MEDIA AND MISLED PUBLIC: Western Terai Flood Problem

By AB THAPA

At present the natural drainage of the Western Terai is blocked by a network of canal system which have been built just across the border in Indian territory . The canal system running almost parallel to our border starts from the Lower Sarda Barrage in the west and ends up in the Banganga ( Rohini) River. The total length of this canal system is 258 km. There are five barrages along this canal system in Indian territory . They are Lower Sarda Barrage, Karnali Barrage at Girjapur, Saryu (Babai) Barrage, West Rapti Barrage (Laxmanpur) and Rohini (Banganga) Barrage. This canal system has been built in anticipation that the regulated flow of the Mahakali and Karnali or the West Seti rivers would be soon available after the completion of the proposed storage dam projects. The canal network has been designed to draw water from various rivers like the Babai, West Rapti and Banganga also apart from conveying the regulated flows of the Mahakali and Karnali rivers. It appears that the canal alignment has been moved as far as possible to the north to increase the irrigated area and also to reduce the submergence area in India . The faulty layout of the canal system has already started to result in widespread flooding inside Nepalese territory despite the fact that it is still not fully operational.

The Himalayan Times has very recently reported a sad news on September 2, 2006 “ Rapti changes course, spurs mass migration”. It is further reported “ Flood-hit residents of Holiya VDC’s Chauferi village are migrating to Uchuwa in Betahani’s Jhora jungle some eight kilometers west of their ancestral land following soil erosion caused by the Rapti River which has also changed its course.”

It is unfortunate to note that one of the main causes of the submergence of the Western Terai is our reckless disregard for the safety of our local inhabitants while pushing ahead plans to implement major storage dam projects. Nepal has embarked on a plan to launch three major storage dam projects in Western Nepal completely disregarding how the vast quantity of regulated water is going to be utilized in India. The feasibility study report of the Karnali Project carried out at an enormous cost provides in depth information on downstream uses, but we are not interested to look into them. Our concern is only electricity.

The Tip of The Iceberg

Last year it had been reported in one of the local English dailies dated July 21, 2005 on clarification of the Indian Embassy what is causing recent flooding in Banke district. “The Embassy reiterates that Laxmanpur Barrage, which is located 8 kilometers downstream of the India-Nepal border, is not yet operational, and the gates are never lowered and remain open at all times. There is, therefore, no question of Laxmanpur Barrage obstructing the flow of water in the Rapti River” It was further stated “ The Embassy understands that heavy rains in recent days had led to water logging in this region, including in adjoining areas in India…” It is clear based on the reporting of the Indian Embassy that the present widespread excessive flooding in Banke district could be primarily due to narrowing of the Rapti River course after the construction of the upstream guide bund which is an integral part of the Laxmanpur Barrage. Thus the present Banke district flooding problem might be only the tip of the iceberg. A vast area of the Banke district would remain all the time submerged during the wet seasons as soon as the Laxmanpur Barrage would be operational. It is explained hereinafter that the construction of Laxmanpur Barrage is an essential part of an overall plan to utilize the regulated flow of the Karnali and the West Seti rivers for irrigation in India. Thus this plan would be dependant on Nepal ’s decision to implement the Karnali or the West Seti Storage dam projects. Nepal must conduct through study to convince India to amend the design of the Saryu Canal if we want to resolve the Western Terai submersion problem.

High Level Saryu Canal

The Girjapur barrage across the Karnali river is located 1.2 km downstream of the confluence of the channel Girwa and Kauriala and 8.8 km downstream of Katarnia Ghat railway station of North Eastern Railway in India. The site of the barrage is about 16 km from the Nepal border along the River Kaurila.

There are two irrigation canals taking off from the Girjapur Barrage . On the left is the Saryu Canal running to the east beyond the Banganga River and on the right is the Link Canal connected with the Lower Sarda Barrage planned to irrigate about 2 million ha of lands. At present only the right bank canal is operational because the dry season flow of the Karnali River is insufficient for both the canals and there are technical difficulties to utilize the monsoon flow of this river. The year round operation of the Saryu Canal depends entirely on availability of the regulated flow from the proposed storage reservoirs in Nepal. The construction of the Saryu Canal, that started a long time ago, is still continuing at a snail's pace perhaps due to uncertainty about the date when the West Seti Project would be ready for operation. Nevertheless, it appears that the Saryu Canal could be made operational at short notice after the completion of the West Seti Storage Project because most of the structures of the Saryu Canal might be already ready. After that our people near the border area would be forced to live virtually in swamps throughout the year.

The Saryu Canal Project consists of a canal network that connects the head regulators of the barrages across the Saryu (Babai River) , West Rapti and Rohini ( Banganga River). A link channel 48.4 km long taking off from the left bank of the Girjapur Barrage outfalls into the Saryu River just upstream of the barrage across it. Similarly a link canal 56 km long taking off from the left bank of the Saryu River outfalls into the West Rapti River just upstream of the Laxmanpur Barrage. Beyond that a 125 km long canal taking off from the left bank of the West Rapti River extends right up to the Banganga River.

How the Submersion is Caused

The total length of the Saryu canal running almost parallel to Indo-Nepal border is about 230 km. In the original design the barrage across the Saryu river was at a location about 328 meters to the south of the railway bridge at Nanpara. Later, the design was modified and the location of the barrage was shifted 10 km to the north from the original site. Now the location of the Saryu Barrage might be only about 10 km downstream from the Indo-Nepal border. The longitudinal gradient of the Saryu canal has been reduced to a minimum. It is only one meter on a stretch of 9 km. The adoption of such extremely mild slope permitted the alignment of the canal to be pushed as far as possible to the north very close to Indo-Nepal border specially in its middle and lower reaches. This year’s severe Babai flooding in Bardia district also might have been triggered bypoundage from the Saryu Barrage built in India .

A Lake Instead of Siphons

Normally siphons are provided to deliver canal water across a river. A much higher average slope of the canal is required for the operation of this type of cross drainage structure, which has to operate under pressurized condition. A free flow hydraulic regime needs to be maintained at the river crossing if the average gradient of the canal is to be reduced. For reducing the average slope of the Saryu canal an altogether a different type of structures has been devised. Barrages have been built across the rivers to elevate the river water to such a level that would allow free passage of canal water across the river into the canal taking off from the other side of the river The contentious Laxmanpur barrage is one of such structures devised to deliver the water from the Girjapur barrage across the West Rapti river..

It would be necessary to maintain all the time pond water upstream of the barrage above certain fixed level to keep the Saryu canal running at desired capacity. Thus the pond would always be full, with the result that a sizeable area of lands in Nepalese territory could remain perpetually submerged. When the river is in flood, the water would be spreading out onto the lands that were never before regarded prone to flooding.

The Saryu canal is expected to cross innumerable small rivers and drains on its way. Embankments and dikes are needed to train these drains and small rivers for the protection of the Saryu canal. These river training structures could also result in widespread flooding inside Nepal where the canal route is close to the border.

Similar High Level Kosi Canal

India had proposed Nepal to build a canal similar to the Saryu canal to deliver Kosi water drawn near Chatra to irrigate lands as far as Birjung in the west. Instead of such Indian proposal, Nepal indicated its decision to implement the Sun-Kosi diversion project. The Indian proposal was dropped. The following is the excerpt from the Indian proposal.

“The Project, therefore, envisages the construction of a new barrage at Chatra which would be 8 km downstream of the proposed Kosi High Dam, with two high level canals, one on each bank in Nepal. These canals are expected to serve one of the most fertile areas of the terrain in Nepal. Preliminary assessment on the basis of data available shows that it may be possible to cover a gross command of 11.05 lakh ha on the right bank and 4.17 lakh ha on the left bank ( both in Nepal and India). Another major advantage of providing Kosi waters to the high level canals in Nepal would be that, dependence on smaller rivers which are crossed by these canals would not be necessary and it may be possible to develop these rivers in an integrated manner along with Kosi water which would provide irrigation needs both in Nepal and India and at the same time release waters below Chatra for intensifying irrigation in India.”

Media and Public Awareness

At present we are about to take final decision to grant permission to a private developer to build the West Seti Storage Dam Project to generate electricity completely disregarding the fact that the regulated flow of the West Seti River would play havoc in the Western Terai to the east of the Karnali River. Our media can play very important role in generating awareness of the danger to local people if the Pancheshwor, Karnali or West Seti water resources projects are implemented without resolving the Western Terai Submersion problems.

India is very much interested to avail itself of the opportunity to use regulated flow of our rivers. Nepal could use further progress in implementation of storage dam projects within our country as a strong bargaining chip to dissuade India from realizing the projects such as the Laxmanpur Barrage, Saryu Canal etc that threaten the life and property of a large number of Nepalese people.

In Conclusion

A through study should be carried out based on confirmed data to determine exactly the adverse impact of the Saryu Canal on Nepalese territory. It would also be necessary to determine how far to the south the Saryu Canal must be shifted once it is established that the proximity of the Saryu Canal alignment to the border is the cause of the present flooding in Nepal. It might be desirable to involve renowned water related institutions such as the Delft , Grinoble to help us to conduct the proposed studies.

Nepal should not commit a blunder by sticking to the decision to implement the West Seti Project before resolving the present flood problems in the Western Terai.

(Dr. Thapa writes on water resources)