The puzzle of solar lift irrigation in Nepal’s mid-hills

By Shisher Shrestha, Nilhari Neupane, Ritavrat Joshi, and Manohara Khadka

The mid-hills of Nepal account for 68% of the country’s total area^[1] and 56% of its arable land. Ranging in altitude from 610m to 4,876m, there are many small pockets of micro-irrigation that have the potential for high-value crop cultivation. However, almost a third of irrigable land here remains rainfed^[2] and studies indicate an increase in fallow land due to a lack of year-round irrigation infrastructure and decrease in agricultural workforce. A recent census found that several mid-hill districts have experienced negative population growth over the past decade, largely due to water scarcity, poverty, economic migration, and food insecurity.

Nepal receives around 80% of its precipitation during the June to September monsoon. Consequently, farmers who do not have reliable irrigation access experience water scarcity for more than eight months in a year. The situation is exacerbated as traditional water sources, such as springs and rivers, are drying up because of climate change, while precipitation variability is increasing, making the monsoon wetter and the dry season drier.

The need for lift irrigation

Settlements in the mid-hills are typically located on the top of the hills, while water supplies are in deep valleys, necessitating lift irrigation solutions. Energy insecurity therefore further worsens water access for irrigation. The urgent need for investments to improve water and food security and income generation makes a compelling case for investigating solutions through a water–energy–food–ecosystems nexus lens.

Fossil fuel-based pumping systems are impractical in remote mid-hill communities because of the need to haul fuel uphill. Road access is limited here, and some regions are inaccessible during and in the months after the monsoon. In addition to greenhouse gas emissions and other environmental issues, the diesel pumps typically used in Nepal are often low-head (8–28 meters) and high-discharge (550 liters/minute) pumps that are unsuitable for high-head projects. Electric pumps are suitable for regions that have high quality three-phase electricity, but in more remote mid-hill areas, grid connections are typically single-phase, unstable, and have power quality issues. Overhauling state infrastructure to improve reliability could take decades.

Decentralized solar lift irrigation (SLI) could provide year-round irrigation in mid-hill fields and improve water security by lifting water from lower-lying rivers. Solar energy is abundant, with average radiation of 3.6 to 6.2 kWh/m²/day and over 300 sunny days per year. Moreover, the correlation between water demand and solar energy potential in this region is high, meaning SLI could provide water during the dry months when demand is at its peak, building climate resilience and increasing food production into the dry season.

Stocktake of SLI projects

Under the CGIAR Initiative on NEXUS Gains, the International Water Management Institute (IWMI) carried out a stocktake of the status of SLI in Nepal through a literature review, primary and secondary data collection, and case study analysis. Although several SLI projects have been piloted under federal, provincial, and local governments with support from development partners and the private sector, very little literature about them exists. SLI is a mature and proven technology, but it faces institutional, social, governance, and economic hurdles. This stocktake aimed to explore whether SLI can deliver year-round irrigation to Nepal’s mid-hill communities.

Focus group discussions and key informant interviews took place in December 2022 as a basis for the case studies at seven SLI sites in Surkhet District. Six of the sites were funded by the Bheri Babai Diversion Multipurpose Project; one (Taranga SLI) received local government funding.

Three sites have been operational for the past three years and each household at these sites received a 10,000-liter water tank which farmers are permitted to fill once every 10 days. The farmers viewed the system favorably because it provided secure year-round irrigation, allowing them to cultivate multiple crops (off-season paddy, maize, wheat, and barley) and transition to high-value crops (vegetables, sesame seeds, etc.). They also received training in the operation and management (O&M) of SLI. The user communities collect a tariff of NPR 400 (~USD 3) per tank fill, of which NPR 250 (~USD 1.90) is paid to the operator; the remainder goes to a community fund to cover O&M costs. If farmers fill each tank once a month on average, the community will collect USD 2,400–3,300 over three years.

The remaining four sites were non-functioning. Geruwani SLI was operational for two years before its pump broke due to a blockage. Although the user community had collected a monthly tariff of NPR 100 (~USD 0.75) per household for water use, this was insufficient to purchase a replacement pump. The pump at Chepang SLI operated for about a week before being damaged due to a dry run. Although the system is not in operation, the community is required to pay NPR 12,000 (~USD 90) annually to lease the land where the panels are installed. At Taranga SLI, the system’s water intake was damaged due to improper design considerations of monsoon river flow. Its user community is working with the local government to fund the rehabilitation of the project. The community at Hattikhal SLI had requested the installation of an electricity-based irrigation system. The project implementer pushed for SLI, however, and the community refused ownership. This resulted in vandalism and damaged solar panels.

With the exception of Geruwani, communities from the non-functioning sites were unable to determine the tariff because the systems ceased to function during the first few weeks of commissioning. In these four communities, perception of SLI technology is, unsurprisingly, unfavorable and they are dependent on the project implementers for repair and maintenance costs.

Learnings

SLI holds lots of promise to reduce energy and water scarcity and provide year-round irrigation. However, securing high initial capital investment and establishing financial mechanisms for O&M and replacing and/or repairing key components remain key challenges. Improper design, poor implementation, and lack of user community engagement and ownership can severely hamper uptake and scalability. Capacity building and the availability of local technicians are also crucial. As most mid-hill farmers are smallholders, SLI is typically developed as a community project, and social dimensions can affect its success or failure.

The functioning sites have not encountered major O&M issues, making it difficult to predict how the user communities might cope with the need to replace expensive equipment. But over three years, they have amassed a sizable fund that has improved their preparedness.

A further potential benefit is the surplus energy often generated by SLI projects. This could be harnessed for productive and domestic use, and when the grid reaches these areas, it could be possible for farmers to sell excess energy to the grid, thus generating further income for O&M.

Much additional research is needed to generate evidence of the impact of SLI in Nepal’s mid-hills. To assess scalability, more work is required to identify viable business models, including ties between SLI projects and the irrigated agricultural value chain, and high-value, highly nutritious off-season crops and orchards suited to the microclimatic conditions.

^[1] National Planning Commission, Government of Nepal (2014). The Thirteenth Plan (Fiscal Year 2070/71 – 2072/73).

^[2] Department of Water Resources and Irrigation, Government of Nepal. Irrigation Master Plan 2019.

Shisher Shrestha is a National Researcher – Renewable Energy, Water and Climate Change at IWMI; Dr Nilhari Neupane is a Researcher – Development Economist and Quantitative Analysis at IWMI; Ritavrat Joshi is a Senior Program Officer at MinErgy; and Dr Manohara Khadka is Country Representative at IWMI and NEXUS Gains Lead for the Ganges Basin.

This work was carried out under the CGIAR Initiative on NEXUS Gains, which is grateful for the support of CGIAR Trust Fund contributors: staging.cgiar.org/funders

Header image: SLI project in Surkhet District, Karnal Province. Photo by MinErgy.