoration projects use a watershed approach to plan for an entire floodplain, not just the portion within city boundaries; therefore, they require a concerted effort to be made in collaboration with surrounding jurisdictions.
Identifying Areas for Conservation
Conservation seeks to retain or improve the existing ecosystem function of undeveloped or lightly developed land. Conservation plays a critical role in riverine environments as it protects wetlands and open spaces where stormwater and flood water can rest and percolate into the groundwater system. Such land can function as a buffer for riverine flooding. To encourage conservation, some municipalities provide compensation to property owners for a commitment to limit development on key land areas. This type of agreement is called a “conservation easement” and runs with the land.
Conservation Easements
Conservation easements offer financial incentives to private property owners who volunteer to restrict development on their properties. Such easements typically allow for continued use of the property for activities that have little or no impact on wetland ecosystem function, such as fishing, hunting, or sustainable logging. Easements are a flexible policy tool that can be applied to entire properties or just critical areas. Financial incentives often take the form of property tax deductions or credits. Communities should define and coordinate conservation areas in a comprehensive planning process that surveys possible target areas based on their potential to further multiple goals such as equitable access to park and green space, flood mitigation, economic development, and strategic infrastructure planning.
While conservation easements often reduce the amount of property taxes collected, they do not eliminate them entirely, leaving some revenue for the municipality. Many communities use zoning codes to limit the development potential for properties in floodways and wetlands. However, zoning codes that bar development can be vulnerable to expensive court challenges. Conservation easements offer a flexible, conservative alternative to strict zoning rules. Since property owners enter into conservation agreements voluntarily, this tool is only effective in communities where property owners are willing to participate.
Floodable Parks and Stormwater Lots
Parks and vacant lots can be great spaces to store excess stormwater because people typically avoid parks and outdoor areas when it rains. Through intentional planning, parks and vacant lots can be designed to retain stormwater, which can alleviate street flooding and pressure on city drainage systems. Floodable parks and stormwater lots incorporate the native plants and soil compositions used in rain gardens and bioswales to filter contaminants from runoff. This provides the added benefit of improving water quality while storing and absorbing stormwater.
Implementing Floodable Parks
To avoid the challenge of implementing green infrastructure strategies into existing neighborhoods and densely developed areas, vacant or abandoned property and parks can be converted into stormwater lots and floodable parks. To facilitate the creation of these types of spaces, municipalities need zoning ordinances that categorize “stormwater management” as a primary use. Combining these spaces with other development opportunities, such as bike/pedestrian investments or a planning unit development, improves their likelihood of being used as a community gathering-space.
Stormwater Impact Fee
A stormwater impact fee is a one-time fee charged for new developments that fail to adequately manage stormwater runoff on-site. When Denham Springs updates its development codes, it should consider requiring new developments to manage more or all of their stormwater runoff on-site. If a developer can demonstrate that such a requirement prevents them from moving forward with a viable project, the developer could instead pay a stormwater impact fee that the city could apply to green infrastructure projects that offset the increase in runoff due to the development. This assures that community members will not foot the bill to pay for increased demand on local drainage. Denham Springs might also explore offering incentives for new developments that exceed standards.
Developers should only be allowed to opt into paying a stormwater impact fee only if they can demonstrate that conforming to established stormwater standards precludes development on their property. Impact fees must be applied to projects that directly address the negative impact for which they are being collected. For example, stormwater impact fees could not be used to purchase a residential home in a buyout program. As a result, stormwater impact fees should be earmarked as distinct from other funds, such as the flood mitigation fund.
repetitive flood loss property
When a building floods multiple times in one decade, it is considered a repetitive flood loss property. Homes and businesses that flood more than four times in ten years are considered severe repetitive flood loss properties, which may increase the percentage the government is willing to contribute to buyout the property.
Flood Mitigation Fee
Green infrastructure and other flood mitigation measures support the wellbeing, economic vitality, and resiliency of the entire community−not just those living in the lowest-lying areas. Accordingly, some municipalities ask that all community members contribute to help pay for projects that support flood resiliency and raise property values for all. Cities and parishes can offer fee reductions for property owners who make improvements that contribute to flood reduction, like creating a rain garden. When setting up a flood mitigation fund, transparency and defining how the money can be used are important to a community’s strategy. A community should consider the scope of flood mitigation projects that are eligible for funding by federal and state programs and position the city to use its flood mitigation program as a local match to leverage those resources.
Codes & Ordinances
Codes and ordinances are the primary policy tools that transform the vision statements and goals set forth in a comprehensive plan into real, tangible change. Several types of ordinances work synergistically to set a community land use policy. For example, many jurisdictions have ordinances that set standards for stormwater management, landscaping design, subdivision requirements, and general zoning and building allowances. These are living documents that may be updated regularly and refined to reflect the changing needs and priorities of the community. However, care must be taken that when one ordinance is updated, references to the outdated policy are similarly updated in related documents. When standards conflict between two documents, it leaves them open to interpretation in favor of the developer, and can undermine the intention of the community.
Accordingly, jurisdictions considering sizeable or complicated updates to one or more of their land use codes sometimes choose to revise them all in one action. This is called a “Unified Development Code.” It assures that all of the codes are in agreement and working toward a unified community vision. Best practices advise that communities located in regions susceptible to flooding update their stormwater and landscape ordinances to require, at a minimum, that new developments manage their runoff on-site. In Denham Springs, updates to codes and ordinances should also establish requirements for green stormwater infrastructure.
checkerboarding
This describes a pattern of development in neighborhoods where only some homeowners have accepted buyout offers. Some properties are cleared and converted to open space while others remain as occupied housing. The intermittent distribution of houses and open lots can be reminiscent of a checkerboard.
Conditional Leases
Buyout processes take time. Often a year or two passes from the initial expression of interest by the homeowner to the day the homeowner receives a check for their property. Homeowners rarely sell their homes and leave in a coordinated way. As a result, a settlement pattern called “checkerboarding” has become an unavoidable phase in most buyout programs.
Some communities have successfully employed a conditional lease program to support homeowners through the buyout process. Under a conditional lease, a city or parish purchases a property at market-rate. As part of the deal, the city or parish agrees to lease the property back to its owners until they are ready to move or until the building is rendered uninhabitable. This arrangement has proven particularly effective for properties occupied by renters as it allows the property owner to commit to restoration without immediately losing the property as a source of income. Conditional leases transfer the burden of waiting from the homeowner to the city or parish, allowing homeowners to receive payment quickly and apply it to a new home. The city or parish should review the availability, affordability, desirability, and safety of its housing stock and consider incentivizing or subsidizing the expansion of local housing stock as necessary.
Conditional lease programs have a few drawbacks. They are not commonly funded by state or federal agencies, which leaves local governments to bear the initial cost of property acquisition. Local municipalities can purchase properties with lowinterest loans and use the income generated by the conditional lease to cover the loan payments, leaving the city or parish budget unfettered. However, homeowners who live on fixed incomes may struggle to afford lease payments. Additionally, this program allows people to stay in their homes, which leaves them vulnerable to the next disaster. As such, it is important to remember that households may require different strategies to enable participation. Successful programs provide multiple options to accommodate resident needs.
