Environmental Engineering

Introduction to the course. Introduction to geophysical methods for environmental engineering. Environmental Geophysics and climate change. Direct and indirect measurements. Resolution and depth of investigation. Workflow of geophysical surveys. 1. SEISMIC methods 1.1. Basic principles: propagation and attenuation of seismic waves. Seismic properties of soils, rocks and fluids. Wyllie's equation. 1.2. Seismic instruments: sources, receivers, seismographs. 1.3. Direct methods: down-hole and cross-hole 1.4. Seismic refraction: waves at intefaces, critical refraction, head wave 1.5. Seismic tomography: introduction to data inversion. 2. SONAR methods 2.1. Basic principles of SONAR methods: scattering and attenuation of acoustic waves, resolution 2.2. MultiBeam, Side Scan Sonar and Sub-bottom profiling (Chirp): data acquisition and processing 3. RADAR methods (Ground Penetrating Radar - GPR) 3.1. Electromagnetic properties of soils, rocks and fluids. Archie's law. 3.2. Basic principles of GPR method: propagation and attenuation of EM waves; scattering and reflection 3.3. GPR data acquisition 3.4. GPR data processing 4. DC Electrical methods 4.1. Basic principles: electric potential, apparent resistivity, electrode configurations (array); electric potential for DC point sources: solution with the finite-element method 4.2. 2-D Electrical Resistivity Tomography (ERT): data acquisition and inversion. 4.3. 3-D ERT and best practices 4.4. Time-domain Induced Polarization (TDIP) method: data acquisition and inversion. 5. Low-frequency electromagnetic method (LFEM) 5.1. Basic principles of EM induction: AC sources; fixed-source method (Slingram) 5.2. Time-domain EM methods: Transient Electromagnetic Method (TEM) and case history. 6. Integration of geophysical data: motivation, advantages and disadvantages. Reconstruction of a multi-parameter model and derivation of hydraulic, geotechnical and environmental parameters. 7. Laboratory activities Small-scale simulations of each technique studied will include data acquisition, processing and interpretation in order to retrieve a multi-parametric model representative of the subsoil. Simulations will be held in the laboratory or in field, depending on the particular technique.

Mathematics (partial derivatives, integrals, differential equations, vector fields, complex numbers), physics (geometrical optics, electromagnetic fields, wave propagation) and solid mechanics (theory of elasticity) are required even if all basic principles will be reviewed during the course.

Reference book: Everett, M. E. (2013). Near-surface applied geophysics. Cambridge University Press. PDF lectures notes on selected topics will be available on the e-learning platform "Sapienza" Moodle (elearning2.uniroma1.it)

The teaching activity will be organized in classroom lectures, for learning the theoretical principles of the geophysical methods and their application to environmental engineering through data processing and laboratory activities, to be performed at the end of each "module" related to the single studied method. Students will participate to data acquisition, processing and interpretation, using software made available to them. Groups exercises will be held for improving the problem solving skills.

Although optional, it is strongly recommended attending both lectures and practical exercises (class exercises nad filed demostrations), for integrating information included in the reference books and notes.

The final evaluation (out of thirty) will be as follows: - Written (mandatory): 5 closed-ended questions (1 point each) + 1 open-ended question on the theoretical principles of the geophysical methods (max. 5 points) - max. achievable points: 10 - Practical (mandatory): 2 exercises in Excel (max. 5 points each) on the practical application of geophysical methods to environmental engineering (ex. 1 on ch. 1 and 2, ex. 2 on ch. 4 and 5) - max. achievable points: 10 - Oral (mandatory): 1 question on the geophysical methods applied to environmental engineering (max 10 points)

- Butler D. K. Near-surface Geophysics. Society of Exploration Geophysicists, 2005. - Stein S., Wysession M. An introduction to seismology, earthquakes, and earth structure. John Wiley & Sons, 2009. - Telford W.M., Geldart L.P., Sheriff R.E. Applied geophysics. Cambridge university press, 1990.

The teaching activity will be organized in classroom lectures, for learning the theoretical principles of the geophysical methods and their application to environmental engineering through data processing using Excel and Python and laboratory activities, to be performed at the end of each "module" related to the single method. Students will participate to data acquisition, processing and interpretation, using software made available to them. Groups exercises (2 or 3 students) will be held for improving the problem solving skills.