WEAP for adaptation planning: Water and climate resilience

This briefing from the Stockholm Environment Institute (SEI) describes the Water Evaluation and Adaptation Planning (WEAP) platform, a scenario-based modelling tool designed to help decision-makers understand climate impacts on water systems and develop adaptation strategies. It highlights WEAP's role in supporting National Adaptation Plans (NAPs) and provides examples of its application in various global regions to manage water scarcity, resource allocation, and transboundary river basins.

• As of 30 September 2025, 73% of nationally determined contributions (NDCs) under the Paris Agreement included adaptation goals. Additionally, 67 countries have submitted national adaptation plans (NAPs), while another 77 are in the process of developing them.
• The Water Evaluation and Adaptation Planning (WEAP) platform is a scenario-based modelling tool with a 35-year history and over 50,000 users across 190 countries. It integrates supply- and demand-side perspectives to allow users to analyze the effects of climate change scenarios on water availability, the impact of resource allocation on the economy and ecosystem health, and the benefits of interventions such as flood protection, added storage, and efficiency measures.
• WEAP supports the development of National Adaptation Plans (NAPs) through several key features: using climate projections for temperature and precipitation to simulate groundwater levels, runoff, and water demand; comparing adaptation strategies like demand management and infrastructure upgrades; providing a stakeholder-driven interface for participatory planning; and integrating with macroeconomic and energy models to analyze the water-energy-food nexus.
• SEI has applied WEAP in diverse global contexts to support adaptation planning: in California at local, regional, and state levels; in Rwanda to project water supply and identify conflicts between uses; in Central Asia (Kazakhstan, the Kyrgyz Republic, Tajikistan, Turkmenistan, and Uzbekistan) for the Amu Darya and Syr Darya river basins; and in the Upper Lempa River Basin spanning El Salvador, Guatemala, and Honduras to address over-extraction and resource degradation.

APA

Davis, M., Huber-Lee, A., & Forni, L. (2025). WEAP for adaptation planning: Water and climate resilience. Stockholm Environment Institute. https://www.sei.org/wp-content/uploads/2025/11/weap-adaptation-planning-water-climate-resilience.pdf

Chicago

Davis, Marion, Annette Huber-Lee, and Laura Forni. WEAP for adaptation planning: Water and climate resilience. Stockholm Environment Institute, 2025. https://www.sei.org/wp-content/uploads/2025/11/weap-adaptation-planning-water-climate-resilience.pdf.

Wikipedia

{{cite report |last1=Davis |first1=Marion |last2=Huber-Lee |first2=Annette |last3=Forni |first3=Laura |title=WEAP for adaptation planning: Water and climate resilience |publisher=Stockholm Environment Institute |date=November 2025 |url=https://www.sei.org/wp-content/uploads/2025/11/weap-adaptation-planning-water-climate-resilience.pdf |access-date=17 August 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{davis2025weap, author = {Davis, Marion and Huber-Lee, Annette and Forni, Laura}, title = {{WEAP for adaptation planning: Water and climate resilience}}, institution = {Stockholm Environment Institute}, year = {2025}, month = nov, url = {https://www.sei.org/wp-content/uploads/2025/11/weap-adaptation-planning-water-climate-resilience.pdf}, urldate = {2026-08-17}, note = {Indexed by Climate Insights Directory} }