Developing Countries Tap Future Water Availability

Eastern Threat Center scientists expand WaSSI tool

Rivers are full of sediments in rural areas in Rwanda due to soil erosion from farming. Photo by Ge Sun.
Rivers are full of sediments in rural areas in Rwanda due to soil erosion from farming. Photo by Ge Sun.

Developing countries often face extreme challenges that negatively affect forests that provide local water supplies. Africa alone has roughly 22 percent forests and woodlands, areas rich with biodiversity, timber, and water resources. However, many of these areas face extreme conditions that threaten unprotected forests and ultimately future water availability.

In 2005, Eastern Forest Environmental Threat Assessment Center researchers collaboratively created the Water Supply Stress Index (WaSSI) model. WaSSI predicts how climate, land use, and human population changes may impact forests’ ability to provide ecosystem services such as water supply, carbon sequestration, recreation, and wildlife habitat.

Eastern Threat Center researchers continue to expand WaSSI, most recently focused on enhancing user experience in east Africa. The updated online WaSSI tool features: 1) English and Spanish user guides; 2) geographically relevant maps in user-friendly formats; and 3) expanded climate and land use change options, information, and future scenarios for the east African countries Rwanda and Burundi.  

“Deforestation and climate change pose significant threats to water resources in the populous Rwanda region in spite of ongoing international conservation efforts,” says Ge Sun, Eastern Threat Center research hydrologist and lead WaSSI developer. “Expanding the model’s capabilities in developing countries helps refine conservation strategies in areas responding to population growth, extreme weather, and other human influences impacting water resources.”

African land managers are encouraged not to cut trees because of potential impacts on drinking water, household services, and water used to irrigate rice and tea farms and other agricultural-based practices. “People need to make informed decisions about water supply and use,” says Sun. “WaSSI helps land managers run ‘what if’ scenarios, identify areas of concern, and use available resources more responsibly. It’s important that forests are recognized and valued beyond just tourism and recreation.”

Water availability is important to current and future land management planning and human well-being. Natural resource managers use WaSSI to visualize the effects of management options on ecosystem productivity, making informed water supply-related decisions for short- and long-term strategies to sustain ecosystem services.

WaSSI is a collaborative effort among federal agencies, universities, and non-governmental organizations. The multi-disciplinary WaSSI development team has conducted workshops in Mexico and Africa and continues to improve the tool’s application throughout the United States.

For more information, email Ge Sun at or Erika Cohen at

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