19 August, 2017

Desalinised Water For Jaffna Peninsula – Is It Necessary?

By Willie D. Joshua

Willie D. Joshua

Expensive, unnecessary and environmentally damaging desalination projects for Jaffna can be totally avoided by a simple study to measure groundwater availability and optimised, evidence based water use management methods.    

There have been many articles in the media about the necessity for a desalinisation project to supply potable water for Jaffna. The reason often quoted is that there is freshwater shortage due to over-usage of groundwater resulting in salinity and pollution. This reasoning will be correct only if it could be proven quantitatively by actual measurements, that the fresh water is insufficient for agriculture and domestic use. So far, no one seems to have made any systematic studies in estimating the actual quantity of available fresh water for human use throughout the dry season. This should be given the utmost priority and done immediately instead paying only lip-service. It can be only be proved by measuring salinity of water at different depths because fresh water is underlain by saline water. In addition, this information can be used to predict to what depth the wells should be dug to keep the water free of salinity always.

Computer modelling to quantify fresh water is not likely to be applicable to such limestone aquifers. Due to randomness of dissolution channels and pores, modelling inputs such as transmissibility and specific yield are widely variable at different locations, and it will not be possible to get reasonable results.

Illusion or fact

It has been proven beyond any doubt that the average rainfall during October to January recharges the aquifer with fresh water to much more than its maximum holding capacity ( Arumugam 1971, Wijesinghe 1973, Joshua et.al.2013).  Only in occasional drought-years is maximum recharge not attained. By April-May, almost sixty percent of this overall storage of groundwater seeps to the sea/lagoon by subsurface outflow. This rapid depletion is a consequence of the increased outward pressure caused by the high watertable at the end of the rainy season. Normally, the stored water remaining after May is similar every year and has been sufficient for intensive agriculture and domestic use even for a population of 700,000 in the 1970s. So, is this water shortage and salinity, an illusion or a fact?

Groundwater formation and properties

Percolated rainwater into soil forms a fresh water layer, in the shape of a convex lens over the denser seawater in the aquifer. The lens will be thick at the centre and thins out towards the coasts.  In all probability, Vadamaradchi, Thenmaradhi, Valikamam and the Islands have separate lenses of fresh water.  In reality however, the lenses have fresh water only from the watertable down to certain depths, while the lower part of the lenses consist of a transition zone of increasing salinity. The transition zone is at variable depths at different location and probably results from the diffusion of salts from the underlying seawater into the lens. The existence of the transition zone has been proved by actual measurements (Arumugam-1971, Balendra 1969 and SMEC 2006). The thickness of the lens keeps on decreasing during the dry season with human usage and slow seepage till it is replenished by rainfall. For every unit drop in the watertable, the lens-seawater interface at the bottom of lens rises by about forty units due to density differences.

Depth of wells and salinity

Salinity in wells can be due to several reasons, not necessarily due to shortage of fresh water.   The commonest of all reasons is that the bottom of the well is in the transition zone.   Another reason is that the farmers irrigate large areas from a single well by excessive pumping and consequently a cone of saline water rises up into the well. In Chunnakam, the transition zone was at a depth of 29 meters (conductivity 2000 micro Siemens/cm-SMEC). The salinity of drinking water is considered to be less than 500 ppm of chloride or in conductivity units, less than 1000 micro-Siemens per cm; seawater being 35,000 ppm of chloride or conductivity of 50,000 micro-Siemens per cm.  Sometimes the depths of wells are such that the transition layer may rise into the well making its water saline only in the dry season. Therefore, wells must be dug such that their depth is above the transition zone in late August. It is imperative to determine the cause of the salinity rather than guessing that it is caused by freshwater shortage

Suggested remedial measures

It is important to immediately quantify the amount of available freshwater, if it has not been done already.  Only then will it be known whether remedial measures are needed to get additional freshwater.

Quantifying the freshwater is possible by having a network of boreholes in a grid in the peninsula and measuring the salinity of groundwater periodically at different depths. Alternatively, the same data can be obtained electronically without actually drilling the boreholes. This will require special equipment which SMEC has already identified. This investigation will involve some expenditure but much less than transporting freshwater from an external source. Reverse-osmosis desalination on the other hand is too expensive for Sri Lanka, both for installation and later with recurring expenditure.  It may be even better to opt for water conservation by adopting drip system of irrigation in the peninsula. Drip irrigation, done correctly according to specifications, not only saves water but also eliminates pollution. Remedial measures should be affordable, cost effective, environmentally safe and practically feasible without depriving other areas of freshwater.

Groundwater pollution

Several wells in the Jaffna town-ship have been contaminated with nitrates and e-coli greater than WHO’s safe limits. The pollution is due to ill-designed septic tanks or their proximity to wells. Pollution can be overcome by constructing the long overdue sewerage system with a sewage treatment plant for Jaffna.

In agricultural areas, excessive use of fertilisers and over-irrigation tends to leach the nitrates into groundwater. This type of pollution can be easily overcome by regulated application of fertilisers and by good irrigation practices. The above two pollution problems are the result of human behaviour and can be easily overcome by strict management practices.

References

  1. Arumugam S (1971)   Development of groundwater and its exploitation in Jaffna Peninsula.- Transactions of Institute of Engineers. Ceylon 1. 31-62.
  2. Balendra V. S. (1969) Salt water-Fresh water interface studies in Jaffna Peninsula-Sri Lanka Water Resources Board report.
  3. Joshua W. D. et. al.  (2013) Seasonal variation of water table and groundwater quality of the karst aquifer of the Jaffna Peninsula, Sri Lanka – J. Natn. Sci. Foundation Sri Lanka 41(1) 3-12
  4. Wijesinghe M.W.P. (1973) Groundwater Hydrology – Annual Sessions of the Ceylon  Association for the Advancement of Science, Colombo. 
  5. SMEC (2006)  Snowy Mountain Engineering Corporation, Australia-Jaffna Peninsula Water Supply and Sanitation Feasibility studies ,
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Latest comments

  • 1
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    This comment was removed by a moderator because it didn’t abide by our Comment policy.For more detail see our Comment policy https://www.colombotelegraph.com/index.php/comments-policy-2/

  • 4
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    Thank you, Dr. Joshua. I hope you will be able to visit us soon and do some of these studies yourself. We cannot keep building and using water without knowing what we are getting into.

  • 2
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    Only Tamilians live in Jaffna. So doesn’t matter to others.

  • 3
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    Common sense suggests that the writer is correct in urging caution instead of rushing into expensive projects that are likely to do immense damage. One problem is the shallowness of our intellectual culture that is enhanced by remunerative projects being offered by foreign donors. It pays to submit reports favourable to these projects rather than think problems through. At a discussion where some influential engineering professionals were pushing for water to be brought from Iranamadu, the real justification it turned out was not principally to do with a water shortage in Jaffna, but with the need to industrialise Jaffna – otherwise, they say, where would the jobs for the youth come from? Of course one should promote software industries and non-heavy industries that could be remunerative without needing large quantities of water.

    The other important factor is corruption. There is little effort at making the environment viable and the water cleaner by stopping the plastic waste one sees everywhere. Instead, while turning a blind eye to this, for the short-term benefit of a few several high rise buildings and hotels have come up in Jaffna. No study has been done on how this would affect the water in the area, especially the residential city, and the consequences of huge amounts of sewage being dumped into the ground. There is no sewage system in Jaffna.

    One knows that in this country one could build anything anywhere provided hefty bribes are duly paid. Much of this construction in Jaffna was done during the late and postwar years. Funnily besides, it is now forbidden to excavate sand in Jaffna, and yet buildings are sprouting up on a large scale. We will soon begin paying for all this folly and corruption.

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      No systematic studies have been made…, says the writer. Many a specialist including Israeli experts have made in depth studies over six decades before positive conclusions were reached about desalinisation.

  • 1
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    Dr Joshua’s research based article is timely. Without doubt studies should be done to verify current ground water resources immediately, not only in Jaffna but in many other parts of the country adversely affected by the drought. It certainly does seem that these areas are prone to frequent fresh water deprivation even during times not declared as droughts. Water desalination must be considered as an option, if rain water harvesting produce is insufficient. Water desalination is standard practice in many countries in the Middle East and Israel. Whilst cost is not a major factor for these economies, given the wanton expenditure by most Sri Lankan Ministries, expenditure on water desalination projects in comparison is far is less wasteful, besides having a far longer shelf life. Using solar PV for energy generation for these relatively high energy consuming projects would also partly reduce their burden on the CEB grid as most affected areas have, if not anything else, an abundance of sunshine.

  • 2
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    This water debacle is one thing that undress the Eelam history. One does not need to be a historian to see the stupidity and emptiness of the claims by Eemalist history ( pioneered by tamil politicians) but simple common sense would be enough. Every ancient civilisation had one common thing, access to water.
    The Huang He in china, ganges in North India to Bangladesh, Nile in Egypt, and of course Mahaveli in our Sri Lanka played a defining role in the formation of civilisation. If there is no water access, there is no human civilisation. This is exactly why Jaffna cannot give birth to a civilisation.

    • 4
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      PATHETIC……..

    • 1
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      Eelam is a political question, whether you are for it or against it. Ridiculing the idea is the worst way to confront it. Between 1977 and 1985 almost an entire generation of Tamils thought some shade of it was inevitable and many dedicated persons gave their mind to it, not from the West but while living through all the privations at home. The question of water did occupy their mind and a particular, politically dangerous but not ridiculous, example studied was Israel. If as a Sinhalese you want to address the problem, don’t ridicule Eelam, but try to understand its origins.

      • 0
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        The basis of the Eelam political question is the Eelam history invented and propagated by tamil politicians. The tamil politicians made the Tamils in North to think that Sri Lanka is essentially a Tamil country where an age old Tamil kingdom existed since 3000-2500 years before. I see the Jaffna resident is quite unaware of it. Go through what the fathers of Eelam project told in public gatherings like GG Ponnambalam, Chelvanayagam and even Wiggie today.

        Eelam history is and will be the ROOT cause of Eelam political ideology. This lack of water access in Jaffna is enough to understand why there cannot be an ancient civilization in Jaffna.
        And please learn Israel history. There is a reason why every power devolution debate ends with a history debate in CT

        • 1
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          In all nationalist confrontations people feel the need to spruce up disparate remains into contiguous history. The claim about the Tamil Kingdom going back 3000 years is a mirror image of Sinhalese nationalist claims. We need not waste energy and blood over these claims. History is more complex, demanding and more full of surprises than we like to admit.

          Just go back to your Mahavamsa which gives the social composition of Anuradhapura about 200 BC, during the reign of Pandukhabaya. The Jains were influential in Anuradhapura as traders. Where did they come from and what language did they speak? You dig a little more and you would find that the seaborne trade was carried out between Kaveripattinam and likely Mantai, probably the same route taken by Elara and by Sena and Guttika before him. If you have a healthy curiosity, that is a good place to start, and perhaps relieve history of the burden of having become a hegemonic discipline.

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            what are Sinhala nationalist claims? That Sri Lanka is Sinhala homeland? Is that a nationalist claim? even if it is, is it similar to the tamils’ claim that a tamil kingdom existed for 3000 years?

            The very basis of tamil nationalist discourse in SL is mythical Tamil history propped up by tamil politicians. You may not like to waste any energy on history, but lakhs of people had to sacrifice their lives in this country because of Tamil nationalist history.

          • 0
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            Just go back to your Mahavamsa which gives the social composition of Anuradhapura about 200 BC, during the reign of Pandukhabaya. The Jains were influential in Anuradhapura as traders. Where did they come from and what language did they speak? You dig a little more and you would find that the seaborne trade was carried out between Kaveripattinam and likely Mantai, probably the same route taken by Elara and by Sena and Guttika before him. If you have a healthy curiosity, that is a good place to start, and perhaps relieve history of the burden of having become a hegemonic discipline.////

            So you are saying people from South India particularly TN visited SL? And who is negating that? Do you realise there is a lot of difference between people from South India coming to SL and having a 3000 years old Tamil kingdom in SL.

          • 0
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            Sri Lanka’s problem, or Tamil national problem as it is called in Sri Lanka can never be solved without taking an honest look into the origins of the conflict. And it cannot be solved by shoving what Tamil nationalists like on Sinhala people using India’s or Wests support. Neither can it be solved by doing only what Sinhala people want.
            To solve it, one would need to do a good analysis on that. It will show the role Tamil Historical narrative has played all these time. Correcting that narrative is a bigger part in this.

        • 1
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          The Bloody Nuisance is looking for her padikkama. Go fetch it else she is going to be very crossed with you.

          • 0
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            Some one is hurt..LOL as if we care!

    • 1
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      Sach the stupid,

      “If there is no water access, there is no human civilisation.”

      Then how did Tamil Eelam survive for the last thousand years?
      The water problem in Sri Lanka is not restricted to Jaffna, there are several places in the South with similar problems. This has nothing to do with the Tamil Eelam civilization. Even during the time of the Jaffna kingdom and later during the colonial rule such problems existed.

      • 0
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        No the rest of the island does not have a similar water problem. The water problem in Jaffna is specifically related to lack of resources. There is no river in Jaffna. Without a river how can ancient civilisations start?

        /Then how did Tamil Eelam survive for the last thousand years?///

        Good question…probably because nothing called Tamil eelam ever existed.

  • 0
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    This comment was removed by a moderator because it didn’t abide by our Comment policy.For more detail see our Comment policy https://www.colombotelegraph.com/index.php/comments-policy-2/

  • 1
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    The writer’s views on remedial measures are commendable.
    Jaffna had a tradition of water conservation which was also encouraged by the colonial administration. Direct rain harvesting and sub-surface accumulation are both important.
    A practical problem is the change in lifestyle (especially consumerism) and attitude towards community. Diligence and frugality which characterized the Jaffna Peninsula at one time have almost disappeared. We need to seek ways of reviving healthy attitudes.
    Jaffna’s need for fresh water from outside Jaffna will rise owing to changes in life style, especially relating to water consumption. It will seem immoral for a wasteful society to demand water from the Iranamadu tank. Thus the peninsula should do something to help itself before seeking other sources. Besides water conservation work, the proposals by Arumugam should be pursued in earnest.
    *
    The economy of reverse osmosis desalination is, however, contextual, and the method could be justified under special circumstances and no answer to the general need of the peninsula.
    Also, the discharge of the concentrated salt water has to be done with attention to environmental impact.

  • 1
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    There are many medical issues relating to consumption of purified water by Reverse Osmosis ! The World Health Organization has conducted many studies on this regard. many studies revealed health risks associated with drinking demineralized water. I guess one need to set up a genuine discussion involving Multi Disciplinary / Professional members of this country plus WHO Sri Lanka. In wealthy countries who use this water have enough supply of supplementary pills to their citizens to to take care of the deficiencies. People who live in North are the mostly remaining poor people. Think before Act !!

  • 0
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    The ‘Arumugam Plan’ for a ‘Jaffna River’ is the key to solving the water problem in the Peninsula. Engineer Mendis, who is quite old now and is an ardent advocate of this plan, should be consulted extensively. The side benefit that will accrue from the implementation of this plan, with modifications if needed, will be that an additional 11,000 acres of land will become available for agriculture.

    In parallel, drip irrigation and green house agriculture ; prudent fertilizer and pesticide use should be not only encouraged but also legislated. We need a well informed and empowered and dedicated agricultural extension service.

    Israeli expertise and technology should be be sought and introduced, to minimize the waste of time and expenditure involved in trying to re-invent the wheel. Let us not make this an opportunity for our officials to globe trot!

    Dr.Rajasingham Narendran

  • 1
    0

    An excellent article that requires the immediate attention of all who are concerned about the welfare of the people. It is a pity that such an innocuous subject should attract ire of the likes of ‘Jim Softly’ and his ilk.

  • 1
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    The article specifically emphasizes the fact that it must be first proven that there is really a shortage of fresh water. Instead, the comments pre-assume that there is a shortage and a water problem in Jaffna. Either the NPC or the water resource board or the NWSDB should formulate a project proposal to SMEC to evaluate the depth of freshwater and/or the transition layer at first. It looks as though SMEC has already done some work in NP. If necessary, the River for Jaffna, water conservation etc. can be decided after the amount of available fresh water has been obtained. A systematic and scientific approach is necessary if there is indeed a problem.

    • 0
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      Truth seeker,

      The water issue has been a perennial problem in the Jaffna peninsula. Remember the ‘ Jaffna River’ project was conceived by a Dutch Engineer during the Dutch Colonial era!

      There have been many studies over the dacades and a few centuries! When will we concur we have problems and find ‘Least Cost’ long term solutions?

      Dr.RN

  • 3
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    Barathan

    I did work with the Israeli, Russian and Americal specialists on groundwater hydrology in Sri Lanka. Israeli mainly worked on the Latosol soil area from Puttalam to Pooneryn to Mullaitivu. Israeli specialist also worked in the Jaffna Peninsula on few boreholes to study groundwater. These are reported in Arumugam’s paper. What all the specialists told us was that the lagoons at sea level cannot recharge groundwater.

    At meeting with GA Jaffna then, the Israeli told us that over-pumping of wells can cause the underlying sea water to cone-up and make well water saline. So that we have to carefully manage the groundwater to avoid salinity. The GA suggested that we should slightly exaggerate to say that Jaffna can become a desert if we don’t manage the groundwater properly. This was said mainly for the farmers to be careful in using the water.
    Kindly let me know the references of the in-depth studies done on this topic other than computer modelling. I may have missed it.

  • 0
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    Dr.Joshua,

    ” What all the specialists told us was that the lagoons at sea level cannot recharge ground water “

    I live close to the Navatkuli lagoon. Our two wells hold reasonably good quality water in plenty until the nearby lagoon runs dry. Even during this dry phase, there is sufficient water in our wells for our use. However, as soon as the rains arrive and some water accumulates in the lagoon, the water levels in our wells rise.

    What is the explanation?

    Further. note that the barrages at Navatkuli and Thondamanaru lagoons were reconstructed by the last government. The Sea water has also been blocked from entering the Elephant Pass lagoon.

    Dr.RN

  • 0
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    Well written article by Dr Joshua. The population of Jaffna survived on this water for thousands years due to the fact that the population was small and the modern pumping system has not existed for large scale cultivation as it is now. Recently I heard a story from a Jaffna academic regarding overuse of water from a well in Maravanpulavu. Apparently heavy water use from the well has made it salty and the farmer has learnt the lesson.

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