Date: Thursday, September 7
Time: 3:30 pm - 5:00 pm
Location: 410 John D. Tickle Building
In intensively managed landscapes, changes in the land cover from what were previously grasslands, and their associated management practices, have led to a high degree of spatial heterogeneity and temporal variability in landscape processes that were absent pre-settlement. This has fundamentally altered terrestrial and instream sediment flux characteristics in regards to net amounts and proportions of source contributions, at shorter time scales. Water and sediment flux laws are now highly impacted by event-based dynamics. Whereas some events result in highly intermittent fluxes, others result in fluxes that largely propagate in the form of waves. This behavior is governed by the extent of land cover at the given time of the season, as well as the magnitude of the storm event. In addition, flux behavior changes as one moves from the plot scale to the watershed scale. Thus, fluxes are now non-stationary due to continued human activity and its co-play with climate. The goal of this study is to develop a better understanding of the non-stationarity in water and sediment flux laws that arise from the co-play between land use and climate. Our approach involves the development of a modeling framework that considers all the exchanges between terrestrial and instream sources and addresses the issue of equifinality regarding terrestrial and instream source contributions on net fluxes. The modeling framework couples an established terrestrial erosion model with an established in-stream sediment transport model. As a first step, our study focuses on the Clear Creek Watershed, IA, which is part of the Critical Zone Observatory for Intensively Managed Landscapes. We complement our modeling efforts with extensive terrestrial and instream field observations gathered at different times of the growing season. Findings from this study will shed light on the dominant factors governing fluxes laws and how they change over the course of a season, as well as the factors that control the changes in the flux laws across space.