IDROLOGIA

Knowledge and understanding

The course aims to provide students with in-depth knowledge of the processes characterizing the different components of the hydrological cycle and of the methods for collecting, processing and analysing hydrological information used in design and management problems in water engineering.

At the end of the course, students will know and understand:

• the main components of the hydrological cycle and their interactions;
• the main hydrometeorological variables, their measurement methods and the characteristics of the instruments used;
• the main sources of hydrological data and the methods for organizing and processing observations;
• the fundamentals of statistical and probabilistic analysis applied to hydrological variables;
• the main probability distributions used in hydrology and the methods for parameter estimation and goodness-of-fit assessment;
• the methods for the spatial and temporal analysis of precipitation and the characterization of extreme rainfall;
• the morphometric characteristics of river basins and the methods used for their determination, including GIS-based approaches;
• the main empirical, semi-empirical and probabilistic methods for flood peak estimation;
• the processes underlying rainfall-runoff transformation and the main models used for flood hydrograph estimation;
• the fundamental concepts related to hydrogeological risk, extreme hydrological events and climate change.

Applying knowledge and understanding

At the end of the course, students will be able to:

• identify and use the hydrometeorological information required to address basic hydrological problems;
• process hydrological time series using statistical and probabilistic methods;
• perform frequency analysis of hydrological variables and select and fit appropriate probability models;
• estimate areal precipitation over a river basin;
• analyse extreme rainfall and derive rainfall depth-duration-frequency curves;
• define design hyetographs;
• delineate a river basin and determine its main morphometric characteristics, including through GIS tools;
• apply empirical, semi-empirical and probabilistic methods for flood peak estimation;
• estimate effective rainfall using the main available methods;
• determine the main characteristic times of a river basin;
• apply basic rainfall-runoff transformation models and derive flood hydrographs;
• use dedicated hydrological modelling software at a basic level.

Making judgements

Students will develop the ability to critically select data, methodologies and models appropriate to the specific hydrological problem under consideration, assessing the assumptions underlying the different procedures and the reliability of the results obtained.

Through exercises and the analysis of practical case studies, students will also develop the ability to compare different analysis and modelling methodologies and to critically interpret their results.

Communication skills

Students will acquire the ability to correctly use the technical terminology of hydrology and to clearly and rigorously describe hydrological processes, analysis methodologies and the results of hydrological investigations.

The preparation of a report containing the exercises carried out during the course will contribute to developing the ability to effectively organize and present data, calculation procedures and results. The final oral examination will also assess the ability to present and discuss the course topics.

Learning skills

Students will acquire the methodological tools required to independently investigate problems related to the analysis of hydrological processes and rainfall-runoff modelling.

They will also be able to consult textbooks, technical documentation and other sources of hydrological information and to independently use computational tools for data processing and interpretation.

UN 2030 Agenda Goals

The course contributes in particular to the following Sustainable Development Goals (SDGs) of the UN 2030 Agenda:

• Goal 6: protection and restoration of water-related ecosystems and efficient and sustainable use of water resources;
• Goal 11: development of cities and human settlements resilient to disasters and promotion of integrated risk management;
• Goal 13: improvement of knowledge and capacity related to climate change mitigation and adaptation, impact reduction and early warning;
• Goal 15: combating desertification and land degradation, including the effects of droughts and floods.

The course comprises a total of 93 teaching hours.

Teaching activities include theoretical lectures and classroom exercises carried out individually by students.

The theoretical lectures are aimed at providing knowledge of hydrological-cycle processes, measurement and processing of hydrometeorological variables, statistical and probabilistic analysis of hydrological data, characterization of precipitation and river basins, and rainfall-runoff modelling.

The exercises focus on:

• probabilistic analysis of precipitation;
• derivation of rainfall depth-duration-frequency curves;
• analysis of a river basin;
• estimation of flood hydrographs.

The practical activities are aimed at developing the students' ability to apply the knowledge and methodologies presented during the lectures and contribute to the development of independent judgement through the interpretation and discussion of the results obtained.

If the course is delivered in blended or remote mode, appropriate adjustments may be made to the above in order to ensure consistency with the programme reported in this syllabus.

Basic knowledge of Hydraulics is important for understanding runoff processes and the methods used for measuring and estimating streamflow.

Basic computer skills and familiarity with spreadsheets and word-processing software, particularly MS Excel and MS Word, are also useful for carrying out the exercises and preparing the required reports.

Attendance is not mandatory but is strongly recommended, particularly to enable participation in the exercises and facilitate the acquisition of the practical skills expected from the course.

Students who have been granted a specific status under University regulations will agree with the instructor on appropriate arrangements for attendance and completion of the exercises.

1. INTRODUCTION

Course presentation. Development of hydrology. Application examples related to extreme hydrological events and overview of the main analysis methodologies.

2. INTRODUCTION TO THE HYDROLOGICAL CYCLE

Components of the hydrological cycle – Precipitation – Evaporation and evapotranspiration – Surface runoff – Groundwater circulation – Water balance in a region – Distribution of water resources on Earth – Mean annual water balance of Sicily – Anthropogenic effects on the hydrological cycle.

3. HYDROMETEOROLOGICAL VARIABLES AND MEASUREMENTS

Classification of hydrometeorological variables – Properties of measuring instruments – Instruments for measuring hydrometeorological variables – Rain gauges – Recording rain gauges – Errors in precipitation measurements – Telemetry – Weather radar – Water level measurements – Staff gauges – Float gauges – Float-operated water level recorders – Bubble gauges – Ultrasonic gauges – Piezoresistive sensors – Instruments for velocity measurement – Horizontal-axis current meters – Vertical-axis current meters – Cableways – Velocity distribution in a cross-section – Streamflow calculation – Rating curves – Hydrographs.

4. HYDROLOGICAL DATA

Hydrological yearbooks – Air temperature – Characteristics of temperature stations – Daily temperature observations – Mean and extreme temperature values – Precipitation – Characteristics of rain gauge stations – Annual and monthly precipitation totals – Maximum-intensity precipitation – Annual maximum precipitation over consecutive days – High-intensity short-duration precipitation – Snow cover – Water Observatory of the Sicilian Region – Sicilian Agrometeorological Information Service – Other sources of hydrological information.

5. STATISTICAL AND PROBABILISTIC ANALYSIS OF HYDROLOGICAL DATA

Role of statistics within the mathematical tools of engineering – Random variables – Population and samples – Descriptive statistical analysis – Correlation and regression analysis – Frequency analysis – Definition of probability – Probability for discrete and continuous variables – Cumulative distribution function – Probability density function – Examples of probability distributions commonly used in hydrology – Parameter estimation methods – Selection of probability distributions – Goodness-of-fit assessment using graphical and analytical methods (e.g. probability plots, Kolmogorov test).

6. PRECIPITATION

Estimation of areal precipitation – Isohyetal method – Thiessen polygons – Extreme rainfall – Available data – Rainfall depth-duration-frequency curves – Rainfall depth-duration-frequency curves for durations shorter than one hour – Areal reduction factors for extreme rainfall – Design hyetographs – Rectangular hyetograph – Triangular hyetograph – Chicago hyetograph.

7. RIVER BASIN CHARACTERISTICS

Definition of river basin – River basin delineation – Shape characteristics – Slope – Orographic characteristics – Hypsometric curve – Drainage density – Hierarchical ordering of drainage networks – Horton's laws (law of stream numbers, law of stream lengths, law of stream areas) – River basin analysis using GIS software.

8. ESTIMATION OF PEAK FLOWS

Flood peak estimation – Empirical methods for natural catchments (Kresnik, Valentini, Pagliaro and Scimemi formulae) – Envelope curves – Semi-empirical methods for natural catchments (Forti and Gherardelli-Marchetti formulae) – Probabilistic analysis of flood data.

9. RAINFALL-RUNOFF TRANSFORMATION MODELS

Classification of rainfall-runoff models – Hydrological and hydraulic processes in rainfall-runoff models – Estimation of effective rainfall – Runoff coefficient for natural and urban catchments – Surface water film and depression storage – Infiltration – Horton equations – Curve Number method – Rational Method – Estimation of time of concentration – Time-area method – Linear reservoir method – Unit Hydrograph (UH) and Instantaneous Unit Hydrograph (IUH) methods – Soil Conservation Service dimensionless Unit Hydrograph method – Fundamentals of HEC-HMS software.

10. INTRODUCTION TO HYDROGEOLOGICAL RISK AND CLIMATE CHANGE

Definition of risk – Hydrogeological risk and extreme hydrological events: floods, landslides and droughts – Basic concepts of climate change.

Assessment activities are carried out during the course. Students are also required to prepare a report containing the exercises carried out during the course.

The final assessment will take into account:

• the results of the assessment activities carried out during the course;
• the methodological correctness, completeness and quality of the report containing the exercises;
• the outcome of the final oral examination.

The final oral examination is aimed at assessing the student's knowledge and understanding of the course contents, ability to apply the methodologies studied, ability to establish connections among different course topics, and ability to correctly use the technical terminology of the discipline.

Alternatively, students may take a single examination consisting of an oral examination covering the entire course programme. In this case, the final assessment will also take into account the quality of the exercises carried out.

The final grade will be awarded according to the following criteria:

• Fail: insufficient knowledge of the fundamental topics, significant shortcomings in the ability to apply the methodologies and inadequate use of technical terminology;
• 18–21: sufficient knowledge of the main topics and basic ability to apply the methods studied;
• 22–25: satisfactory knowledge of the topics and ability to correctly apply the main methodologies, with satisfactory analytical skills;
• 26–28: good knowledge of the course contents, good analytical and application skills and appropriate use of technical terminology;
• 29–30: in-depth knowledge, ability to critically integrate the different topics and independently address the proposed problems;
• 30 with honours: excellent and comprehensive knowledge, high degree of autonomy in applying the methodologies and excellent analytical, synthesis and communication skills.

Learning assessment may also be carried out online, should circumstances require it.

To ensure equal opportunities and in compliance with current legislation, interested students may request a personal interview in order to arrange any compensatory and/or dispensatory measures based on the educational objectives and their specific needs. Students may also contact the CInAP (Centre for Active and Participatory Integration – Disability and Specific Learning Disorders Services) representative of their Department.

The following is a non-exhaustive list of examples of topics and applications that may be addressed during the assessment:

1. Natural and anthropogenically modified hydrological cycle.
2. Hydrological variables and measuring instruments.
3. Hydrological yearbooks and the main information contained therein.
4. Frequency analysis of hydrological variables.
5. Probability distributions used in hydrology.
6. Parameter estimation methods and goodness-of-fit assessment.
7. Derivation and use of rainfall depth-duration-frequency curves.
8. River basin and its main morphometric characteristics.
9. GIS applications for river basin analysis.
10. Estimation of the time of concentration.
11. Methods for estimating effective rainfall.
12. Rainfall-runoff transformation models.
13. Application of the Rational Method.
14. Derivation and interpretation of flood hydrographs.