Predicting Carp Egg Transport based on HDF outputs from HEC-RAS 2D

Abstract Submission: Understanding the dynamics of early life-stage outcomes of invasive carp eggs can shed light on new avenues to manage carp populations. Eggs are released by adults during fertilization and are transported downstream as they develop. One-dimensional models such as FluEgg are in use to simulate drift characteristics of invasive carp eggs in rivers characterized as a single channel (e.g., Illinois River Waterway) with the goal of predicting egg trajectory and survivability. However, many Nebraska rivers are characteristically shallow, braided systems which exhibit additional complexity. Therefore, we are developing a model for predicting egg drift in wide, shallow reaches of the Platte River and tributaries with similar characteristics. We selected HEC-RAS 2D for the hydrodynamic model because: (1) while a 3D-CFD model would be more rigorous, an accurate 3D model of a reasonably-sized study reach would be computationally expensive, (2) the reaches of interest are shallow and dominated by two-dimensional flow behavior, and (3) HEC-RAS 2D is widely used and has outputs that can be integrated into external software for Lagrangian tracking of individual eggs. HDF outputs produced by HEC-RAS 2D are directly loaded by QGIS Python scripts and used in an advection-diffusion model that utilizes the two-dimensional velocity field outputs to predict egg tracks; variations of individual egg tracks result from randomness of the turbulent diffusion. Ultimately, statistics of the Lagrangian egg tracks will be used to predict probabilistic distributions of dispersed eggs and their viability to mature into adults.

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