Unexploded Ordnance Devices (UXO) and Discarded Military Munitions (DMM) are found in many coastal regions. They are especially present in US coastal waters that coincide with former shooting ranges and cause a potential risk to personnel. These objects are constantly exposed to environmental influences such as saltwater, which causes corrosion, waves and currents as well as mobile seabed sediments. Thus, the management and risk assessment of the numerous objects is a big challenge. For site managers, the location of the objects, along with their type and condition, are of particular interest. Even if these information were known from surveys, the locations of particular objects may vary due to continuous environmental influences. Thus, at the least, a permanent monitoring is needed. This project aims to quantify the influence of currents and waves on the mobilization and migration of any objects, in particular with regard to migrating bedforms. This also includes analysis of the (self-)burial and re-exposure of objects. Ultimately, the critical conditions for mobilization are to be identified, along with a probability of occurrence for considered areas of interest and how far objects subsequently migrate. This will allow for continuous and more consistent monitoring, significantly reducing the need for repeated and expensive surveys.
An analysis of the mobilization and migration of UXO and DMM will be based on existing mobilization models, which thus far consider the critical current and wave conditions, respectively, for the mobilization of certain objects on stationary sand beds. These models will initially be adapted for use on US sites and corresponding objects of interest. This will include the incorporation of wave and current data, as well as the local bathymetry and various objectrelated parameters, which will be determined via wind tunnel experiments, computational fluid dynamics and the boundary element method. Thus far though, these models do not allow for migrating bedforms. In order to better understand the underlying effects of such bedforms, numerical simulations using the lattice Boltzmann method will be run. These will consider sediment transport in the flow, the effects of surface waves, erosion and sedimentation processes and, if necessary, soil liquefaction and bedload transport. Furthermore, the burial and re-exposure of objects due to such migrating bedforms will be investigated. The results will then be used toward improving the existing mobilization models. These will ultimately include additional physical effects which are relevant for the migration of objects. Finally, the models and experimental data are to be compared and cross-validated with further existing mobilization models and relevant experimental data, thus providing a realistic margin of applicability.
The enhanced and adapted models for the current- and wave-induced mobilization of UXO and DMM will be able to deliver individual return time maps for the required areas and objects of interest as well as the critical environmental conditions for the mobilization of the objects. Furthermore, the extended models will ultimately combine all project results and thus take current- and wave-induced mobilization, the (self-)burial and re-exposure of objects, migrating bedforms and consequently also the migration direction and speed of objects into account. The results will be realized as a bundle of software tools, which will help site-managers reduce survey costs and provide them with a decision support tool, which can directly be used in practice. In addition, it is to be expected that the novel and detailed analysis of the considered effects will result in several peer-reviewed journal articles.