Peter Espeut | A water plan for 2030
Due to advancing deforestation, over 100 rivers dried up on our little island in the 20th century. In my first column of the new millennium (in 2001), I predicted that the big issue of the 21st century would be water. As population increases, we will need more clean water, yet at the same time, we destroy our watersheds for fuel wood and charcoal and to build houses; and we advance the pollution of the little clean, fresh water we have left.
On top of this, climate change is deepening, producing extreme weather events (longer droughts and more violent hurricanes). I predicted that if we did not do something soon to protect our water resources, and to increase the capture and storage of clean domestic fresh water, we would no longer be either the land of wood or the land of water.
Another series of water restrictions are with us! Again!
According to the 1921 census of Jamaica, the total population of the parishes of Kingston and St Andrew (KSA) was 118,309. In 1927, the Hermitage Dam (with a capacity of 460 million gallons) was built by the Kingston and St. Andrew Corporation (KSAC) to meet the domestic water needs of the KSA.
By the 1943 census, the total population of KSA had more than doubled to 238,229. In 1946, the Mona Dam (with a capacity of 825 million gallons) was built by the colonial government of Jamaica with a grant from the Colonial Development and Welfare Fund, more than doubling the stored water to meet the increasing needs of the KSA.
According to the 2011 census, the total population of the KSA had much more than doubled again to 662,426. No new reservoir has been built since independence to serve the increasing water needs of residents of the KMA, and none is planned; the argument I have heard is that more storage reservoirs mean more surface evaporation and more wasted water. So what do we do, then?
It is the egregious lack of planning like this that leads me to continually assert that we really had no reason to celebrate 55 years of Independence, which really was 55 years of mismanagement of our economy and our natural environment.
SUGGESTIONS … AGAIN
I have not been satisfied just to criticise, but the suggestions I have made over the years in this column to improve our water situation have been ignored. Let me reprise some of them.
In building the Hermitage Dam, what the Engineering Department of the KSAC did was to build a 150-foot high, 700-foot-wide concrete blockade across the upper Wag Water River valley, which impounded 460 million gallons of water. There are similar valleys all over eastern Jamaica which could be similarly blockaded. If we could plan Highway 2000, we could plan Water Dam 2030!
At times of heavy rain, the dam becomes full, and the excess river water goes over the lip of the dam, down the spillway, and downstream towards the sea. This shows that if there was a larger storage area, the dam could hold more, making more water available in times of drought.
I am not an engineer, but it seems to me that if we were to build another wall in front of the present Hermitage Dam wall, further down the valley, the storage capacity would be easily increased.
Simple mathematics shows that if a new dam wall was built 100-feet further down the valley, it would hold at least an additional 80 million gallons; if it was built 200 feet further down, it would hold at least an additional 160 million gallons. If the ground below the wall was excavated deeper, the capacity could be increased to become the same size as the Mona Reservoir. National Water Commission, please show me what is wrong with my reasoning!
Again, I am not an engineer, but common sense would indicate that if we were to increase the height of the embankment around the Mona Reservoir, that would increase its storage capacity. According to my back-of-the-envelope calculations, for every additional foot of height, the reservoir could hold an additional 80 million gallons, more or less.
Peter Espeut is a natural scientist and environmentalist. Email feedback to email@example.com.