The recent rash of torrential rainfall across Trinidad continues to cast a bright spotlight on the serious problems of intensified flooding events. The damage to several homes and businesses and the impact on municipal infrastructure has been devastating. Properly conveying warnings of impending storms and floods are urgently needed to give people the opportunity to be proactive in preventing damage to their property and livelihoods (agriculture). Initiatives like early flood warning systems and river flow monitoring can accurately assess when extreme flood risks may occur.
According to the European Environment Agency, annual flood losses across the world can be expected to increase fivefold by 2050 and up to 17fold by 2080. Given the reality of the variations in precipitation levels, Trinidad and Tobago is currently experiencing, these flooding events and disaster seems to be escalating due to climate change and proactive measures must be taken to mitigate the problem.
Nothing says stormwater management and urban runoff control like best management practices through sustainable water retention and attenuation basins, creating infiltration and storage solutions. There needs to be further actions on the feasibility of sustainable flood retention basins across existing flood plains and overflow areas of the rivers in Trinidad. There should be greater movement from the relevant ministries and government agencies to restore floodplains because of their role in flood protection, water management and nature conservation.
Essentially, what the flood retention basins and floodplains do is retain and absorb stormwater, thereby shielding nearby villages and towns from the effects of heavy rainfall. The concept of ‘sponge cities’ which can retain stormwater, purify it and drain stormwater in a natural way is not a new ecological/environmental engineering concept. Rather than extensive dredging and channelling or funnelling the stormwater runoff away, a ‘sponge city’ approach would retain stormwater for its own use (irrigating gardens and farms, recharging depleted aquifers, replacing or replenishing water resources, and processing it so that it can be clean enough to use as drinking/potable water) within set boundaries.
This approach (sponge cities) can include green infrastructure such as rooftop gardens and green roofs by their very nature, designed to absorb rainwater and help to mitigate flooding. Sustainable stormwater management tools such as green infrastructure reduces stormwater runoff and is beneficial for the environment, preventing sewers and surface drainage overflows and removing nitrogen pollution from the rainwater. It baffles me why permeable concrete and porous asphalt cannot be applied to certain sections of the built environment.
Impermeable surfaces do not absorb rainwater, it blocks it, redirects it to the drainage network, which in turn often becomes clogged and super-saturated, resulting in surface water overflows onto the roads, highways, streets, and pavements. Unchecked and unchanged, the flooding will continue. The concept of sustainable drainage makes perfect sense for several parts of T&T.
As part of environmental initiatives that are underway across the globe, my recommendation is that impermeable surfaces (asphalt/concrete) be replaced with permeable paving materials such as grass and gardens, porous concrete. This will allow the rainwater to drain into the soil. The process, known as infiltration, also serves to sustain plant life.
Trinidadians and Tobagonians cannot just leave it up to the Government, municipalities, environmental agencies, engineers and urban planners to place an emphasis on green infrastructure to prevent urban flooding. Citizens must make it their personal responsibility to adapt to climate change, manage waste better, whether it’s recycling waste sustainably, collecting rainwater from roofs or building gardens in and around your homes. It is imperative to take the necessary steps to be part of the overall sustainable stormwater and rainwater management solution through a water circularity approach.
Dr Kiran Tota-Maharaj is a reader in Civil & Environmental Engineering (Water and Environmental Engineering)-Aston University Birmingham, UK & Project Engineer- International Water Security Network.