WEAP: Water Evaluation and Adaptation Planning

WEAP In Action

Explore real-world projects powered by WEAP

California, USA

Balancing Water Use in California's Central Valley

Forecasting Water Rights Allocation Environmental Flows

SEI worked with the California State Water Resources Control Board and Stantec to develop SacWAM, a WEAP model that represents the Sacramento River Basin and Sacramento-San Joaquin Delta. SacWAM is helping decision-makers assess potential regulatory revisions, weighing trade-offs between protecting ecosystems, securing urban supplies, and sustaining agriculture.

Chile

Advancing Integrated Watershed Planning in Chile

Groundwater Modeling MODFLOW Drought

In 2019, Chile's General Water Directorate (DGA) launched a national effort to prepare Strategic Water Plans (PEGHs) in all river basins, requiring integrated modeling of both surface and groundwater to address drought and other climate extremes. As of 2022, 39 PEGHs are informed with WEAP models, 29 of which are linked with MODFLOW in a unified modeling framework, including the five pilot basins—Copiapó, Limarí, Choapa, Petorca, and Ligua—from the initial study.

Quito, Ecuador

Building Urban Water Resilience in Quito

Ecological Flows Climate Vulnerability Extreme Events (Seismic) Páramo Ecosystems

Through the DAR AGUA Quito project, SEI supported the EPMAPS water utility in strengthening its Master Water Plan under future uncertainty. A daily WEAP model simulated hydrology, seismic hazards (volcanic eruptions and earthquakes), and climate impacts. Adaptation management options, such as reducing water losses, expanding infrastructure, and conserving páramo wetlands, were visualized in a Tableau dashboard, enabling decision-makers to test strategies for a resilient water supply.

Amu Darya & Syr Darya River Basins

Linking Water and Energy in Central Asia

Adaptation Water-Energy-Economy Nexus Climate Resilience Hydropower

Since 2020, SEI has partnered with USAID and the World Bank to connect water, energy, and economic planning in Central Asia. By integrating WEAP with the LEAP energy model and AMES economic model, governments are able to explore co-benefits and trade-offs of mitigation and adaptation actions. Early findings revealed that billions of dollars in investments could be misallocated without this cross-sector perspective, including missing out on an additional 20% of storage in dry years.

California, USA

Reconciling Aquatic Habitat and Supply in California's Santa Clara Valley

Fisheries Reservoir Operations Aquatic Habitat Assessment

SEI applied WEAP and the Aquatic Habitat Assessment (AHA) plugin to quantify tradeoffs of salmon and steelhead habitat alongside water supply reliability. The results were used by a range of conflicting parties to design and build consensus around the set of reservoir reoperations, which were certified under the final environmental impact report in 2023. The AHA plugin quantifies the surface area and suitability of habitat for the different life stages based on river conditions.

Senegal River

Measuring Water Stress with WEAP (SDG 6.4.2)

Adaptation Sustainable Development Water Stress Indicators

A new WEAP plugin developed with the UN Food and Agriculture Organization (FAO) calculates water stress at the catchment scale, supporting monitoring of Sustainable Development Goal (SDG) Indicator 6.4.2. This tool provides countries with detailed insights on water scarcity, helping them evaluate risks, prioritize adaptation actions, and track progress toward securing clean water and sanitation for all under a changing climate.

“

The most important gain is I think the improvement of collective knowledge, understanding of water resource uses, infrastructure, management and allocation today. WEAP now offers us the opportunity to concretely experience the effects of climate change on the Durance river and to test adaptation levers. In order to collectively make the best decisions and guide public policies.

Pascal Dumoulin Syndicat Mixte d'Aménagement de la Vallée de la Durance (SMAVD) France

WEAP has become a key tool to develop my research and I also include it in my teaching as a very user friendly tool to understand the dependencies between water resources systems components.

Dr. Andrea Momblanch Benavent Cranfield Water Science Institute, Faculty of Engineering and Applied Sciences United Kingdom

I've seen WEAP be most effective in a recent effort by Valley Water to evaluate proposed reservoir operating rules in three main watersheds in our area that are intended to mainly benefit anadromous fish in in our local streams while balancing our water supply needs.

Eric Olson Santa Clara Valley Water District USA

WEAP has been immensely useful in meeting the mission of the California Water Plan. Having an integrated, physics-based, high-level model that can reliably calculate important change factors has allowed us to efficiently examine future conditions.

Paul Shipman California Department of Water Resources, Division of Planning USA

”

Highlights

Discover the core features that make WEAP a powerful tool for water resources planning and decision support

Integrated Approach to Water Resources Planning
Unique approach for conducting integrated water resources planning assessments.

Stakeholder Engagement for Inclusive Decision Making
Transparent structure facilitates engagement of diverse stakeholders in an open process.

Water Balance Models for Resource Allocation
A database maintains water demand and supply information to drive mass balance model on a link-node architecture.

Simulation-Based Modeling of Water Systems
Calculates water demand, supply, runoff, infiltration, crop requirements, flows, and storage, and pollution generation, treatment, discharge and instream water quality under varying hydrologic and policy scenarios.

Scenario Analysis for Policy and Planning
Evaluates a full range of water development and management options, and takes account of multiple and competing uses of water systems.

User-Friendly, GIS-Based Interface
Graphical drag-and-drop GIS-based interface with flexible model output as maps, charts and tables.

Model Integration with External Tools
Dynamic links to other models and software, such as QUAL2K, MODFLOW, MODPATH, PEST, Excel and GAMS.

Historical and Projected Databases
Includes built-in global databases of past land use and climate records, as well as CMIP-based climate scenarios.

Automatic River and Catchment Delineation
Generates river networks and watershed boundaries automatically from digital elevation data, streamlining model setup and ensuring consistency across scales.

WEAP