Study how the geomorphology of the Salt River channel has changed over the last 100 years and how factors such as the damming of the Salt and Verde Rivers and gravel mining operations have contributed to these changes.

For more than 1,000 years there has been a city on the banks of the Salt and Gila Rivers in the vicinity of what is now Phoenix. The course of natural processes as embodied by the river have interacted with the course of human events as evidenced by the city, each exerting influence on the other. The myriad of tangled connections between the natural and social systems has inevitably altered each of them, so that understanding of one without understanding of the other is incomplete. Within the last 100 years, intensive technological development of the river resources, its space, water, materials, and biotic complements, has radically altered the natural processes and forms of the river. At the same time, the river has influenced development of the city, sometimes as a resource such as recreational space, and sometimes as a hazard such as flooding. This constantly changing fluvial system, integrating natural and artificial influences, is the foundation for the primary riparian ecosystems of the region.

The research questions of this project are: (1) What has been the nature of change in the geomorphic/riparian system, and how have human and natural factors controlled the distribution and intensity of the change over the past century? (2) Why does the river have its present geomorphic/riparian configuration, and how stable is that arrangement from geomorphic, hydrologic, and geographic perspectives? and (3) How does the river respond to ongoing changes in the spatial arrangement of human activities and attending technological impacts?

This project promises improved understanding of the dynamics of dryland rivers, especially how and why they change under the influence of urban development. The research also promises to provide an integrating factor in the CAP LTER effort, because the river integrates the influences of hydrologic, geomorphic, biotic, and human technological systems. The research will provide a repeatable quantitative approach to assessing the changes in the river and as it continues its millennium-long connection between natural and social systems.