Letter of the Day | Building on a landslide during climate change

THE EDITOR, Madam:

Over the years, I have attended Jamaica Institution of Engineers’ seminars and have been told of slow-moving landslides in places such as St Mary, where the slippage is barely noticeable, but over time moves entire properties and their boundary markers downhill.

Might I say that it seems that the Tavistock, Jack’s Hill, St Andrew slow-motion disaster has speeded up noticeably? It seems that a few years ago, a ‘developer’ decided to place a ‘development’ on a site with known unstable soil and began to remove vegetation to ‘clear the site’, in common parlance ( ‘Hillside horror’ – The Gleaner , November 21, 2023).

If I remember correctly, in Italy a landslide-prone area was reported to have land slippage reduced by having deep-rooted shrubs and other vegetation planted on its slopes. The effect was to have the roots ‘pin’ the soil down and prevent the rainfall from penetrating too deeply, by the fact of the vegetation sucking up rainwater and preventing sufficient water penetration to allow slippage.

It is clear that the Kingston and St Andrew Municipal Corporation (KSAMC) has forgotten the soil reports for the Jack’s Hill area which is sliding away. The area just below the slippage is the housing scheme of Riva Ridge, which is slowly slipping.

A person I know who lived in the housing scheme, complained that a grille gate was improperly made by a workman I knew, because the owner complained that it was jamming in the frame after a few months. It was discovered that the doorframe was distorting and pinching the gate because of the land slippage.

I have also watched a house that was built on deep piles off Bracknell Avenue in Jack’s Hill near a gully, where, even within just a year or more, there was a visible space under the edge of the house facing the gully, where the soil was eroding.

To slow down the problem at Jack’s Hill and elsewhere (it’s probably not possible to stop it), the Italian solution should be implemented.

CATCH AND STORE WATER

Dramatic climate changes are occurring, and although we may be getting less total rainfall, we are getting it in sudden deluges, where we have to design not on the (now outdated) historical data, but rather, the immediate and projected rainfall rates, which can be measured in many inches per hour – not the gentle rains of decades ago.

An indication of how bad this is was brought home to me by the seawater temperature feeling positively hot when I went fishing off the Palisadoes Road. Needless to say, I didn’t catch anything. Probably because the hotter water has less oxygen for the fishes to breathe.

Also, the droughts and deluges we are having makes it clear to me that we have to catch and store the water when we get it (bigger reservoirs), and slow its flow to the sea (carrying our farmland with it) long enough to not smother our reefs in silt, and recharge our aquifers as well.

HOWARD CHIN, PE

Member of Jamaica Institution of Engineers