Exploring River ‘Memory’ Under a Changing Hydrological Regime Improving Mapping of Perennial and Non-Perennial Streams Based on Simple Flow/No Flow Observations

Dr. Kristin Jaeger, a research hydrologist with the U.S. Geological Survey, will discuss the modeling approach, how predictions in streamflow permanence are being applied to water resource questions and applications, and the effort to build collective databases of streamflow permanence observations.

Improving Mapping of Perennial and Non-Perennial Streams Based on Simple Flow/No Flow Observations

Abstract: Questions about when, where, and for how long water flows in streams are fundamental to understanding water availability and water quality. Identifying the location and hydroperiod of flow/no-flow conditions, collectively referred to here as flow permanence, remains a knowledge gap throughout the United States, particularly for lower order headwater streams, which comprise the vast majority of channel length within stream networks. Empirical models that use simple observations of surface water presence or absence and spatially gridded environmental data have shown promise in predicting if a stream location will have year-round flow and have been employed at regional (e.g., multiple U.S. states) and smaller subregional scales. The use of simple field observations represents a departure from conventional time-series streamflow data at USGS gages that are temporally rich (e.g. high accuracy 15-minute data) but are limited to only a few locations in catchments that tend to be perennial. To that end, in partnership with the U.S. Forest Service, the USGS has developed a mobile-application field survey to facilitate the rapid, standardized collection of qualitative flow/no flow observations that can be archived in a publicly available database. This presentation will highlight the modeling approach, how predictions in streamflow permanence are being applied to water resource questions and  applications, and the effort to build collective databases of streamflow permanence observations.

Biography: Dr. Kristin Jaeger is a research hydrologist with the U.S. Geological Survey since 2015. She holds a B.A. in biology from Colorado College, M.S. in forest hydrology from the University of Washington, Ph.D. in fluvial geomorphology from Colorado State University and was an assistant professor at Ohio State University prior to USGS. Her research is focused on understanding and predicting where and when streams flow or go dry using physical and empirical models. In addition, she conducts research in mountain streams and rivers to understand geomorphic response to drivers of climate, floods, fire, and human related activities of timber harvest and mining.

Exploring river ‘memory’ under a changing hydrological regime

Abstract: Natural flow regimes are highly variable over time with periods of low, inter-flood flow interspersed with flood events of variable magnitudes, durations and sequencing. Historically inter-flood periods have been disregarded from investigations as it has been thought that the stability of non-cohesive beds could only be altered by above threshold flows capable of sediment transport. However, this is at odds with recent river ‘memory’ data which provides evidence to suggest that entrainment thresholds in subsequent flood events and the rate and composition of bedload flux are strongly related to the inter -flood duration. Similarly, as well as being related to inter-flood duration entrainment thresholds and bedload flux characteristics in the subsequent flood events also appear related to the characteristics of the flood wave itself.   Using results from flume experiments, this presentation will explore the concept of river ‘memory’ by looking at the magnitude of bed stability responses to variations in both inter-flood duration and hydrograph duration and unsteadiness. 

Biography: Dr. Annie Ockelford is the stakeholder and engagement lead within the Flood Hydrology Improvements Programme of the UK Environment Agency and a visiting research fellow at the University of Hull, UK.  She holds a BSc in geography from the University of Southampton and a PhD in civil engineering from the University of Glasgow.  Prior to moving to the Environment Agency, she was a principal lecturer in physical geography at the University of Brighton, UK. Her research is focused on understanding how ‘river memory’ effects river stability in relation to inter flood duration and hydrograph characteristics. She also researches the controls on microplastic flux through fluvial systems.  

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