Preparing for a disaster
Saturday, August 18 2012
THE EDITOR: The teams that have been here for six days removing mud are called Disaster Preparedness. But what they really are is Disaster Response. If there was more Disaster Preparedness, fewer things would have gone wrong. People at Preparedness (or maybe even Disaster Avoidance) would see to it that the drainage systems are adequately designed, built and maintained so there are fewer disasters in the first place.
Many people live in the northwest, in and near Port-of-Spain. Development around the capital started hundreds of years ago on the valley floors, where the plantations were. The land was rich and fertile from hundreds of years of organic matter flowing down from the hillsides. When the plantations went away, people built homes and businesses on the flatter land there in the lower-lying areas. So most people live in the valleys between steep hills from 1,000 to 2,000 feet high. Most of the roads are on the valley floors, too.
Rain becomes surface water and funnels down between ridges to streams and ditches and quebradas and drains and rivers and out to the sea. This movement of groundwater is part of what is called hydrology and much is known about it.
Development always moves away from built-up areas to the open areas on the fringes. In the Port-of-Spain and Diego Martin areas, this means up-valley and on the hills. More uphill and upstream structures are built, more is paved, less rainfall is absorbed, runoff increases, etc. These phenomena, processes and consequences are also well understood and well-documented.
The current drainage system in Diego Martin is an old design that is inadequate to keep up with growth over the years. Rivers and canals are not regularly dredged of the rich soil coming down from the forested mountains, restricting their carrying capacities. Trees, branches, and limbs come down, too, and people all along the stream throw all kinds of debris, organic and otherwise into this moving dumpster, which adds to the clogging of the system. Much of this rich soil from the mountains that fills the rivers could be captured and relocated to farmland instead of letting it run out to sea, but it isn’t.
All along the streams and rivers are low bridges. Debris — trees and parts of trees, sometimes lumber, other stuff, too — snags on them, restricting the flow volume, slowing the drainage process, and raising the upstream levels. Get a bucket and a hose. Turn the hose on and observe what happens when the bucket’s already full. Keep the hose on for a couple of days. Observe what happens when the water spills over the sides.
This was a series of days of long, heavy rains instead of the typical, shorter, more frequent rains. Still, in a year and a half I’ve seen more rain three or four times that, so it was not unnatural or alarming. During the heaviest rains, the water would creep up a few inches in the yard and the carpark, but wouldn’t cover the bottom steps at the front or back doors. There is a concrete block security wall around the 24-townhouse compound that I just learned seems to have been serving levee duty, too. When a hundred-foot section toppled into the river, here came the angry brown water, very quickly and lots of it, because the river was already over the banks. The effect was small-scale catastrophic, and occurred this time right where we live. And this was only our small experience. People in many areas have similar situations — along the Maraval Saddle Road comes readily to mind.
There are three possible steps to take next: make safeguarding people’s lives, homes, and property a priority and fix what’s broken, take some temporary measures that will not solve the core problem, or do nothing at all. The last two will work only if it never rains again.
David Allan Van