Multipurpose Kankai Project

By DR. AB THAPA

The Kankai River originates in the Mahabharata range. It flows down meandering but generally heading south in the Mahabharata and Siwalik ranges Several other tributaries also merge before it debouches into the Terai plain. After a run of about 75 km from its mouth where this river originates, it passes through the site of the intake barrage built some years back under the Asian Development Bank financial assistance. The river bed elevation of the place where the Kankai River enters from the mountain area into the Terai plain is around 120 m. After a run of about 25 km on the Terai plain it crosses the Indo-Nepal border where the river bed elevation drops down to only 73 m. In India, the Kankai River flows down further southwards and finally joins the Ganges River.

The Kankai is a medium size river. The drainage area of this river is 1,189 sq. km at the weir site of the Kankai Irrigation Project, and 1,546 sq. km. at the Indo-Nepal border. . The upper region of the Kankai basin is mountainous but the lower region is flat land of the Terai plain. Thus, the upper region of the drainage basin possesses good potential for the generation of hydropower whereas the lower region is suitable for irrigated agriculture. The rainfall is over 2,000 mm in the mountainous area, and more than 2,200 mm on the Terai plain. The average annual flow of the Kankai River from January 1965 to December 1969 was 1,700 million cubic m in terms of total volume or 54 cubic m./ sec in terms of rate of flow.

Multipurpose Kankai Project

The Kankai Multipurpose Project is regarded as one of the most important projects for the development of Eastern Nepal. There are several obvious advantages in implementing this project in near future. This project can help to meet the demand for electricity in Eastern Nepal. The hydropower station of this project can be planned to generate electricity to match in a best possible way against the true demand for electricity in the eastern region. A vast area of lands in Jhapa district on both sides of the Kankai River would be brought under year round irrigation which could help to double the present cropping intensity. There is a big danger of the Kankai River floods to the people living on both sides of this river. The floodplain of the Kankai River is too big despite the fact that it is relatively a small river by comparison with the rivers like the Karnali and Gandak. A significant proportion of the Kankai River floodplain could be reclaimed and converted into good agricultural lands after the full implementation of the Kankai River development plan..

Involvement of Asian Development Bank

Government’s attention was drawn as early as the 1960s to exploit the potential of the Kankai River. Department of Electricity was the first to conduct preliminary study of this river for power generation. The Asian Development Bank’s growing interest in providing financial assistance to Nepal gave fresh impetus to develop the potential of the Kankai River. The Bank agreed that they would be prepared to finance for the time being a small proportion of the irrigation component of the Kankai development project. Following the Asian Development Bank’s advise our government requested the Bank for technical assistance to conduct the detailed study of the Kankai Irrigation Project. The Bank approved the request and the studies on the Project commenced in January 1971. The feasibility study was completed in September 1971. After completing various formalities the Bank decided to finance the Kankai Irrigation Project. The construction of this project commenced from around the middle of 1970s.

German Government Assistance

As soon as the construction of the Kankai Irrigation Project started our government made a request to the German Government to provide assistance to implement the power component of the Kankai Project. It was necessary to build a high dam to implement the power component of the Kankai Project. German Technical Mission sent to Nepal to examine our government’s request found that it would not be feasible to implement the Kankai high dam project exclusively for power generation. As a result, it was decided to conduct feasibility study of the Kankai Multipurpose Project to utilize the potential of this river for the generation of electricity and also irrigation to cover much of the Jhapa district. The feasibility study was completed in the year 1978.

Components of Multipurpose Project

Irrigation development was identified to be the primary component of the Kankai Multipurpose Project. The prospect for agriculture development in Jhapa district is quite promising. Under the project development planning a net area of 67,450 ha would be irrigated by a gravity irrigation system. The net irrigation area of 67,450 ha comprises 8,000 ha of the existing Kankai Irrigation Project, and 59,450 ha to be developed under the Kankai Multipurpose Project (KMP). The storage reservoir of the KMP will provide sufficient water to provide year round irrigation. The present cropping intensity of 119% is estimated to increase to 197% after the implementation of the KMP. The main crop proposed is paddy, out of such paddy crop about 50% will be early paddy and the remaining 50% monsoon paddy. Wheat will take about 14% of the cropped area, followed by jute with 10%. Other crops such as the maize, pulses and mustard have also been suggested.

The water resources of the Kankai River will allow the construction of a power plant with an installed capacity of 38 MW which will generate 194 GWh electricity per annum. The capacity of the power station could be raised to about 90 MW if this project is to be planned to operate only about 6 hours every day to meet the growing demand for peaking energy. For this type of operation further additional studies would be required to provide one or more small ponds to re-regulate the water discharged from the hydropower station of the KMP.

Flood Control

At present the low lying river valley of the Kankai is subjected to annual flooding. About one third of the land lying between the Kankai and Biring rivers has already been made unfit for agriculture by erosion of the top-soil and subsequent silting. The Kankai River is attacking at several locations on the right bank also and, as a result, vast area of fertile lands are laid waste. Thus, the flooding severely constrains economic use of lands and agricultural development in vast areas along the banks of the Kankai River. The flood control benefit to be accrued from the construction of the Kankai high dam is expected be relatively high.

Annual Kankai floods are far more severe in India than in the upper regions of this river lying in Nepal. Thus, the KMP would provide significant flood control benefit to India also.

The Kankai High Dam

The most important component of the Kankai Multipurpose Project is the high dam. It is proposed to build the high dam at a location approximately 3.8 km upstream of the East-West highway bridge. The dam would be 85 m high above the valley bottom. The crest elevation will be 205 m above the MSL. The crest length will be 340 m. The dam would be gravel-sand type with asphaltic concrete lining.

The total storage volume of the Kankai reservoir would be 1,480 million cu. m. The volume of the reservoir is quite big by comparison with the annual flow ( 1,700 million cu. m). As a result, it would be possible to completely shutdown the hydropower station and store the water during the monsoon and other periods when the electricity supply in the grid is in surplus to the demand and there is no need of water for irrigation. The conserved water could be used during the dry season when the water becomes scarce and its demand for the generation of electricity and irrigation greatly increases.

Project Cost and Benefits

According to the estimate of the Kankai Multipurpose Project feasibility study report submitted in 1978 the total project cost is expected to be about 160 million US $. Out of it the cost of the dam and power facilities will be 66 million US $ and 24 million US $ respectively. The rest of the estimated amount will be spent on irrigation development.

After the full development, according to 1978 estimate, the Kankai Multipurpose Project is expected to generate every year about 38 million US $. Out of it the power benefit would be about 8 million US $. The Kankai Multipurpose Project can be planned to generate mostly firm power to meet the peaking demand for electricity. The total power benefit can be expected to be much higher because the value of the peaking energy is much higher by comparison with the base load energy.

Nepal Prevented to Implement the Project

German Government had pledged to provide substantial proportion of the project cost as outright grant. The Asian Development Bank was given the task to conduct technical appraisal of the project on behalf of prospective donors.

The Asian Development Bank mission was about to arrive in Kathmandu within the next few days to appraise the Kankai Multipurpose Project. Suddenly events took a dramatic turn at the very last moment. Some legal experts in the ADB raised water right issue. The departure of the ADB mission to appraise the Kankai Multipurpose Project was postponed indefinitely. Resolution of this problem was not sighted in near future. As a result, Nepal decided to request the German Government to transfer the funds pledged for implementing the Kankai Multipurpose Project to Marshyangdi Hydroelectric Project.

(Dr. Thapa writes on water resources)