#iahrFluvialHydraulics
River Flow 2024. 12th International Conference on Fluvial Hydraulics | Liverpool, UK. 2-6 September 2024
River Flow 2026. 13th International Conference on Fluvial Hydraulics. Call for proposals
This branch of geophysical hydraulics consists of the observation, analysis and control of fluvial processes. Any engineering intervention of a river (control) requires a preliminary assessment of the mechanisms involved (observation) and the prediction of their effects (analysis).
Physical processes in rivers are determined by the interaction of water and sediments. Waterflow and sediment transport are, therefore, traditional topics of study of this branch. Chemical and biological processes are also becoming more important, especially as their relationships to river morphology are recognised.
River engineers work in close contact with the natural environment. Their measures often interfere with natural processes. Environmental consideration and careful handling of fragile ecosystems are gaining increasing attention.
The morphology of a river is highly variable along its course, from the steepest branches of the upland regions down to the flat reaches of the estuary where rivers meet the sea. The behaviour of rivers in their middle course, where sediment transport is constituted by the relatively uniform material of the bed, has been investigated rather comprehensively by hydraulic engineers. Less attention has been paid to the upper and lower parts of the river. In the upper reaches sediment transport is directly controlled by the input from mass movement and surface erosion. In the lower estuary region, sediment motion is affected by salt, and tidal influences.
Consequently, the fluvial hydraulics Committee is now interested in research that involves components from other disciplines like biology, geomorphology, soil mechanics and oceanography.
Fluvial hydraulics needs contact with practice. The researchers depend on the engineers involved in practical river management, including construction. Their models and scientific approaches require data and experience from the field. On the other hand, the engineers doing practical work can benefit from research results and innovations by applying them in practice.
River processes: Experimental and theoretical investigations are being carried out to describe, in a more accurate and detailed way, various aspects of fluvial dynamics. These investigations include secondary flow and secondary sediment transport in geometrically complex configurations. Horizontal distribution in the bottom of non-uniform grainsize material, and dynamics of hyperconcentrated flows, like mud and debris flows. Overall models of the entire fluvial system, which would take into account the above-mentioned components, are also required for various engineering purposes.
Risk analysis and mitigation in fluvial systems: Besides the traditional one-dimensional analysis of the propagation of flood waters along a fixed-bed river, many other aspects of risk analysis and mitigation should be considered for general hazard assessment.
In the past years, attention has been focused on the two-dimensional spread of a steep wave in a valley produced by a ruptured dam. However, catastrophic inundations may also be related to large earth movements like the falling of a large mass into a reservoir, the sudden washing-away of a natural dam formed by landslides, or the rapid overaggradation of a mountain river, by mud and debris flow.
Mitigation of these effects, including reliable warning systems and structural and non-structural measures are currently under investigation.
Re-naturalisation of river environment: Due to increased environmental awareness by hydraulic engineers and the mounting pressure exerted by conservationist groups, the design of structural interventions in rivers must now consider environmental problems. In some cases, existing works decades and centuries old are under scrutiny for a possible "re-naturalisation".
As a "natural" configuration will generally correspond to more severe hydraulic conditions, research is needed to improve the compatibility between biological and engineering requirements, as well as to define new standards for the design of trained rivers.
Long-term evolution: While in some places (e.g. in Europe), future interventions in rivers will likely be limited to relatively small training and re-naturalisation works of secondary streams, new projects in other countries will probably involve important constructions on the largest rivers of the world.
In general, the necessity of environmentally acceptable and economically feasible sediment management which is oriented towards sustainable development must be given careful consideration
Improved methods for predicting the effects of new projects have to be developed, especially with regard to the hydrological and sedimentary regimes of the system. Because the reaction-time of the system depends upon its size, the evolution of very large rivers following these constructions may go on for centuries.
Special long term models that can simulate this time-scale should be prepared and tested against historical records. The history of river-water utilisation is full of examples of the unpredictable changes to river morphology and water quality as a result of river constructions.