ONE-DIMENSIONAL SOLUTE TRANSPORT MODELS: PARAMETER UNCERTAINTY IMPLICATIONS FOR QUANTIFYING BIOGEOCHEMICAL CYCLING IN STREAM NETWORKS
There has been a large body of work in recent years to better understand the underlying assumptions in parameter identifiability of the OTIS model, and the implications for solute transport studies. This study seeks to further this understanding by applying the OTIS model to tracer data from field studies performed on streams of varying size and discharge values (0.02-2.00 m3/s) on Alaska’s North Slope, in Oregon, and in Montana. Using a modified OTIS framework, which provides for parameter optimization and further Monte-Carlo based global sensitivity analyses, “best fit” parameters, as well as uncertainty bounds for model parameters, can be determined. The main goal of this work is to understand how parameter uncertainty translates into our interpretation of storage metrics, including storage residence times. The range of storage metrics as calculated from the range of viable parameters can indicate the applicability of transport models in remediation studies.
The results of this study will help to inform scientists and engineers alike of the potential error ranges in storage metrics in relation to the transport model outputs.