
Water and energy are closely interlinked and interdependent. Energy generation and transmission requires utilization of water resources, particularly for hydroelectric, nuclear, and thermal energy sources. Conversely, about 8% of the global energy generation is used for pumping, treating and transporting water to various consumers.
Efforts to address climate change have heightened awareness of these linkages – the “water-energy nexus” – and of the need to integrate water and energy planning and decision-making, especially in areas facing water scarcity.
Climate, water and energy are intricately linked, so choices in any one sector can often reverberate across the others. To achieve the best possible outcomes, policy-makers need to understand cross-sector interactions and tradeoffs – the so-called “nexus”. This requires new tools for integrated analysis.
Seeking to meet this need, SEI has linked its water and energy decision support systems, which are already used in policy-making and planning around the world: the Water Evaluation and Planning (WEAP) system, and the Long-range Energy Alternatives Planning (LEAP) system. The integrated tools allow users to model evolving conditions in both water and energy systems and examine cross-sectoral impacts of different policy choices.
To find out more about how the integrated WEAP and LEAP tools can be used to explore issues and tradeoffs at the water-energy nexus, browse our archive of articles, case studies and policy briefs:
- SEI is undertaking integrated water-energy-food analyses in several countries to help decision-makers understand cross-sectoral impacts and synergies for different development options.
- How could an integrated perspective help countries in the Middle East find more effective approaches to climate-smart development, mitigation and adaptation?
- SEI links powerful water, energy and climate change mitigation planning software tools to help policy-makers grapple with ‘nexus’
- Video: David Purkey discusses the WEAP and LEAP tools

- Integrating the WEAP and LEAP systems to support planning and analysis at the water-energy nexus
- How SEI has linked its powerful water and energy/mitigation planning software systems for integrated analysis and decision-making.
- Using WEAP and LEAP systems to explore issues and tradeoffs at the water-energy nexus with the example looking at the potential impacts of desalination in California.
- Afghanistan development planning: How a large-scale scenario exercise using WEAP could help decision-makers find the best way to allocate limited water resources