Bhutan has been working toward achieving economic self-reliance since the First Five-Year Plan and irrigation is a major component of achieving this goal. Given the limited cultivated area of less than three percent of the total land cover, effective utilization of arable land is the key to improving agricultural productivity. A field study for irrigation development for Bhutan in 2017 conducted by JICA pointed out some of the critical issues pertaining to irrigation development for Bhutan. This article reviews the findings reported by the field study and presented them here as the ‘critical challenges to be addressed for developing sustainable irrigation systems’ in the country.
Weak linkage between irrigation systems and agricultural development plans
Enhancing agriculture productivity through expansion of the irrigated area should also address the shortages of farm labour, enhance access and opportunities to market agricultural produce, and focus on developing relevant farming skills. The report also suggested improving those elements that directly affect agricultural productivity, such as the quality of seeds and soil management. The cause of the decline of the cultivated areas and the decreased unit yield of main cereals as well as reasons for the abandonment of terraced paddy fields was also found to be lacking. Investigating these underlying causes is critical for framing appropriate solutions. Research elsewhere has found that greater irrigation facilities coupled with crop diversification and necessary policy and institutional support resulted in higher agricultural productivity.
Poor feasibility study of the irrigation plans
The report also highlighted that ‘the target setting’ for the irrigation systems development for the Eleventh Five Year Plan was misguided, because the relevant agency first set the target for an irrigated area, and then selected the 108 irrigation systems to achieve the target. During the selection of the target irrigation systems, field surveys were not conducted for all the 108 irrigation systems. Additionally, neither technical feasibility nor economic efficiency of the expansion of the target irrigated area was confirmed before the implementation of irrigation projects. Background and historical data on topographic stability, water availability, reliability of water delivery, and the likelihood of landslide needs to precede the civil works. Conducting a comprehensive field assessment of the sustainability of water sources including catchments and springsheds characteristics in the context of climate change should become a critical part of a feasibility study. In order to boost the confidence in the feasibility of the project in the future, the GIS and GPS data of pre-survey and post-project could be stored and managed properly for future references and updates.
Limited hydro-meteorological data impairs irrigation facility designs
The report also highlighted the limited availability of geospatial and hydrogeological data in the country to properly design irrigation facilities. For example, the report found that the topographic map of Bhutan from the 1990s at a map scale of 1: 50,000 (around 25 m spatial resolution) was not suitable for irrigation planning, although it was used, for instance, for Yudhiri River irrigation planning. Further, the report pointed out that flood discharge is quite heavy in most of the streams/rivers resulting in river bed depression and riverbank erosion. Such geophysical and hydrological heterogeneity poses significant challenges to irrigation planning and irrigation facility design. The high degree of variation in local precipitation, hydrology, and changing climate further creates complex geophysical challenges to Bhutan’s irrigation development. The number of meteorological and river discharge observation stations as of 2017 was also deemed insufficient, because of the limited observation frequency. Without plans and programs to capture the long-term and high-frequency hydro-meteorological data, the target of the 12th Five Year Plan, ‘NKRA-17 – Climate-smart and disaster-resilient development programme aiming to explore alternative water sources to contribute to ensuring continuous drinking and irrigation water’ seems far-fetched. The irrigation development across the country should take a holistic approach to gather geospatial and hydrological data, identifying sensitive areas such as recharge areas, and studying the characteristics of local aquifers if we are to ensure the irrigation system delivers continuous water to agriculture fields. The use of large-scale maps, i.e., very high-resolution satellite and UAV imagery (1cm – 5 m), is recommended to properly design irrigation facilities. A recently signed MoU between Japan and The Royal Government of Bhutan for creating an improved topographic map of Bhutan is a welcoming sign of improving the quality of geospatial data in the country.
Limited feedback from failing irrigation systems
Numerous projects across the country are also targeted to renovate the dysfunctional irrigation systems. However, the JICA reports exclusively mentioned that there is limited record and understanding of the underlying causes of the dysfunction. These are basic management lapses that could be addressed with minimal financial implications while it would help to ensure that the new irrigation system would not become dysfunctional again for the same reason. The annual status of irrigation systems across the country as of 2017, is reported to be maintained by the Department of Agriculture, however, such feedback seems to have minimal influence on decision makings.
Limited knowledge on countermeasures for landslides
Many irrigation systems across Bhutan have the main canals often damaged by landslides. There is limited knowledge of countermeasures for landslides in Bhutan but the reports highlighted that some level of preventive maintenance could be undertaken, which was observed to have not been done. Instead, the report indicated that widespread use of low-quality construction materials further worsened the ability of the irrigation systems to sustain the natural pressure.
The limited capacity of community water user groups
Water User Associations (WUAs) were expected to manage the irrigation systems as the facilities are transferred to the WUAs after the completion of construction works. The need for improving post-construction management and enhancing the skills of such groups has been also identified by the JICA report. For instance, there were reported cases where the WUAs missed timely repair and maintenance, which later had to be repaired with huge financial implications. For example, the results of inefficient management of irrigation systems by WUA, limited check and balance among various user groups, and poor design are noticeable to everyone driving along the Radhi-Rangjung road where the irrigation canal overflows during monsoon, free channeling along the road.
Institutional and Management Issues
As of 2017, the limited human capacity in irrigation engineering was found at all levels of central, regional agricultural centers, and local governments. In many cases, the available experts often failed to create topographic maps, did limited water discharge measurements, decisions were often based only on the cropping pattern but not the cultivated area, and so forth. Such practices risk widening the overall project scope and finally failing the project – as in the case of the irrigation system in Samar gewog, Haa. In the design of irrigation facilities, the importance of considering the water flow, intake – delivering, and distribution as an integrated system, and the importance of waterproofing of hydraulic facilities were not appreciated adequately. Finally, the JICA report also mentions a lack of supervision during construction and low levels of collaboration among relevant agencies in working towards the national water resources development plan. Actually, the limited timely supervision was attributed to have led to the dysfunction of the irrigation system for Nakha-Mendi and Chankar-Jangtena chiwogs of Paro.
As a group of technical personnel, we propose relevant agencies engaging in the development of irrigation systems across the country approach irrigation systems in a holistic manner – linking to agriculture development, gathering hydro-meteorological data, and making informed decisions – based on a robust investigation of underlying reasons for dysfunctional irrigation systems.
The article is published based on personal experiences and observations by a group of water researchers from Bhutan.
The group can be contacted at email@example.com