Accounting for Uncertainty in Regional Flow-Ecology Relationships

Flow-ecology relationships are critical for developing and adaptively managing environmental flows. However, uncertainty often arises from data limitations and an incomplete understanding of the spatial and temporal attributes inherent to each relationship. Accounting for sources of uncertainty is critical given mounting interest to implement environmental flows at large scales, often with limited information. We used the South Fork Eel River watershed in northern California, USA, as a case study to quantify data gaps and uncertainty in flow-ecology relationships. Through a rigorous literature review, we found that few flow-ecology relationships related explicitly to the flow regime and none completely spanned the hydrologic or geomorphic variability exhibited across the watershed. Identified data gaps informed several sensitivity analyses within a Bayesian Network model which showed that the modeled ecological outcome differs by up to 50% depending on the type and magnitude of uncertainty. This study presents a general framework for quantifying spatial and temporal data gaps that can be applied to other regions and information types to improve the understanding of flow-ecology attributes and representation of uncertainty.