The rainy season is a time when we start questioning the drainage infrastructure that has been put in place when we see water racing down canals and box drains. Maybe you can identify with the experience of being in town when it rains. You know that if you do not want to get your feet wet with floodwater, you will have to find an alternative route to go from Point A to Point B or wait until it subsides.
Over the past few years, developers build more homes, businesses, and parking lots. This means more rainwater will run off these surfaces instead of infiltrating into the soil that was initially there. We need more drainage to compensate for that; however, the drainage infrastructure does not always keep up with development. It is observations like these that have led me to my research area that looks at decisions for stormwater management and flood mitigation strategies.
Let me give you some background information first before I tell you more about plans for mitigating localized flooding. First, when I say the word stormwater, that means, water generated from rainfall that then flows over land and impervious surfaces. As I mentioned before, impervious surfaces include parking lots, buildings, and roadways. Stormwater is the rainwater that does not soak into the ground after it rains. We know and see it is not just pure, clean rainwater running over surfaces. Along the way, it is picking up pollutants, for example, trash (which is most visible to us), oil and grease, pesticides, sediment, and other contaminants. So, the problem is, sometimes we have too much polluted stormwater that floods our neighborhoods and streets. What if we can mitigate this problem with planning and engineering solutions that mimic nature?
I want to inform you of a technique called green infrastructure, also known as low impact development, that can help to supplement the function of existing, traditional infrastructure such as box drains and pipelines. Green infrastructure, in this context, is a nature-inspired, stormwater management approach that promotes natural infiltration, evapotranspiration, and reuse of stormwater at its source. It is an approach that addresses stormwater runoff quantity and quality, thus reducing and treating the volume of runoff before it enters traditional systems.
Some examples of green infrastructure include permeable pavements, rain gardens, rainwater harvesting, and land conservation. An example of permeable pavements is interlocking pavers. You have likely come across interlocking pavers before. It helps to infiltrate and treat rainwater on site. Rain gardens are vegetated basins that collect and absorb runoff from sidewalks, streets, and rooftops. The natural processes that it mimics allow water to infiltrate, evaporate, and transpire.
Rainwater harvesting, a small-scale measure, is the most common in the Caribbean. That is where we collect water from rooftops and channel the flow into a water tank, or water barrel, and store it for non-potable uses. Land conservation, on the other hand, is a much larger scale measure. It is the protection of natural areas such as forest cover, flood plains and wetland areas, especially in and around urban centers. Wide-scale implementation of the measures described can help to alleviate localized flooding. This is not going to solve every flooding problem, but it can complement existing efforts to address the recurring flooding issues that plague low-lying areas of Caribbean islands every rainy season. To have widespread adoption and implementation of green infrastructure, it would take government investment and action, expert input, along with community action. Green infrastructure will require an overhaul in the approach to stormwater management in the Caribbean. I believe it is due time to do so.
Author: Nicole Barclay,
Ph.D. Assistant Professor,
University of North Carolina at Charlotte, North Carolina, U.S.A.
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