( english version )
Hydrology ( 5 CFU )
Professore: DA ASSEGNARE

Finalità
The course deals with the methodologies of river flood estimation and hydrologic balance at basin scale. These notions are the basis for flood control and management of water resources. For these reasons the course is propaedeutical for the following “Hydraulic protection” (III year of LT) and “River basin management” (II year LS).

Programma
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.

Attività d'esercitazione
Numerical exercises are developed on the following topics: estimation of depth-duration-frequency curves; peak discharge estimation of given return period by means of direct methods and empirical formulas; flood hydrograph reconstruction starting from historical rainfalls by means of a rainfall-runoff model.

Modalità d'esame
Oral examination on the arguments developed in the lectures and in the laboratory activities.

Propedeuticità
Analisi I e II, Fisica I, Idraulica.

Testi consigliati
Maione U.: “Le piene fluviali”, La Goliardica Pavese, 1995.
Notes supplied by the teacher on the topics developed during the laboratory activities.

 
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