The Flooding Threat

Another wave of floods has hit our country – including, this time, some interior areas. Historically, our coastland has always been existentially threatened by floods – carved out as it was from mangrove swamps that had been formed by silt precipitated from the Amazonian waters that pour into the Atlantic and are brought by currents around the shoulder of our continent and across its northern coast. The coastland is between three and four feet below sea level, and the Dutch made it habitable during the 18th century – as they had done in the previous three centuries in their native Holland – through the creation of an intricate network of dams, canals, and sluices (kokers).
The threat from flooding arises from two sources – the Atlantic on the north, and excessive rainfall that periodically overwhelms the drainage system. The Atlantic is kept out by a combination of concrete seawalls, earthen sea dams, and mangrove stands. The latter uses the root systems of the red, black, and white mangrove trees to break the force of the waves and facilitate the accretion of silt to raise the level of the land. The seawalls and sea dams are maintained by the Ministry of Public Infrastructure, and of late, there have been no extensive floods from this quarter, even though it has been shown conclusively that the sea level is rising.
The rise of 0.9 mm annually, at this time, isn’t significant, but plans will have to be made for the future. The mangrove forests are maintained through the Mangrove Restoration and Management Department of NAREI with the assistance of the GFC, the EPA, and the PAC. Their challenge is to deal with the 25-year cyclical changes in the deposit and erosion of the Atlantic silt that removes large swathes of mangroves. There have been limited floods from this source, and as such, efforts at restoration must be intensified.
Most of the floods, then, have been caused by excessive rainfall that overwhelms the man-made drainage system and raises the levels of some rivers and creeks over their banks. The Government is quite cognisant of this threat and has intensified its initiatives to address the threat to our livelihoods and health. In the last five years, they have spent some GY$140 billion on drainage and irrigation, which, inter alia, deals with the threat of flooding. This year, a whopping GY$81 billion has been budgeted in this area.
The principles of the coastal drainage system were established by the Dutch centuries ago, as mentioned earlier, and have not changed fundamentally. Their purpose was to create arable land for agriculture, and this function remains that of the “National Drainage and Irrigation Authority” (NDIA) within the Ministry of Agriculture. Cultivable acreage of between 500 and 2000 acres was laid out in a grid on contiguous plantations, first along the river banks and then on the coast, with a “back dam” mile inland to control accumulated interior water. South-north irrigation canals brought in water to the centre of the plantation, which was laid out in fields separated by east-west cross-canals. The outer edges of the plantation had drainage canals (side-lines) into which the side canals emptied and which ran to the seawall or riverbank controlled by sluices or “kokers”. These sluices would be opened at low tides to expel excess water.
Almost every village, town, or city on our coast was once a plantation, and if they experience flooding, it means the drainage system isn’t working due to a combination of many factors that have to be addressed by the NDIA. Siltation and blockage of drains and canals by garbage, astronomical increases in concreted yards decreasing the permeable area for absorbing water, and closure of sugar plantations – all combined with shorter but more intense periods of rainfall. The Government has created multi-linked canals and sluices in several coastal regions; constantly desilted and widened canals; and worked with local bodies to discourage the dumping of garbage.
But there still remain the flooding. We have to begin planning strategically to move inland.