Modeling spatial and temporal variability of sediment balance across a southern California watershed
Presentation Type
Oral Presentation
Abstract/Artist Statement
The focus of river restoration and management has shifted from local, site-specific projects to more holistic watershed-scale management. Consequently, tools that help to provide an understanding of river systems as a whole are necessary for managers. Of particular importance for river management is the concept of sediment balance: the balance between the supply of sediment from the surrounding watershed to the river system, and the ability of the river’s flow regime to transport that sediment. Alteration of either of these components by modification of the river or its surrounding watershed can lead to sediment surplus or sediment deficit, both of which can change the shape and function of a river. River floodplains play an important role in sediment balance, and various mechanisms allow rivers to store sediment, or recruit sediment from floodplains. Existing frameworks for quantifying sediment balance conditions and sediment movement through watersheds are generally applied to large areas and do not provide significant mechanistic information regarding channel-floodplain sediment exchange and transport. Others are detailed numerical models that do provide this information, but require extensive calibration of parameters that are difficult to measure, and can only be applied at individual reach scales. A need exists for a modeling framework that provides some mechanistic information, but can be generalized and readily applied to broader spatial extents. To address this gap, I developed a model that is driven by spatial data that represents actual conditions in real rivers. The model simulates the evolution of sediment balance conditions resulting from flow events in a watershed, accounting for various types of disturbance such as dams, wildfires and impacts from land uses such as agriculture. It also accounts for channel-floodplain sediment exchange, using proxies for mechanisms that are easily obtained from widely available datasets (e.g. digital elevation models). To visualize how sediment balance conditions propagate through river systems in response to flow events, the model can simulate either real (based on river gage data) or hypothetical floods. The model was calibrated using field data collected at various sites in the Santa Clara River (SCR) watershed of Southern California. It was then applied to the SCR to simulate how a flood event during February of 2017 affected sediment balance conditions. This model can serve as a valuable tool in planning and implementing river restoration projects by providing contextual information on specific project sites. By accounting for connectivity and propagation of disturbance throughout the basin, potential impacts to restoration projects and sites can be accounted for, and predictions made about how river structure may change through time.
Mentor Name
Andrew Wilcox
Modeling spatial and temporal variability of sediment balance across a southern California watershed
UC 330
The focus of river restoration and management has shifted from local, site-specific projects to more holistic watershed-scale management. Consequently, tools that help to provide an understanding of river systems as a whole are necessary for managers. Of particular importance for river management is the concept of sediment balance: the balance between the supply of sediment from the surrounding watershed to the river system, and the ability of the river’s flow regime to transport that sediment. Alteration of either of these components by modification of the river or its surrounding watershed can lead to sediment surplus or sediment deficit, both of which can change the shape and function of a river. River floodplains play an important role in sediment balance, and various mechanisms allow rivers to store sediment, or recruit sediment from floodplains. Existing frameworks for quantifying sediment balance conditions and sediment movement through watersheds are generally applied to large areas and do not provide significant mechanistic information regarding channel-floodplain sediment exchange and transport. Others are detailed numerical models that do provide this information, but require extensive calibration of parameters that are difficult to measure, and can only be applied at individual reach scales. A need exists for a modeling framework that provides some mechanistic information, but can be generalized and readily applied to broader spatial extents. To address this gap, I developed a model that is driven by spatial data that represents actual conditions in real rivers. The model simulates the evolution of sediment balance conditions resulting from flow events in a watershed, accounting for various types of disturbance such as dams, wildfires and impacts from land uses such as agriculture. It also accounts for channel-floodplain sediment exchange, using proxies for mechanisms that are easily obtained from widely available datasets (e.g. digital elevation models). To visualize how sediment balance conditions propagate through river systems in response to flow events, the model can simulate either real (based on river gage data) or hypothetical floods. The model was calibrated using field data collected at various sites in the Santa Clara River (SCR) watershed of Southern California. It was then applied to the SCR to simulate how a flood event during February of 2017 affected sediment balance conditions. This model can serve as a valuable tool in planning and implementing river restoration projects by providing contextual information on specific project sites. By accounting for connectivity and propagation of disturbance throughout the basin, potential impacts to restoration projects and sites can be accounted for, and predictions made about how river structure may change through time.