The National Irrigation Master Plan (NIMP) has been formulated and recently elaborated in order to increase food production and self-sufficiency. Cropping patterns and corresponding irrigation water demands have also been addressed.
The NIMP has also identified new irrigation areas in all the districts concerned. The estimated expenditure is 1.35 million for 91 acres which accounts to about Nu. 95,000 per acre. An assessment report shows that 71% of the existing canals have abundant or adequate water supply while 29% have inadequate water supply. The Integrated Water and Resource Management specialist confirmed that the availability of water is not a constraint for developing new irrigation areas.
The use of water in Bhutan is streamlined mainly to agriculture and hydropower. The team behind trhe NIMP has also investigated the potential competition between irrigation water demand and hydropower generation. But according to specialists “Irrigation water demand is competing with water use for hydropower generation, not the other way round.”
Hydropower generation is considered as a non-consumptive water use as water is only used to drive the turbines and then flows back to the river, so hydropower generation does not actually consume water, by contrast, irrigated agriculture does consume water by evaporation, transpiration and the irrigation water is generally tapped from the higher order tributaries. Therefore irrigation water demand affects hydropower.
Even with the 11th FYP aiming to triple the installed capacity to 4,500 MW by 2018 it is not a major issue according to Robert Roostee if competition for water should be taken into account in the national policies towards food self-sufficiency and power generation.
The Draft National Irrigation Master Plan was presented during the National Environmental Commission consultation workshop for the Integrated Water Resource Management.
The expected start of NIMP would be either 2016 or 2017.
The need for an elaborate national irrigation plan is being seen as essential to counter the impact of climate change. Extreme river discharges and scarcity of water are expected to occur if the present scenario is un-mitigated. This calls for a new design criteria for water works and an adequate “room for rivers” to avoid flooding as mentioned in the National Irrigation Master Plan.
Agriculture in Bhutan is mostly subsistence farming which is the biggest consumer of water by way of irrigation. Since most fields are fragmented and scattered along the hill slopes, water is tapped from springs and streams. Although there are some larger irrigation schemes in the southern foothills, providing an advanced or alternative for tapping water in most of the cultivated land in other parts of Bhutan is generally expensive due to the landscape and geography.