EAR-PF: The scaling properties of river-lake networks

Gardner John R, Durham NC

Investigators

Abstract

This post-doctoral fellowship awarded to Dr. John Gardner and carried out at the University of North Carolina will examine how properties of lakes and river-lake networks affect sediment patterns in inland waters.Rivers are generally thought of as linear veins transporting sediment and water from mountains to oceans across continents. Lakes are often conceived as closed systems. However, most lakes have a river outlet or inlet and are part of the river network. Too much sediment in rivers and lakes may be a pollutant, while too little sediment in rivers may cause destructive erosion of riverbanks and starve coastal communities of sediment needed to maintain elevation and ecosystems. Understanding river-lake networks as systems and suspended sediment concentration (SSC) lake footprints at the continental scale will advance our knowledge of hydrologic scaling laws; how rivers are shaped; and how water, sediment and materials are transported from continental interiors to coastal oceans. Understanding the structure and scaling properties of river-lake networks, lake footprints in river networks, and how natural and artificial lakes differ in their controls on sediment transport requires a data-intensive approach that combines geospatial, remote sensing, and in-situ data across the entire continental United States. Relationships for scaling the number, size, and spacing of in-network lakes with river size will be derived, and lake footprints and proxies for sediment trapping efficiency will be estimated using remote-sensing data calibrated with in-situ suspended SSC data. Lake footprints include the recovery of SSC downstream of lakes and the attenuation of SSC above and within lakes. Web applications and visualization tools will merge satellite and field observations of inland waters to help connect people to their local watersheds. End users will be able to explore the structure of river-lake networks in their watershed to increase awareness of river-lake connectivity; integrate satellite data into education and research; and conceptually merge rivers and lakes. Sediment content of rivers and lakes will be shared with water resource scientists and managers, and the public. This research will advance of our understanding of U.S. watersheds in three main areas: 1) the development of a physical template for river-lake network models and analytical expressions of lake distribution within river networks; 2) identification of the type, size, and location of lakes that impact river geomorphology; and 3) signatures of anthropogenic impacts on sediment transport in rivers networks by comparing natural and artificial lakes. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.