Dear Editor,

Over the years the island has experienced more persistent and heavy rainfall resulting in severe flooding and damage to infrastructure.

With these intense events, we have seen instances in which traditional drainage systems were overpowered by the increased flow and intensity of storm and rainwater run-off. Viable, sustainable solutions must be considered to address this infrastructural dilemma since the island is more likely to experience similar weather conditions in the future due to climate change.

Global warming, a phenomenon associated with climate change, has resulted in, and will continue to influence, heavier and more persistent downpours during rain events. The ongoing impact of climate change will also amplify the intensity of storms and hurricanes, with stronger winds and heavier rainfall.

These weather events could and will most likely overpower the current drainage system. As such, our response to increased flooding brought on by these events must become proactive rather than reactive.

With these considerations in mind, we must look at incorporating sustainable urban drainage systems which allow us to work with the environment, instead of against it.

One recommendation is the creation of more green spaces, a nature-based solution, in urban areas to aid with rainwater run-off absorption. This is necessary as urban areas in Jamaica have been experiencing an increase in population and infrastructural development. To facilitate this growth, there has been an increase in urban creep, whereby soft and green permeable landscape has been replaced with hard, impermeable surfaces. As a result, there is reduced absorption of rainwater run-off by the soil, and traditional drainage systems are the only channels to hold and convey faster flowing and larger quantities of surface run-off.

Green spaces will provide additional support to traditional drainage through the collection, storage, and slow release of water into the environment. These processes allow green infrastructure to act as sustainable urban drainage systems, absorbing and delaying rainwater run-off, which reduces the likelihood of flooding and the associated impact.

However, there is limited space to implement green permeable areas to aid in run-off absorption in urban areas. Fortunately, there is an abundance of buildings with enough roof space to implement green roofs which will act similarly to green spaces on the ground. Green roofs are environmentally friendly and act as a form of climate-proofing. Having many green roofs to compensate for the limited space on the ground can play a critical role in supporting traditional drainage through rainwater retention.

Though the plants/vegetation will only use a small amount of water, the substrate beneath them will absorb a considerably large amount of water, and once saturated will slowly release the water off the roof. Through this mechanism, green roofs will attenuate rainwater run-off and reduce the risk of flooding.

In addition to rainwater buffering, green roofs will act as air filters, encourage biodiversity in cities, and, of significant importance, reduce energy consumption. These roofs can aid in energy conservation as they can regulate ambient and indoor temperature. In hot temperatures the green roof will protect the building from direct solar heat, and in colder temperatures it will minimise heat loss through added insulation on the roof. This protection could reduce air condition usage, which translates into less greenhouse gas emissions. There is also the psychological benefit as it is suggested that people are happier in a greener environment.

The implementation of green roofs, if done properly, has few disadvantages, with the main consideration being the cost, which can be recovered through the reduction in energy consumption. The benefits and functions in urban planning and development should be leveraged by the key stakeholders through green-roof incentive programmes and policies to guide developers and investors with constructing green roofs on existing buildings and new developments.

Ajani Jacobs

Water engineering and scientist