Authors of the new book Rivers for Life joined a Wilson Center audience to discuss how the disruption of natural river flows by large dams and river diversions is causing a worldwide crisis in river health and the loss of valuable ecosystem services. While water quality and sanitation issues have been at the forefront of the global freshwater policy discussion for the past two years, little attention has been shown to the issue of ecosystem services—watershed ecosystems provide services including the provision of water supplies, flood mitigation, soil fertility maintenance, provision of food, and recreational opportunities among many others. While acknowledging the grave crisis caused by a lack of drinking water and sanitation on human health, Postel and Richter related that this book is an attempt to provide a 21st century approach to river and watershed management and water allocation for policymakers and scientists and to educate the general public on the equally grave crisis facing plant and animal species, including humans, that depend on watershed ecosystems. "Total human impact on rivers has increased nine times since 1950," warned Postel. At least 20 percent of the earth's 10,000 freshwater fish species are at risk of extinction or are already extinct.
"In order to meet the needs of both people and ecosystems, we need a fundamental shift in our thinking of water management. We call this new mindset the sustainability boundary," said Postel. Richter explained further, "It is not just about minimum [river] flows, it is a much more complicated matter." He continued by explaining that rivers follow a natural pattern of gradations of flows, including flooding, normal flow, and low flows. Plant and animal species depend on these natural gradations for increased food supply and reproductive cues among other things. When these flows are disrupted by dam or river diversions, plant and animal populations become vulnerable, some even driven to extinction.
The sustainability boundary approach would mitigate these impacts by allocating water in a new way. In this approach, scientists and policymakers would define the quantity and timing of flows needed to support freshwater ecosystem health, and then establish a sustainability boundary that protects these flows from human use and modification. Human uses could increase over time, but only up to the sustainability boundary. New water demands would be met through conservation, improvements in water productivity, and reallocation of water among users.
Postel and Richter continued by highlighting three watersheds as case studies with varying levels of success in sustainable water use. These case studies demonstrate strategies for policymakers and communities to adopt in meeting water needs for people and nature. Strategies include greater governmental responsibility for water planning, rethinking how dams are managed to allow for more natural patterns of water release, and greater collaboration among national and state-level water planners.
Audience members expressed concern that by setting a specific amount of water for ecosystem services, could both encourage unnecessary water use up to that level in the present as well as set a target that could be difficult to raise in the future, if it were determined that not enough water was set aside for ecosystem services. Postel and Richter acknowledged this weakness, and said that a target would need to be flexible enough to be changed in the future if scientific evidence demonstrated that the ecosystem needed more water. Institutions, they said, play a key role in providing this kind of flexibility, but the authors acknowledged that this will be a major challenge in implementing a 21st century approach to water management.
Drafted by Jennifer Kaczor.