Two river diversion projects are currently underway in the country
--BY RAJENDRA PRASAD ADHIKARI
Of the 225 billion cubic metres of surface water obtained yearly from the monsoon rain and snow melt, less than 10% are in productive utilisation within the country’s boundary. Remaining flow as floods, inundating lowlands of Tarai before entering the Indian territory. The meagre utilisation of the country’s water resources in agricultural and hydropower sectors is mainly attributed to the country’s rugged topography which makes the water resources extraction project expensive. Recent advancements in river water transformation technology by digging tunnels through geographical barriers like hills have not only helped take water flow to a desirable elevation for power generation but also helped to divert water to the drought-affected areas, despite their colossal cost.
After the successful completion of diversion of water from Bheri river in Surkhet to Babai river of Banke through a 12.2-kilometre tunnel, a similar project is under execution along BP Highway in Sindhuli and Ramechap districts - about 120 kilometres south-east of Kathmandu. The project will divert a part of the Sunkoshi river water flow (77 cubic metres per second) to Marin river in Kusumtar of Kamalamai Municipality through a 13.3-kilometre tunnel across the Chure hill. After flowing for nearly 10 kilometres, the water reaches Bagmati Irrigation Barrage to augment year round irrigation service to 122,000 hectares of arable land covering five districts of Madhesh Province - Bara, Rauthut, Siraha, Sarlahi, and Saptari.
Apart from agricultural use, these two river diversion projects also generate hydropower owing to the steep tunnel slope - 46 MW and 28.62 MW, respectively, from Bheri-Babai and Sunkoshi-Marin projects.
Unlike the conventional drill and blast tunnelling methods that took a considerable time for the 28-kilometre Melamchi tunnel to divert drinking water to Kathmandu valley, technically advanced machine has been utilised for tunnel digging works in both Sunkoshi-Marin and Bheri- Babai river diversion projects. Despite the cumbersome task of transporting a tunnel boring machine (TBM) from the factory to the construction site and the high upfront cost, the simplicity and steady tunnel boring and simultaneously supporting tunnel wall with precast concrete segments as the tunnel deepens further is a state-of-the-art dexterous performance of the mechanised tunnelling work.
The TMB basically comprises a rotating drum with a circular disc at the front mounted with metal cutters of various types and sizes followed by a thrust system and trailing support mechanism. The sequential performance of TBM involves the following steps: the disc cutter exerts compressive stress against the encountered rocks to fracture; the cracking rock chips from the tunnel face called the muck are transported outside the tunnel by means of a conveyor to the muck car to depose suitably; the rear part of the machine erects concrete segments to support excavated tunnel walls; and the thrust cylinder of the machine either supporting against the concrete segments or the firm rock of the tunnel pushes the entire set up further ahead to continuously repeat its job. The entry of the machine from one end and its exit from the other end signifies the completion of the tunnel. The pace of performance was nearly 700 metres to a kilometre a month in the recently accomplished Bheri-Babai water diversion tunnel.
Both the river water diversion schemes - both designated as national pride projects - are costlier projects compared to conventional tunnel approach. The Sunkoshi-Marin project aims at irrigating 150,000 hectares of land in drought-prone Madhesh Pradesh while also generating 28.62 MW of hydro electricity with the total cost estimates of Rs 83.51 billion. The per MW cost is estimated at a whopping Rs 1.61 billion. The project is made viable with the multiple use of water in non-consumptive hydropower and consumptive irrigation under the assumption that the entire agricultural area of 150,000 remains productive with highly extensive seasonal cropping .The cost incurred in the project can thus be recovered by selling these products in the local market at prevailing cost.
In the present context of skyrocketing trade deficit, especially in daily consuming agricultural produce with India, extensive agriculture farming in the Madhesh Province by using diverted irrigation water from the snow-fed Sunkoshi river looks highly lucrative in achieving project report perceived 17.7% Economic Internal Rate of Return (EIRR). However, it is to be noted with caution that despite being an agricultural driven economy and yearly colossal budgetary investment to enhance productivity yield, it is quite disheartening to know that Nepali kitchen has been regularly run by the imported commodities. We have been buying daily consumable food items such as rice and lintels, vegetables and fruits, including dairy and animal products spending remitted foreign currencies hard-earned by our youth in foreign land. Once a rice exporting country, the agricultural productivity in Nepal has now deteriorated to such a level that the central bank has to curtail imports in order to accumulate foreign currency reserves to ensure food security for the Nepali people. Further, the vast stretch of agricultural land, which would see massive cultivation of rice and wheat a couple of decades back, has now been turned into fragmented land strips in the name of urbanisation and settlement extension. It would be no wonder that by the time these expensive water diversion tunnel projects start delivering water to the designated agricultural land within the scope of the projects, the ever-extending and unregulated urbanisation would turn agricultural land into a concrete jungle .
It is quite relevant to cite some exemplary cases here. Chitwan , once a government-focused district for irrigated agriculture development with the execution of highly expensive Narayani lift irrigation, Kahgeri and East Rapti irrigation projects, has turned into a settlement, leaving the irrigation water delivering infrastructure redundant. Irrigated areas are turning into urban settlements at a fast pace in Sunsari-Morang in the east and Mahakali in the west. The proposed agriculture development area with ground water extraction in Bhairahawa-Lumbini Ground Water Development Project, a project given high priority by the government and the World Bank, has only traces left for cultivation with urban settlement covering the majority of the area.
It is very wise to understand that the huge investment made in mega projects are economically justified based on the estimated future crop production capacity increment after water reaches the field for irrigation. If the stipulated land area as envisioned in cost benefit analysis of the project is not available due to rapid urbanisation, the expected outcome cannot be recovered precisely, thereby turning a once economically prosperous project to cost overburdened one. A regulatory policy coherence with all the three levels of governments has to be brought forward in order to get a long-term economic benefit from the agricultural area as envisioned in the economic analysis of the project. It not only helps the country recover the heavy cost incurred in the diversion projects, but also supports significantly in reducing agriculture trade deficit.
Once 150,000 hectares of land start getting irrigation facilities from Sunkoshi-Marin and 52,000 hectares from Bheri-Babai, we will have high crop production on one hand and various attributes of an agriculture-driven economy on the other hand. These include value additions on agricultural commodities such as storing inside modern warehouses, properly grading and packaging by using environment friendly biodegradable bags of different sizes and shapes, quality control in compliance with the international practices, and transporting to national and international markets. As all these activities demand manual and machine-oriented skills, Nepali youth can get dignified jobs in the country’s agro-industry. Land and water-based agriculture industries powered by locally produced hydroelectricity and run by the country’s youth to feed the Nepali population can be achieved, making agriculture an engine for the country’s economic growth.
(Adhikari is an engineer and served Nepal government in various high level capacities.)