Annualmeeting:2017 CSDMS meeting-119


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Evaluating Luminescence as a Sediment Transport Metric

Harrison Gray, University of Colorado - Boulder Boulder Colorado, United States.

[[Image:|300px|right|link=File:]]The role of climate change on landscapes is one of the most difficult remaining challenges in geomorphology. It is thought that climate primarily modifies landscapes through sediment production and transport in rivers. However, collecting the data needed to resolve the relationship between climate and sediment transport has remained elusive. This issue stems from a lack of a methodology that can work in a wide variety of river environments. Furthermore, this problem is made pressing by a need to understand the coming effects of human-induced climate change.

To address this problem, I developed a model to capture sediment transport using luminescence, a property of matter normally used to date sediment deposition. Luminescence is generated via exposure to background ionizing radiation and is removed by exposure to sunlight. This behaviour is sensitive to sediment transport and could potentially be used to infer sediment transport parameters. I derive the model by performing a simultaneous conservation of sediment mass and absorbed radiative energy expressed as luminescence. The derivation results in two differential equations that predict the luminescence at any point in a river channel network. The model includes two key sediment transport parameters, the sediment transport velocity and the storage-center exchange rate. From these parameters, other key sediment transport variables such as the characteristic transport length-scale and the sediment virtual velocity can be calculated. These parameters can be constrained by determining the model’s luminescence parameters through field measurement and lab experiments.

I test my model against luminescence measurements made in rivers where these sediment transport parameters are well known. I find that the model can reproduce the observed patterns of luminescence in channel sediment and the parameters from the best-fit model runs reproduce the known sediment transport parameters within uncertainty. The success of the model, and the advent of new technology to measure luminescence using portable devices, suggests that it may now be feasible to collect critical sediment transport data cheaply and rapidly. This method can now be used to test outstanding hypotheses of the influence of climate on sediment transport.