The objective of MR-2733 is to predict the waves, currents, and sediment transport at underwater munitions remediation sites. The estimates of the near-bottom environmental conditions will constrain probabilistic predictions of munitions exposure, burial, and migration. Cartographic visualizations of the probability of munitions mobility resulting from the coupled simulations will provide remediation site managers with integrated and cost-effective tools for risk assessment and decision-making.

The technical approach in this project consists of three primary steps: (1) generating ensemble hydro- and morphodynamic simulations of the three-dimensional model, Delft3D; (2) coupling Delft3D simulations with a probabilistic munitions mobility model; (3) producing cartographic visualizations of munitions mobility. Delft3D includes a system of coupled models (wave, circulation, and sediment transport) to simulate hydrodynamic flow and resulting morphologic change. Model boundary conditions will be generated from real-time or historical observations, global/regional model results, and their uncertainties. The ensembles of hydro- and morphodynamic simulations combined with a filtering method will produce accurate and probabilistic representations of the spatially and temporally varying environmental conditions at remediation sites. The near-bottom probabilistic predictions of bottom velocity and local sediment transport will be used as input to a probabilistic model for munitions mobility (MR-2645), producing high-fidelity predictions of munitions exposure and mobility. Prototype cartographic visualizations of the probability of munitions mobility and environmental conditions for both climatological (long time-scale) and time-dependent (short time-scale) forcing will be produced from the coupled model results. In the first half of the project, we will apply the coupled modeling system at the US Army Corps of Engineers Field Research Facility (FRF), in Duck, NC. The FRF is the prototype site for the near-field munitions mobility model, has the most extensive record of environmental conditions (in situ and remotely sensed) of any nearshore location in the world, and has existing observations of munitions mobility for model testing. In the second half of the project, researchers will focus on relocating the model framework to an underwater munitions remediation site.

Accurate estimates of munitions mobility will lead to more cost-effective characterization, planning, and use of available resources. A primary benefit of the effort will be to provide probabilistic information that site managers can use to make informed decisions about munitions response activities. To aid in the transfer of model results to site managers, results from MR-2733 will be compatible with risk assessment tools developed within SERDP. Scientifically, this research will improve the capability to estimate model uncertainty in hydrodynamic and morphologic simulations by adapting a hybrid deterministic-probabilistic modeling approach for the nearshore environment. This work will also improve forcing inputs to nearshore munitions models, resulting in a better understanding of the role of time-dependence. MR-2733 will provide prototype inputs to decision tools, which can lead to ESTCP demonstration and transition to operations.