Publications de Jean-Louis Boillat

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In flood protection engineering, side weirs or overflow dams are used to divert water in a controlled way into flood plains as soon as the discharge capacity of the main-channel is reached. Because of the lateral loss of water, the sediment transport capacity is reduced, resulting in local sediment deposition near the side overflow. Moreover, bed form characteristics such as length, height, steepness, and stoss and lee slope angle are affected by the lateral water withdrawal. Both phenomena are responsible

Uncontrolled overtopping during flood events can endanger embankment dams. Erosion of the downstream slope and scouring of its toe due to the high energy of the overflow can lead to breach formation and complete failure. Solution to overcome these dangerou ...

Reservoir sedimentation hinders the operation of the Lavey run-of-river hydropower plant (HPP) on the Rhone River in Switzerland. Deposits upstream of the gated weir and the lateral water intake reduce the flood release capacity and entrain sediments into the power tunnel. Past flushing operations of the relatively wide and curved reservoir have been inefficient. To improve sediment management, the enhanced scheme Lavey+ with an additional water intake and a training wall for improving flushing was set up.

Systematic investigations on positive and negative surge waves from upstream have been conducted in a 40 m long channel with a mean bed slope of 1.14? and non-prismatic bank geometries. The channel banks included macro-roughness elements, namely various cavities. In total, 41 different geometrical configurations have been investigated. The surge wave experiments confirmed the applicability of the elementary surge wave theory including secondary waves and wave breaking in the prismatic reference configuratio

The MINERVE project was initiated for flood management in the Upper Rhone river basin. Its first goal is the prediction of floods. The second one is the optimum management of the complex system of hydropower plants located in the basin in order to diminish the peak discharge in the Rhone River and its tributaries. The MINERVE Interactive Decision Support (MINDS) proposes turbine and bottom outlet preventive operations before the flood peak, for having storage volume in the reservoirs during the peak flow. T

Piano Key Weirs (PKWs) are an alternative to linear overflow structures, increasing the unit discharge for similar heads and spillway widths. Thus, they allow to operate reservoirs with elevated supply levels, thereby providing additional storage volume. As they are relatively novel structures, few design criteria are available. Hence, physical model tests of prototypes are required. This study describes comprehensive model tests on a sectional set-up of several A-type PKWs, in which the relevant parameters

The Upper Rhone River is located in the Swiss Alps. Several hydropower schemes with large reservoirs were built in the catchment area, strongly influencing its hydrological regime. In past decades, several floods caused disasters in the catchment area. The MINERVE project aims to improve the flood protection safety, focusing on their prediction. Furthermore, the multi-reservoir system is optimally managed to limit or avoid damages during floods. A “Decision Support Tool” called MINDS has been developed for

Le projet MINERVE de prévision et de gestion des crues en amont du Léman est aujourd'hui opérationnel. II vise la protection contre les inondations de la vallée du Rhône, dans les cantons du Valais et de Vaud, avec deux objectifs prioritaires. Le premier conceme la prévision hydrologique sur Ie bassin versant, pour une meilleure gestion des situations de crue en fonction de seuils progressifs d'avis, alerte et alarme. Le second repose sur une gestion préventive des aménagements hydroélectriques lorsque le b

In recent years, spillway rehabilitation has increased in importance and become the subject of many projects worldwide. One solution for this problem is the implementation of a new type of labyrinth spillway, called Piano Key Weir (PK-Weir ). This is an excellent alternative for increasing the overflow capacity of existing dams. Similarly to traditional labyrinth weirs, the hydraulic capacity of a PK-Weir is a function of its geometrical characteristics. Currently, there is a lack of systematic experiments,

The deposition behavior of fine sediment is an important phenomenon, which remains unclear to engineers concerned about reservoir sedimentation. In the present case bed level changes, suspended sediment concentrations, and flow velocities were measured in ...

Peak power production in hydroelectric storage power plants results in frequent and intense flow variations in the rivers downstream of the plants. Fish populations can be negatively impacted when subjected to these so-called hydropeaking phenomena. In res ...

To simulate the retaining capacity of an oil barrier in an uniform flow field, experiments were carried out in a laboratory flume at Ecole Polytechnique Federale de Lausanne (EPFL), Laboratory of Hydraulic Constructions (LCH) by using Light Expanded Clay A ...

The use of existing hydroelectricity multi-reservoir systems for flood protection may be an efficient approach in many catchment areas. The assessment of the protection potential offered by the hydropower plants during floods requires a comprehensive analysis of the catchment area, including the simulation of flood scenarios. A methodology for the optimization of turbine and bottom outlet operations of multi-reservoir systems during floods is presented. Based on a theoretical catchment configuration, the mo

The Zambezi Basin, a semi-arid 1.4 Mio km2 catchment area spreading across eight countries, constitutes a highly complex system. With several large dams, namely Kariba, Cahora Bassa, Kafue Gorge and Itezhi-Tezhi, the basin’s hydrology is also influenced by vast wetlands with high ecological value such as the Barotse plains, the Mana Pools or the Kafue flats. The African DAms ProjecT (ADAPT) is an interdisciplinary research project aiming to develop an integrated set of methods that help assessing the ecolog

elements. In addition to a prismatic reference channel, 41 different configurations of rectangular bank cavities have been investigated. The purpose was to study the effect of large-scale bank roughness on steady and unsteady flows. The macro-roughness of ...

Side weirs are widely used to control flow processes along a channel or river. The lateral loss of water reduces the sediment transport capacity in the main-channel leading to local sediment deposition near the overflow. The design discharge to be diverted ...

This paper investigates the morphologic impacts of the widening of tributaries in confluence zones by means of systematic hydraulic tests performed in a confluent laboratory flume. The confluent channels are connected with an angle of 90° and the main channel is 0.50 m wide. The tributary is 0.15 m wide in the reference configuration and enlarged to 0.30 m over a length of 0.45 m in the widened configuration. Experiments are carried out under mobile bed conditions. Sediments with a wide grain size distribut

The implementation of a new type of labyrinth spillway, called PKW (Piano Key Weir) reveals as a performing alternative for increasing the overflow capacity of existing dams. The optimal hydraulic design of such structure is however not obvious due to the large number of involved parameters. The present work explores experimentally the most relevant geometrical parameters, such as width, length, height and slope of keys and also the upstream and downstream flow conditions. The rating curve of a unit structu

As several of other run-of:river hydropower plants, the hydraulic scheme of Lavey on the Rhone River in Switzerland is concerned by continuous reservoir sedimentation. To determine the flood evacuation capacity of the weir as well as the flow distribution ...

The sediment transport capacity of the Avançon river through the city of Bex in Switzerland is limited. During the October 2000 flood event, water levels rose to danger limits. After the flood, the river channel was completely filled with sediments, with a uniform layer thickness comprised between 1.7 and 1.8m through the village. The return period of the flood event was estimated to be around 20 years, but the amount of transported sediments was extremely high for such an event.

Jean-Louis Boillat

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Influence of Lateral Water Withdrawal on Bed Form Geometry in a Channel

Aerated flows on stepped chutes with macro-roughness elements - Part I: Hydraulic characteristics

Modeling of Sediment Management for the Lavey Run-of-River HPP in Switzerland

Unsteady flow in a channel with large scale bank roughness

Decision Support System for the hydropower plants management : the MINERVE project

Hydraulic design of A-type Piano Key Weirs

The decision support tool MINDS for flood management in the upper Rhone river

La gestion des crues du Rhône en amont du Léman : de la prévision à la décision

Discharge Capacity of Piano Key Weirs

Evolution of sediment deposition and flow patterns in a rectangular shallow reservoir under suspended sediment load

Attractiveness of a lateral shelter in a channel as a refuge for juvenile brown trout during hydropeaking

Entrainment of floating granules behind a barrier

Optimization of the flood protection effect of a hydropower multi-reservoir system

Analysis of flow regime changes due to operation of large reservoirs on the Zambezi River

Propagation of surge waves in channels with large-scale bank roughness

One-Dimensional Numerical Modelling Of Mobile Bed Evolution In A Flume With A Side Weir

Experimental study on a widening tributary channel and its influence on the confluence morphology

Experimental parametric study for hydraulic design of PKWs

Lavey Dam - Physical and numerical analysis of flow and sediment transport in the Rhone River

Flood Risk Management of the Avançon river – physical model based study