event 13 Mar 2020

Publication // Integrated modelling of the impacts of hydropower projects on the water-food-energy nexus in a transboundary Himalayan river basin

By Amjath-Babu, T. S., Sharma, B., Brouwer, R., Rasul, G., Wahid, S. M., Neupane, N., ... & Sieber, S. (2019). This paper looks at hydropower development in the transboundary Koshi river basin in the Himalayan region and aims to give possible benefits of the projects proposed.

Himal nexus

The sustainable development goals (SDGs) and the Paris agreement target a global cleaner energy transition with wider adaptation, poverty reduction and climate resilience benefits. Hydropower development in the transboundary Koshi river basin in the Himalayan region presents an intervention that can support the SDGs whilst meeting the regional commitments to the Paris agreement. This study aims to quantify the benefits of proposed water resource development projects in the transboundary basin (4 storage and 7 run-of-the-river hydropower dams) in terms of hydroelectric power generation, crop production and flood damage reduction. A hydro-economic model is constructed by soft coupling hydrological and crop growth simulation models to an economic optimization model. The model assesses the potential of the interventions to break the vicious cycle of poverty and water, food, and energy insecurity.

In South Asia, 281 million people are undernourished, 362 million people have no access to electricity and at least 600 million depend on biomass for cooking. Within this region, the highly populated (10% of the world population) Ganges–Brahmaputra–Meghna (GBM) transboundary (that spans China, Nepal, India and Bangladesh) basin that has highest concentration of rural poor (with limited access to energy, food and clean drinking water ) in any given region of the world, while having largely untapped hydropower (eg: 42 GW in Nepal) deserves particular attention.

Although the Ganges basin has enormous potential for multipurpose reservoirs and run of the river (ROR) projects (especially in Nepal), it ironically suffers from energy scarcity and inadequate irrigation facilities. Ganges sub-basins like the Koshi present a developmental conundrum as they tend to be underdeveloped with high levels of poverty and acute energy scarcity, despite their rich natural endowment with fertile soils and abundant water resources. Given the current largely unmet needs of power, irrigation, and flood regulation that hinder regional development, there is substantial scope for using WRD projects as engines for low carbon growth and climate resilient rural development utilizing the energy-water-food nexus. Previous research identified 11 high potential WRD projects in the Koshi river basin, of which 4 are storage and the remainder run-of-the-river (ROR) dams.

The performance of the identified WRD projects depends on factors such as river flow, water management rules, and upstream and downstream water use. A basin-scale analysis is therefore essential for integrated water resources management. In order to assess the basin-wide economic benefits of the WRD projects and their sustainability in the light of future climate change, a coupled hydro-economic model is developed, paying special attention to the economic value of the storage space and irrigation capacity that can be created by surface and groundwater using hydroelectric power from the proposed set of dam projects in the Koshi basin and the stability of these benefits under future climate change.

Key messages

The results of the integrated hydro-economic model, combining the WEAP and DSSAT model in an economic optimization procedure show that the expected benefits from the proposed multipurpose WRD projects in one of the poorest regions in South Asia can be significant in terms of generated electricity and enhanced agricultural production at the basin scale.

The possible basin-wide flood protection benefits through the creation of aquifer storage, identified in a recent World Bank study for the Ganges basin were also quantified in this study, but appear to be limited, and highly dependent on the available technology to use groundwater aquifers to store floodwater. The estimated benefits under the baseline scenario of USD 2.3 billion gross per year outweigh the estimated annual costs of USD 0.68 billion for the 11 hydropower projects. Even if the investment costs would be twice as high as estimated to account for cost overruns (or vice versa, if the benefits would only be half of what they are expected to be based on this study), the benefits from the 11 projects would still outweigh their costs, generating a net benefit of USD 0.9 billion per year (or USD 0.5 billion if the benefits would be 50% less than estimated here). These results are robust when accounting for future climate change. The results highlight the fact that the development of hydropower in the Koshi basin can support the mitigation and adaptation goals of the Paris agreement and achieve the SDGs within the basin.

Finally, the findings reported here have important policy implications for achieving water, food and energy security, as well as mitigating the impacts of climate change. Benefits derived from hydropower, irrigation and flood moderation can serve as a catalyst for economic and social development, and help to achieve a number of the Sustainable Development Goals, including ending hunger, alleviating poverty and providing increased access to water and energy services as well as support the goals of the Paris agreement. However, the development of the proposed projects will critically depend on building mutual trust and favourable regional cooperation between India and Nepal.


April 2019


© The authors.


Amjath-Babu, T. S., Sharma, B., Brouwer, R., Rasul, G., Wahid, S. M., Neupane, N., ... & Sieber, S. (2019). Integrated modelling of the impacts of hydropower projects on the water-food-energy nexus in a transboundary Himalayan river basin.

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