- Hydraulic of free surface flows. Summary of the basic concepts of the steady flow motion. Unsteady flow and propagation of flood waves.
- Sediment transport and fluvial morphodynamic. Evolution trends of natural rivers, erosion and deposition process.
- Hydraulic modelling.
- Interaction of the interventions with the river dynamics.
Ugo Maione, Appunti di Idrologia - Le Piene Fluviali, La Goliardica Pavese
Sergio Montes, Hydraulics of Open Channels, ASCE Press, 1998.
Mechanics of Sediment Transport, Garde - Ranga Raju, McGraw Hill.
Luigi Montefusco - Lezioni di Idraulica - La Goliardica, Bologna.
Lectures notes, slides and material on Moodle platform.
Learning Objectives
The course aims to provide in-depth knowledge of river hydraulics, providing the tools and methods useful for understanding processes and for planning and designing interventions in the river environment.
At the end of the course the skills acquired will concern the application of the basic concepts to the practical problems of river hydraulics such as the hydraulic and sedimentological analysis of a watercourse, the design of the most common works, the classification and resolution of the problems of the natural water systems (evolutionary trends, flood propagation, intervention planning skills, hydraulic risk analysis skills, management and maintenance intervention evaluation and planning skills).
Full mastery of the course contents involves into the ability to autonomously judge the most appropriate intervention strategy in the management and maintenance of river basins, in the ability to clearly communicate and justify own choices in front of both a technical and non-technical audience; finally, in the ability to find, understand and apply solutions and methods necessary to solve the case study presented.
Prerequisites
Basic knowledge of fluid mechanics and flow hydraulics,
Hydrology - estimation of flood hydrographs,
basic knowledge of the use of GIS systems.
Teaching Methods
Frontal lesson, classroom exercise, seminar lesson, off-site exercise, group work.
Further information
Type of Assessment
The verification of learning objectives is carried out through an oral interview in which the student discusses the project work (presentation of the group work carried out) and 3 questions on the entire program of the course.
The project work is drawn up in groups of 2/3 students, and it consists in the implementation of a hydraulic model (2D or 1D/2D coupled) with open source software (preferential choice HEC RAS), in the hydraulic verification with unsteady flow of the actual and project status. The project work is agreed with the teacher, and reviewed before final delivery. The final project work report must be sent to the teacher at least three working days before the date of the exam session.
The following will be assessed: understanding of the basic concepts, clarity of presentation, critical reasoning skills on the case presented study, use of proper technical language.
Course program
Introduction and objectives of the course.
Characteristics of open channel flows on fixed bed: basic concepts and definition of the main variables. Uniform flow: definition of flow resistance coefficients. Steady flow: celerity of propagation of small perturbations, back water profile equation, local and generalized energy losses, boundary conditions, numerical solution of flow equation. Applications and examples of back water profile analysis. Detailed study of the hydraulic jump.
Unsteady flow: De Saint Venant equations (1D full model), propagation of flood waves, simplified models (cinematic and parabolic models), characteristic method, basic of numerical schemes for the solution of De Saint Venant equations.
Rating curve. Hydraulic measurements in natural channels. Roughness coefficient in mountain and alluvial stream, effects of vegetation in natural channels, theorical methods for evaluating the resistance induced by vegetation.
The hydrographic basin and the fluvial system. Fluvial sediments: properties and main characteristics. Methods for field sediment sampling.
Interaction between flow and mobile bed: conditions of incipient motion for mobile sediments, Shields criterion for incipient motion, changing in the threshold for incipient motion (e.g. the effects of longitudinal and transversal slopes, non-uniform sediment size distribution). Bed-forms, and flow resistance in mobile bed.
Sediment transport processes. Bed load transport, suspended load transport, diffusive model for suspended load transport, total load transport. Formulas for the estimate of sediment transport, formulas for sediment mixtures. Field measurements of sediment transport.
Equilibrium conditions of natural channels: continuity equation for sediment (Exner equation), sediment budget, average annual load and average flood event load, generalized erosion and deposition phenomena. Basic concepts of fluvial morphology: bankfull conditions in sand and gravel bed rivers.
Hydraulic modelling, shallow water equations. Practical application of HEC-RAS Software (1D/2D and 2D). Works for hydraulic risk reduction: expansion areas. Project aspects for the expansion areas: lateral weir flow, additional works, hydraulic verification of the expansion areas, interaction with sediment transport.
Transversal hydraulic works and related induced effects: analysis of the induced effects on sediment transport, sedimentation in artificial and natural reservoir, effects induced by dam removal. Slit check dams in mountain streams, hydraulic design of selective weirs. Selective weirs for woody debris.
Planimetric evolution of natural rivers and morphologies. Interaction between sediment transport and hydraulic structures in rivers: generalize and localize deposition. Criterion for bar formation, interaction with riparian vegetation.
Management of river system and river sediments. Sediment management plan: the example of Po River. Management of riparian vegetation: the example of Ombrone Grossetano River.
Sustainable Development Goals 2030
11 - Città e comunità sostenibili
13 - Agire per il clima