Flood gates and pumps
Posted on August 3rd, 2019
Dr Sarath obeysekera
Floor gates pumps and pollution is the subject, everyone, is talking about
If at all SLLDC could protect the 1000acres of flood retention area which was identified under the Canal Development Project, we would not have to install any flood gates or pumps
At that time during nineties canal all canal Banks were cleared and encroachers were relocated And yet subsequently various ministers Influenced SlLRDC to keep their eyes closed when scrupulous landowners and developers filled over 400 acres
Now we are lamenting about annual flooding and the people who have either encroached or who did not follow the minimum mean sea level which they should have maintained during construction are now complaining
I am repeating that pumping Kelani water which becomes salty during the drought which flows towards Ambatale will bring more saltwater into the hinterland
During Dutch and British times Muthrajawela was constructed not only for transportation but also to drain saltwater from Muthurajawela rice fields, which was a very fertile paddy land
Now Muthurajwela has become a marsh Now same European nations are pushing us to pump Seawater into the city
This will deteriorate building foundations and quality of some drinking water from wells in the town
Mammoth two-way pumps are selected for fresh water, but they will not last long due to seawater
When you pump Kelani water downstream of Ambatale water intake more and more seawater will flow upstream
Soon we may drink seawater like fish
Dr sarath obeysekera
August 4th, 2019 at 2:20 am
As with most of major cities close to the sea the developments have been going on in law lying areas. So when these cities expand the people who live in these cities fill up their land to build houses. Colombo is no exception. But that is when the authorities have to step in and install flood protection items. And that is done via a bunding system and pumping out water where necessary. But those involved in the planning has to be very careful about the levels. I suppose authorities like LLRDC gives safe levels for any development in their areas.
What is known as Mean Sea Level is a thing that varies in a country from place to place and year to year. The mean sea level in Puttlam or Jaffna is different to that of Colombo. It has a cycle of 18 years. So if you make one place just flood proof in a couple of years it may get flooded unless adequate allowance has been given. However the Datum ( the level 0.0) is a thing that does not change in a country. Usually it is the Marine Department that does all these and educate the people as well as publish the sea level tables called tide tables for different parts of the country for a whole year. I do not know whether such a thing exist in our country. They were quite helpful to me in the country where I did a similar project. My flood protected area was about 10 km interior on a tidal river. When I calculated the gradient using their info and the river levels obtained from the river level monitoring system ( a scada sytem similar to gsm system) of the drainage department, I found that the gradient of the water level to be about the same as that of our Yoda Ela. So, I was wondering whether it has been constructed by our forefathers with the minimum natural gradient without using any sophisticated equipment.
Considering all these our engineers especially the young ones should check what the foreigners do in these UDA projects as these foreigners who supervise the work will get their salaries and go away, but it is us who will have to suffer if things go wrong. We learnt a lesson in Norachchalai ( under the same not so trained electrical engineer who is in charge of this mega project ) where the machinery that were installed were not properly checked and his chairman got the commission paid in Panama and got away.