The ice age is coming, the sun’s zoomin’ in
Meltdown expected, the wheat is growin’ thin
Engines stop running, but I have no fear
Cause London is drownin’, I, live by the river
(London Calling – The Clash)

In Mauritius, stormwater has been treated as waste and stormwater management meant dispensing of surface runoff as quickly as possible after rainfall. Due to the heavy rain caused by successive cyclones in recent days, many homes and businesses were flooded and streets were impassable disrupting lives and damaging property. Are the authorities dabbling with stormwater management?

In an age of climate change, urbanisation and increasingly frequent intense storms and prolonged droughts, we should value stormwater as a resource and not as a waste to be managed. A country does not only incur economic loss from storms but public health risks are increased as much as environmental pollution. During heavy rainfall, untreated stormwater and sewage would flow directly to local water bodies causing contamination of drinking water sources. During visits to flood affected areas, I noticed that many homeowners have experienced multiple flood events which damaged their buildings, disrupted streets operation and prevented safe transportation. It is undeniable that concrete and asphalt dominate our urban landscape. Hence, almost 60% of land is impervious surface in our towns and villages. Therefore, all the water that falls on the roofs and streets are not absorbed by the ground and become surface runoff which mixes with pollutants and bacteria on its way to local water bodies. Streets can be both a barrier to natural hydrology and a big opportunity for a better approach to stormwater management. Therefore, government along with its big infrastructure projects such as metro express and smart cities should bring holistic projects to transform the public realm and create social, economic and environment benefits to all road users. A flooded street is not a complete street. Stormwater management should be a priority for this government.

In an article of the 1st March 2015, I explained the importance of sustainable drainage and stormwater management and mentioned that, ‘Now, the potential environment risk that can be posed when connecting surface water sewers to local water courses is in case of misconnections between the two systems. But both systems are out-dated and have shown failings because during intensive rainfall, the systems can be out of capacity to cope with excess surface water and subsequently cause a widespread flooding.’ Many rivers were obstructed by detritus and burst their banks during the cyclones. And, it proved that directing stormwater drains and canals to rivers instead of flood basins could be hazardous and would create widespread flooding, pollution and damage to the environment. Solutions need to be found and fast. Could we envisage building temporary holding ponds or flood basins in order to contain the flood waters and release it slowly? But eventually, the authorities would have to consider the different sustainable solutions to deal with surface runoff. In conclusion, we need to rethink how to convert a surface from impervious to permeable, how to reduce the volume of runoff into our sewer system and how to infiltrate stormwater runoff into the soil to reduce the risk of flooding across the country. Rainwater will not dry up if we do not plan carefully and ready to invest in appropriate infrastructure!

Rambassun (Sandeep) Sewpal
Chartered Architect, Principal at Sandeep Sewpal Architect