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A River For Jaffna

2013 Jun 27

Thiru Arumugam

Jaffna Peninsula has an area of 1000 square km and being flat has no rivers and is totally dependent on the annual rainfall of about 1270 mm, of which about 87% falls during the north-east monsoon from October to December, for recharge of the water table in the underground aquifer.  In the past, water was drawn from wells for domestic and agricultural use by well sweeps, but from the 1950’s onwards pumps have been used to draw water from these wells.  There are nearly 100,000 wells in the Peninsula. This over pumping for agricultural use has drawn down the fresh water stored in the limestone aquifer resulting in sea water percolating into the wells through the fractured limestone, as no part of Jaffna is more than about 15 km from the sea. At present about 30% of the wells in the Jaffna Peninsula are saline. Recent reports from agricultural experts state that more than 4500 hectares of fertile agricultural land have turned saline and have become unsuitable for cultivation.

Within the Jaffna peninsula there are two large lagoons, the Vadamarachchi lagoon and the Upparu lagoon with surface areas of about 77 and 26 square km respectively.  These lagoons were open to the sea and were salt water lagoons but during the north-east monsoon rain water from their catchment areas also collects in them. The total catchment area of these lagoons is about 50% of the area of the Peninsula.

If we are to increase the availability of fresh water in the Jaffna peninsula we need to look at sources alternative to rain in the peninsula.  South of the peninsula is the sea water Elephant Pass Lagoon which    has a surface area of about 77 square km.  It has a catchment area of about 940 square km in the mainland Vanni, mainly consisting of the Kanakarayan Aru and three smaller streams.  During the north-east monsoon these streams discharge the surplus rain water from the Vanni into the Elephant Pass lagoon. From this lagoon this fresh water flows into the sea through the eastern end at Chundikulam and formerly also through the western end Elephant Pass bridge, and is at present being wasted.

During the 1960’s a scheme was proposed to utilise the monsoon rain water running to waste from the Elephant Pass lagoon, for the benefit of the Jaffna peninsula.

KEY POINTS of the RIVER for JAFFNA Project

Key points of the scheme and details of the work done in the 1960s are as follows:

    Close off the openings in the road and rail bridges in the Elephant Pass causeway at the western end of the Elephant Pass lagoon to prevent fresh water going to the sea from this end.  This work was completed.

    Build a bund and spillway at the eastern end of the Elephant Pass lagoon at Chundikulam to prevent fresh water going to the sea.  This work was completed and Elephant Pass lagoon became a fresh water lagoon for a few years but unfortunately the bund was breached by subsequent heavy floods, thus allowing sea water access since then.

    Excavate a 12 metre wide, 4 km long channel, called the Mulliyan Link Channel, from the northern side of the Elephant Pass lagoon to convey fresh water from the Elephant Pass lagoon to the southern end of the Vadamarachchi lagoon, including regulatory gates to control the flow.  About 80% was completed when funds ran out and work stopped.

    Refurbish the existing Thondamanaru Barrage (where the northern end of Vadamarachchi lagoon exits the sea) to make it watertight, and improve the discharge gates to allow for discharge of flood water.  This will make Vadamarachchi lagoon a fresh water lagoon.  This work was carried out but a few years later the wooden stop logs perished and allowed sea water to enter the lagoon.

    Provide a spillway and gates at the southern end of Upparu Lagoon where it exits to the sea, near Ariyalai.  This will make Upparu lagoon a fresh water lagoon. The spillway and gates were constructed but a few years later the wooden stop logs perished and allowed sea water to enter Upparu lagoon.

It can be seen from the above that the scheme was only partially completed in the 1960’s and the key element of the Mulliyan link channel to convey fresh water from Elephant Pass lagoon to Vadamarachchi lagoon was never completed.  In the brief period that Vadamarachchi and Upparu were fresh water lagoons, the benefits to the peninsula were noticeable and many saline wells became potable water wells.

Project Benefits

The benefits of completing this project include the following:

About 13,000 hectares of land can be cultivated with paddy in the Jaffna peninsula.  The area presently cultivated is about 8000 hectares due to soil salinity and other reasons.  This cultivation is entirely rain fed unlike paddy cultivation on the mainland which is watered by irrigation channels.  As it is rain fed, the yield per acre in Jaffna is very poor and is only about one-third of the average yield per acre on the mainland.  If the Vadamarachchi and Upparu lagoons become fresh water lakes, the water table and water quality in the wells will improve, and using lift irrigation it will be possible to irrigate these paddy fields without depending purely on the rain and the paddy land now lying fallow can also be cultivated.  The potential for improvement in yield and rice production is staggering.

About 4400 hectares of land bordering the Vadamarachchi and Upparu lagoons are uncultivable at present as they are saline.  When these become fresh water lagoons, after the salt is leached out of the soil, it will be possible to cultivate this land with cash crops and paddy.

There will be a dramatic improvement in the water quality of the 30% of the Jaffna wells which are now saline.  In many cases the water will become suitable for domestic use and agricultural use, increasing the acreage under agricultural cultivation.

Work Needed Now Complete The Scheme

Thondamanaru and Ariyalai Barrages have been completely refurbished within the last couple of years  and Vadamarachchi and Upparu lagoons are now fresh water lagoons. The remaining work to complete this project include:

Complete Spill Cum Causeway At Cundikulam

At the eastern end of Elephant Pass lagoon at Chundikulam, complete the spill cum Chundikulam causeway, zoned embankment, and flanked embankment with gravel road.  The spill plus causeway will be 2100 metres long and the bund 1400 metres long. When this work is completed Elephant Pass lagoon will become a fresh water lagoon.

Complete Mulliyan Link Channel

Complete the excavation of Mulliyan Link Channel, form a bund and roadway, causeway and provide a control regulator. When this work is completed, fresh water can flow from Elephant Pass to Vadamarchchi and Upparu lagoons as required.

Conclusion

No immediate plans have been announced by the Government for carrying out the above two items of work.  This may be because work has started on the Jaffna-Kilinochchi Water Supply Scheme.  This scheme draws water from Iranamadu tank and supplies potable water to Jaffna.  By drawing water from Iranamadu, the local farmers will not be able to cultivate a Yala crop.  To compensate for this, it is proposed to spend 10 million dollars raising the level of Iranamadu bund by two feet.  But in low rainfall years such as 2009 and 2012 the inflow into Iranamadu was less than its present storage capacity.  Thus, raising the bund is not going to store any additional water in such years, and there will be no Yala cultivation.

A much more viable alternative, instead of raising Iranamadu, is to spend the 10 million dollars earmarked for this on completing the River for Jaffna project, and obtaining raw water for the Jaffna-Kilinochchi Water Supply Scheme from the Jaffna aquifer instead of Iranamadu tank.  This will leave the Iranamadu Yala crop unaffected and in addition provide the benefits of completing the River for Jaffna project outlined above.

In addition, there will be a saving of about six million dollars because the long pipeline from Iranamadu to Jaffna Peninsula will no longer be required.

*The writer is a product of the engineering faculty from its Colombo days. He is the author of the well-revied book “Nineteenth century Medical Missionaries in Jaffna, Ceylon”

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