Measures to safeguard and restore river connectivity

Abstract

Freshwater connectivity and the associated flow regime are critical components of the health of freshwater ecosystems. When freshwater ecosystems are fragmented, the movements and flows of species, nutrients, sediments, and water are altered, changing the natural dynamics of freshwater ecosystems. The consequences of these changes include declines and loss of freshwater species populations and freshwater ecosystems, and alterations in the delivery of certain ecosystem services, such as fisheries, buffering of flood events, healthy deltas, recreational and cultural values, and others. Measures exist that can maintain and restore connectivity or mitigate against its loss in the face of constructed barriers or other habitat alterations. These measures include system-scale planning for energy and water resources that includes options for limiting loss of freshwater connectivity; putting in place protections for keeping critically important freshwater habitats connected; mitigating impacts on freshwater ecosystems via barrier design, fish passage, or implementation of environmental flows; and restoring freshwaters via barrier removal and reconnection of rivers, wetlands, and floodplains and via active management of groundwater recharge. We present case studies of measures applied in Europe, Asia, Africa, and the Americas and reflect on the next generation of innovation needed to further enhance and advance the implementation of restoration and protection and the mitigation of freshwater connectivity impacts.