Keynote Speakers
Are hydraulic structures designed to handle ice?
The title question of this paper poses the question – Are hydraulic structures designed to handle ice? The answer to this question is qualified “no”. Though progress certainly has been made, ice concerns remain inadequately addressed or the possibility of ice concerns being forgotten. This paper addresses the question in terms of spatial scales: molecular, hydraulic structure, and global. Water is a material whose behavior is dictated by its molecules in response to pressures and temperatures exerted at the scales of hydraulic structure and Earth. Also, this paper argues that the further the hydraulic structure is located towards the lower extents of so-called “cold regions” consideration of ice concerns decrease and are at risk of being forgotten. When a structure is at a high latitude (commonly subject to frigid conditions), ice is considered, but there may be no assurance that such consideration is included in design or operation of a hydraulic structure. Case-study examples of hydraulic structures and ice illustrate that failure or at risk of failure owing to ice and dynamic frigid weather conditions typically associated with ice in continental U.S.: a labyrinth weir, stepped spillway, stilling basin, dam structure, bridges, inverted siphons, water intakes, pumps, and turbines. For example, in the USA spillways usually follow design guidelines stipulated by the U.S. Corps of Engineers or the U.S. Bureau of Reclamation. The problems are especially severe for hydraulic structures that experience their highest discharges during Spring when snowmelt (often combined with rainfall) and ice-cover breakup influence flow.
Hunter Rouse: Hydraulician, Leader, Historian
This Research deals with Hunter Rouse, Iowa Institute of Hydraulic Engineering. He submitted his PhD Thesis on the Brink Flow Problem to the University of Karlsruhe, where he was tutored by Theodor Rehbock. The Problem deals with a Strongly Curved Streamline Flow, which until then hardly received attention. Rouse was further fascinated by Jet Flow in the service of Fire Control, after the Pearl Harbor Disaster of 1941 had destroyed almost the entire US Pacific Fleet. Later, he investigated the Turbulence Patterns of the Direct Hydraulic Jump using, instead of Air-water mixture Flow, Air Flow only, with tests in the Wind Tunnel.
Rouse was a gifted Leader able to motivate his collaborators for Excellency, Accuracy and Human Qualities. He was IIHR Director from 1944 to 1966, during which years a number of Hydraulic Conferences was held at Iowa University. In 1950, the best contributions formed the basis of a notable book, his Engineering Hydraulics.
Following his sabbatical at the University of Grenoble in 1952, Rouse took an interest into the History of Hydraulics. Together with his PhD student Simon Ince, he presented the best-seller ‘History of Hydraulics’ in 1957. In 1976, the book ‘Hydraulics in the United States 1776-1996’ followed. The Lecture to be presented shall highlight these three items of Rouse’s career, using adequate photos and diagrams
Dam Safety and Surveillance: Concepts and Future Challenges
This keynote lecture describes Dam Safety and Surveillance concepts applied by the Swiss Federal Office of Energy and challenges that the Swiss dam industry is facing today and will face in the future. These include the implementation of new regulations, pumped storage schemes, flood verifications, dam ageing, climate change, the prioritisation of safety measures, reservoir slope stability, sedimentation, hydraulic discharge structures, bi-national safety and surveillance requirements, the impact of solar photovoltaic panels on dam safety and surveillance and other subjects. In accordance with Art. 29 of the WRFO (Water Retaining Facilities Ordinance, Status on the 1st January 2023) the main objectives of the keynote lecture are to ensure the exchange of information at an international level, secure expertise, promote research and to outline some of the tasks undertaken by the Swiss authorities, putting the emphasis on challenging problems.
The conclusions allow dam owners and operators to perhaps reassess their dam surveillance and safety concepts and take appropriate measures in a timely manner.
From Hazard to Habitat: Understanding Wood’s Impact in Fluvial Systems
One of the biggest challenges today is mitigating the effects of climate change on human society and ecosystems. Due to climate change, the frequency of flash floods increases, demanding a better understanding of transport processes in fluvial systems as well as innovative measures and resilient hydraulic structures that mitigate flood-related hazards. Recent floods demonstrated that not only water and sediment are being transported, but also other floating materials such as wood. For example, the hydraulic and geomorphic implications of wood accumulations at river infrastructures can significantly impact the flood hazard. This aspect needs to be accounted for to ensure a robust flood risk assessment. At the same time, many rivers worldwide, and specifically in densely populated countries such as Switzerland, have been confined for engineering purposes and consequently exhibit morphological and ecological degradation. The revised Swiss Water Protection Act demands the restoration of 4,000 eco-morphologically impaired river kilometers by 2090. To contribute to this effort, it is crucial to investigate the physical and ecological interactions for habitat creation in fluvial systems. The use of wood placements as an example of nature-based solutions for habitat creation has increased significantly in recent years. However, there is a lack of planning tools for the design of these measures, for example, to quantify the wake flow or footprint of suspended particle deposition to create targeted habitats. In this talk, I will present ongoing research on the hydraulic and geomorphic implications of wood and highlight the tension between hazard and benefit associated with wood.
Jet-driven scour processes between past and future
Scour at hydraulic structures represents one of the most “classic” problems in hydraulic engineering. The large number of highly valuable studies that have been published on the topic during the last century highlights the interest of the scientific (and professional) community to the topic. In fact, a reliable assessment of scour features is fundamental to minimize risks of potential structural failures and to preserve the functionality of hydraulic structures. However, despite the numerous efforts, we are still far from a complete and exhaustive understanding of scour phenomena. Namely, most of the proposed approaches are empirical or semi-theoretical, resulting in predicting tools that either lack generality or require ad-hoc calibrations/validations. More recently, first-principles-based methods have been developed to overcome these issues. Among them, one of the most promising is based on the phenomenological theory of turbulence (PTT). Such approach was pioneered in the first decade of the 21st century, but its applicability to a large variety of hydraulic structures and flow conditions has been only recently assessed. In this keynote lecture, the main methods to estimate jet-driven scour processes and their temporal evolution will be analyzed and discussed, focusing on recent theoretical advancements and still challenging aspects.
