This project developed the basis to predict the behavior of water, sediments, nutrients, pathogens, and organic matter in rivers, floodplains, and hill slopes. This involved developing new mathematics for 'anomalous' transport processes - which represents types of motion not described by previously developed theory. Using this new information, prior observations from rivers and watersheds were integrated to better understand the main factors that control interactions between water, sediments, and dissolved and suspended material. The results revealed that the behavior of soils and sediments can be described in a much more unified way than believed previously. There is an essential similarity between the motion of soils on hillslopes, landslides, underwater mudflows, and sediment transport in rivers, with transitions between each type of behavior. Nutrients, pathogens, and organic matter are delivered into the upper layer of sediment beds, where they are mixed, buried, and slowly resuspended. Slow transport into and out of sediment beds limits the biogeochemical transformation of nutrients and organic matter. Further, alternating periods of transport, deposition, mixing, and remobilization cause particles to be buried progressively deeper over time, leading to long-term retention. In cases where there are ongoing inputs of pathogens or contaminants, these materials will accumulate in sediment beds in rivers and other freshwater systems, leading to long-term colonization or contamination of the sediments. This information on the behavior of freshwater systems, the measurement methods and advanced mathematics developed in the project, and the associated computer models will improve assessment of risks of problems such as erosion, land destabilization, nutrient pollution, ecosystem degradation, and waterborne disease transmission. The advances made in this project will also support development of strategies for sediment stabilization and watershed conservation and restoration to protect built infrastructure, human health, and aquatic ecosystems.

Project investigators convened workshops to transmit findings to earth and environmental scientists, and worked directly with US governmental programs and international programs to inform aquatic system assessments, ecosystem conservation strategies, and public health protection efforts. Education programs introduced thousands of American youth (elemetary school through high school) to key concepts on water, watersheds, land stability, and aquatic ecosystems.

Last Modified: 10/28/2018
Modified by: Aaron Packman