River for Jaffna

Kanagarayan River

Diversion Canal Project

BY

BALA MANICS

The purpose of this project is to provide Irrigation water to Land around  Killinochi Irrigation Area covering Uriyan, Yakachi areas in Killinochi District and fresh water to the community of the Jaffna peninsula by transforming the saline intruded water in  Vadamarachi East Lagoon(VEL) into a fresh water in Stage 1 and thereafter gradually extending the process to other similar lagoons, like Vadamarachi North Lagoon ( VNL) and Upparu Lagoon. The VEL and VNL have a  combined storage capacity of 69 GL at +1.0m aMSL. 

Project Executive Summary

The nearest water resource to transport water to VEL during the dry season is Iranamadu Tank   (IT) which is about 31 km south of VEL. Under the Asian Development Bank  funded Jaffna Water Supply Project, the bund was strengthened and raised to store approximately 148 GL in the Tank which includes about 18GL of water reserved for Jaffna Water Supply. 

 

Farmers in Killinochi Irrigation Area ( KIA) have raised concerns that transferring water from IT  to VEL may deprive them of getting adequate irrigation water supply for Main(Maha) and Second(Yala) cultivation. Farmers said  that the IT was designed to supply water to 8500 ha gazetted Irrigation land with a cropping intensity of 1.5, i.e. 8500 ha for Main(Maha) and 4250 Ha for Second(Yala) season. However, in reality, not all farmers in the  KIA cultivate their lands. Hence,  there is an opportunity to purchase the unused water and apply it for beneficial use. This practice of water sharing, and trading is well-established practice worldwide and is becoming more prevalent due to various environmental and economic factors.

This proposal is made possible  by using:

  • 3GL of good will water share offered by Killinochi Irrigation area farmers to increase Nett district productivity.
  • Infrastructure built as part of this project will be able to capture about  15GL of excess water during Main(Maha) season at the causeway across Kanaga Rajan river on the Murasumoddai-Vaddakachi Road which  would otherwise flow into the sea via the EPL.
  • Part of above 15 GL could be able to reuse through drainage reuse pump to existing Gazetted Land and thereby conserve the water in IT as a water saving
  • Purchasing the unused water from the farmers  who do not undertake Second(Yala) cultivation (and  some farmers  in Main(Maha) cultivation)  and retaining it  in storage in the Iranamadu tank.

It is possible to procure  and store a total of about 15GL and store in IT and  convey to VEL by gravityThe transfer of water will only occur in the months of July and August each year to raise the water level in  VEL to suppress  intrusion of seawater by capillarity action during the dry season, This will be useful, until the break out of the monsoonal rains in October – February. 

The capital cost of the project has been estimated at Rs 8.7 billion.

This includes  a 5.73 km  water conveying concrete lined channel from the pool to upstream of the Uriyan tank. Thereafter three parallel 1400mm diameter, 12.66km long pipelines (polyethylene HD pressure pipes) will  be used  to transfer the water across the EPL along A9 Road to Pachillapalli. From there water will flow via the new Mulliyan Canal to the VEL to a level  +1.5 m a MSL. This water could be used to supply the proposed Sarasalai Pumping Storage tank for JWSS  as approved by the cabinet. It should be noted that this water transfer infrastructure could be utilised continuously for the remaining  10 months, subject to the availability of water .

The capital cost of the project has been estimated at Rs 8.7 billion.

The Operating cost is Rs 3million per annum at today’s prices.

The Maintenance cost is Rs 6million per annum at today’s prices. This amount also includes an allowance to carry out major periodic maintenance every 10 years.

The Net revenue for this project is Rs 1.745 billion per annum. This is based on a very conservative estimate of only 50% of the 12,000 Ha is productive.

"This is a unique and innovative engineering project to harness the extremely limited water resource available to the Jaffna community. The numerous environmental, ecological, and economic benefit of the project to the Jaffna peninsula are more fully detailed in the report. The successful implementation of this project will lead to further harnessing of the limited underground and surface water resources available and will rejuvenate numerous small tanks spread across the landscape of Jaffna peninsula. ."

– Bala Manics

Project Executive Summary