Short course on principles and applications of beach nourishment

Covers the engineering aspects of beach nourishment. (Document is 192 pages

Synthesis of current knowledge of the biophysical impacts of dredging and disposal on the Great Barrier Reef: report of an Independent Panel of Experts

[Extract] This report provides an independent synthesis of the current knowledge of the effects of dredging and sediment disposal on the physico-chemical environment and the biological values of the Great Barrier Reef World Heritage Area (World Heritage Area), as assessed by an Expert Panel. Dredging and sediment disposal can change the physical and chemical environment and affect the biological values of the World Heritage Area. Many of these effects will be context dependent and will differ between locations, types and extent of dredging and sediment disposal activities. The Expert Panel's evaluation identified the following key direct and indirect effects

Physical, biological and cultural factors influencing the formation, stabilisation and protection of archaeological deposits in U.K. coastal waters

A considerable corpus of information regarding the formation of terrestrial archaeological deposits exists which is not matched by studies of deposit formation in coastal waters. Similarly, there is a disjunction between strident calls for minimal disturbance investigation, with conservation in situ, and knowledge of how this might actually be achieved in the marine environment. The manner in which the investigation of deposit formation can complement the study of in situ conservation is considered An approach is proposed which combines selected elements of Schiffer's Transformation Theory with a method of studying changes to deposits outlined by Wildesen. It is suggested that, although sufficient regularities can be detected in the influence of formation processes to allow their influence to be recognised and inference refined accordingly, there are case specific limitations on the extent to which the precise influence of each process can be described and evaluated. A case study is presented which investigates casual depredation as a formation process. Commercial fishing activity and marine burrowing activity are the subject of detailed consideration. New insights into these processes result from this study and specific recommendations concerning in situ conservation of deposits subject to their influence are made. The need to consider fishing practice as well as the mechanical properties of fishing gear in the study of deposit formation and protection is emphasised. The excavation of a 16th century wreck in Studland Bay, Dorset, is used to demonstrate the pervasive influence of burrowing activity and the problems associated with mitigation of this process. Recommendations are made regarding future study of formation processes and the development of policy related to the management of the submerged archaeological resource

Perspective Review on Subsea Jet Trenching Technology and Modeling

This paper presents a comprehensive review on subsea jet trenching technology via a critical analysis of its principle, mechanism, devices, modeling approaches, as well as properties of subsea sediments. This review shows that the success of jet trenching operations is closely related to some key factors including the soil conditions, trencher specifications, and characteristics of pipelines or cables. Three case histories are presented to demonstrate the importance of these key factors and their interrelationships. This paper also points out a number of challenges pertaining to the implementation of the jet trenching method in carbonate sediments, as well as some limitations and gaps in the existing modeling approaches. Future perspective researches that are recommended to develop: (1) promising theories, like turbulent submerged flow, and (2) robust numerical approaches, such as the smoothed particle hydrodynamics (SPH) and material point method (MPM) to substantiate the experimental experience and reveal possible hidden mechanisms. Document type: Articl

UNDERSTANDING UNDERWATER PHOTOGRAMMETRY FOR MARITIME ARCHAEOLOGY THROUGH IMMERSIVE VIRTUAL REALITY

Underwater archaeological discoveries bring new challenges to the field, but such sites are more difficult to reach and, due to natural influences, they tend to deteriorate fast. Photogrammetry is one of the most powerful tools used for archaeological fieldwork. Photogrammetric techniques are used to document the state of the site in digital form for later analysis, without the risk of damaging any of the artefacts or the site itself. To achieve best possible results with the gathered data, divers should come prepared with the knowledge of measurements and photo capture methods. Archaeologists use this technology to record discovered arteacts or even the whole archaeological sites. Data gathering underwater brings several problems and limitations, so specific steps should be taken to get the best possible results, and divers should well be prepared before starting work at an underwater site. Using immersive virtual reality, we have developed an educational software to introduce maritime archaeology students to photogrammetry techniques. To test the feasibility of the software, a user study was performed and evaluated by experts. In the software, the user is tasked to put markers on the site, measure distances between them, and then take photos of the site, from which the 3D mesh is generated offline. Initial results show that the system is useful for understanding the basics of underwater photogrammetry

Saturation effects on mechanical excavatability of Roubidoux sandstone under selected rock cutting tools

This study investigated the differences in the cutting performance of two rock cutting tools in dry and saturated rock. For this purpose, a permeable quartzose sandstone was subjected to a series of full scale linear rock cutting tests, in both dry and saturated conditions, using a constant cross-section (CCS) disc cutter and a radial drag pick at a constant cutting speed. In this rock, saturation with water reduced the forces acting on the disc cutter by 27-48% (significant at 90% confidence), but also reduced the chip yield by nearly as much. Even though the specific energy of fragmentation went down 8-10%, the difference was not statistically significant. Contrary to the behavior under the disc cutter, water saturation increased the drag pick cutting forces by 9-10%, which is suggestive but not enough to be statistically significant. It did not increase the chip yield by a concomitant amount, however, so the specific energy went up by 28% (significant at 90% confidence). The unexpected differences in the effect of water saturation on the rock fragmentation response to these cutters might be explained by the effects due to their different fragmentation mechanisms, such as the relative size of the crushed zone that forms beneath the cutters. The relationship between cutting speed and rock permeability was expected to be a major factor influencing the effective pressure beneath a cutter in saturated rock. However, load-indentation tests with pore pressure measurement at the same speed showed that the pore pressure within the tested sandstone remained too low to affect the rock fracture process. Other possible mechanisms are discussed --Abstract, page iii

Settling Waterscapes in Europe

Pile dwellings have been explored over a vast region for a number of decades now. This has led to the development of different ways, methods, and even schools of under-water and peat-bog excavation practices and data analysis techniques under the influence of different research traditions in individual countries. On the one hand, these and other factors can limit our understanding of the past, whilst on the other hand they can also open up further avenues of interpretation. By collecting the papers presented at the 2016 session of the EAA in Vilnius, this book aims to take this diversity as an opportunity. The geographical scope extends from the Baltic to Russia, Belarus, Albania, North Macedonia, Bulgaria, Bosnia, Croatia, Greece, Germany, Austria and Switzerland to France. The volume thus provides a current insight into international research into life in and around a vast array of prehistoric waterscapes. Extensive multidisciplinary research carried out in recent years has provided new data with regard to the anthropogenic influence on the landscapes around Neolithic and Bronze Age pile dwellings, which allows us to characterise in more detail the lifestyles of the settlements’ inhabitants, the peculiarities of the ecological niche and the interaction between humans and their environment. The volume also contains various case studies that demonstrate the importance of scientific analyses for the study of settlements between land and water. Overall, the volume presents an important new body of data and international perspectives on the settlement of European waterscapes