Opening Dialogue. Connecting Culture. | Tyson Moultrie for Mayor of NBMA

Flood Protection

Flood Protection

Flooding on Belleville Ave. New Bedford, July 12, 2019. (Photo by: Ed Caron)

Storm Surge Protection

In addition to proactively reinforcing and reactively rebuilding infrastructure and buildings with hemp-based materials, new forms of climate-resilient infrastructure can be erected. With locally produced hempcrete and 3D manufacturing, the construction costs of sea walls, wave breakers and floodwater canals are greatly reduced. Hempcrete can be used as the foundation to create artificial marshlands along the coast branching out from the sea walls and the hurricane barrier. Marshes essentially act as giant natural sponges during storm surges and “soak up” storm surges, slowing them and reducing flooding. 

In many places marshlands act as the first line of defense against coastal flooding. Coastal wetlands prevented more than $625 million in direct property damages during Hurricane Sandy. Sea walls typically damage the natural ecosystem, but with holistic design, the benefits of sea walls and artificial marshes can be merged to create regenerative elevated coastlines. With designs that mimic natural wetlands and the introduction of native wetland flora and fauna, especially shellfish the coastal water would be naturally cleaned of pollutants and carbon making it cleaner and less acidic. This would also create a new source of local food and new habitats for endangered coastal wildlife while in itself being a new tourist attraction/recreational area. Elevated pathways should be constructed above the marsh to create a system of walking trails along with ramps to launch kayaks and paddleboards. Placing IoT sensors throughout the wetlands would monitor its conditions and collect data to further the innovation on engineered resilience against sea-level rise and anthropogenic climate change at the Silicon Seaport.

Re-Permeation 

Much of the flooding in urban areas during storms is due to rain runoff. Concrete, asphalt and brick are not permeable materials meaning they do not absorb water like organic soil. This causes water to flow continuously until settling at the lowest point creating flash floods and huge puddles. Rainwater is supposed to be filtered off the streets through the sewer system however sewers are typically overrun and will certainly be overrun more often during climate change. This flooding damages infrastructure, homes, businesses and disrupts mobility/commerce. This runoff typically finds its way into rivers, lakes and the ocean bringing with it pollutants and garbage. In urban areas up to 75% of rainwater becomes runoff. Along with the urban farming referenced in part 3, other forms of “urban greening” can hugely contribute to mitigating cloud-born flooding. Green roofing is the practice of outfitting urban rooftops, from buildings to bus stops with specially designed vegetation beds filled with water-absorbent plants. Intensive green roof systems absorb up to 90% of would-be runoff. The water collected from green roofs gradually drop-drain over a two month period and this slow pace does will not overwhelm traditional drainage/sewage. The water draining is naturally filtered of most pollutants, especially heavy metals.

Along with absorbing rainwater, green roofs offer a number of added benefits. During the summer months, they absorb sunlight keeping homes and buildings cooler, lowering both bills and the carbon footprint associated with air conditioning. This added cooling will make an important difference during the anthropogenic heat waves that will occur over the coming century. A city with many green roofs & green walls will see the same effect on a large scale, cooling the city itself. Green roofs extend the lives of roofs by acting as a buffer from the elements. The same insulation caused by the organic material also reduced outside noise which is a plus for those living near busy city intersections or highways. In areas with urban farmers, green roofs offer micro-pastures for chickens whose grazing helps to maintain the roof. Perhaps the biggest added benefit is fire resistance. The moist soil of the living plants offers a natural form of fire resistance.

 

Rain gardens follow similar mechanics as green roof systems but are places on the ground. They are best built into existing road, sidewalk and parking lot structures. The plants used in rain gardens and green roofs should be locally-natural non-invasive species that are of great benefit to pollinators, especially bees. Beehives should be strategically placed throughout the urban forestry in spots where they will not bother pedestrians. Bees are integral to a functioning biosphere and a network of urban beehives would greatly benefit rain gardens, green roofs and urban farmers transforming food deserts. Having green spaces throughout the city increases resilience during rainstorms, but also cleans the air of pollutants and cools it during heat waves while greatly bettering the aesthetics making the city more attractive to tourists.

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