Learning objectives
The main part of the course deals with the methodologies of flood estimation for the design of hydraulic structures and protection plans. The course topics are essentials prerequisites for the following courses of Hydraulic protection and River basin management.
The last part of the course concerns unsteady flows in natural rivers.
Prerequisites
Hydraulics
Course unit content
Hydrological processes. Hydrologic statistics. Floods. Peak discharge estimation. Unsteady free-surface flows.
Full programme
Hydrological processes. River basin main characteristics: Horton-Strahler laws, hypsographic curve, hillside slope, shape factors. Rainfall measurements: non-recording and recording rain-gauges; rainfall information collected in the Italian hydrologic annals (part I); Italian rainfall regimes; areal rainfall estimation: isohyetal maps, Thiessen polygons, grid methods. Statistical elaborations of short duration rainfalls: point and spatial depth-duration-frequency curves; areal-reduction factors. Excess rainfall estimation. Measurements of water stages and velocities in rivers: level-gauges, current meters; discharge derivation; stage-discharge relationships; stage and discharge information collected in the Italian hydrologic annals (part II); discharge-duration curves; Characteristics of Italian rainfall regimes; hydrologic cycle: control volume, processes, equations. Time-scales of main hydrological phenomena and return periods for design purposes;
Hydrologic statistic. Probabilistic treatment of hydrologic data; statistical parameters; probability distributions and their application in hydrology. Method of moments for parameters estimation. Plotting of experimental data on probability charts.
Floods. Origins and causes of floods in natural rivers; flood hydrograph analysis, base flow separation; rainfall-runoff mathematical description. Linear models: hypotheses and limits, convolution integral, IUH theory; IUH of more than one linear model in series and/or in parallel. Conceptual models: hypotheses and equations; IUH for the linear reservoir model, Nash model, time-area method; parameter calibration of linear models.
Peak discharge estimation. Direct methods and regional analysis; indirect methods based on rainfall-runoff models, critical rainfall duration; empirical formulas and order of magnitude for the main Italian rivers.
Unsteady free-surface flows. Flood routing: Hydrologic unsteady flow models: theory, parameter calibration and application of Muskingum method. Hydraulic unsteady flow models: De Saint Venant hypotheses and equations; initial and boundary conditions for sub- and supercritical flows; methods of solution: characteristics, finite difference (explicit and implicit), Courant-Fredrichs-Levy stability criterion.
Bibliography
Suggested textbooks
Notes supplied by the teacher at: http://lea.unipr.it
Maione U.: “Le piene fluviali”, La Goliardica Pavese, 1995.
Other useful books
Maione U., Moisello U.: “Elementi di statistica per l’Idrologia”, La Goliardica Pavese, 1993.
Moisello U.: “Idrologia Tecnica”, La Goliardica Pavese, 1998.
Chow V.T., Maidment D.R., Mays L.W.: “Applied Hydrology”, McGraw-Hill Book Company, 1988.
Teaching methods
Numerical Lectures with power point presentations. Numerical computations are developed on the following topics: estimation of depth-duration-frequency curves; peak discharge estimation; flood hydrograph reconstruction by means of a rainfall-runoff model, calibration and application of Lectures with Power Point presentations. Numerical computations are developed on the following topics: estimation of depth-duration-frequency curves; peak discharge estimation; flood hydrograph reconstruction by means of a rainfall-runoff model, calibration and application of Muskingum model; application of a unsteady flow mathematical model.
Assessment methods and criteria
Oral examination on the arguments developed in the lectures and in the laboratory activities.
Other information
web site at: http://lea.unipr.it
