Experimental flooding to restore a dammed river in the Grand Canyon

American rivers have been reshaped by thousands of dams which have altered their hydrology, ecology, and sediment transport regimes. At the same time, these dams provide flood control, water supplies, and energy to human communities. Managing dammed rivers is a balancing act that requires weighing competing values against one another in an effort to reach an optimal scenario. Such scenarios are being tested at the Grand Canyon National Park, where massive floods can be safely and experimentally conducted. These experiments have advanced our understanding of river management and highlight the role national parks have played in the history of science.