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Yhd-12.3105 Subsurface Hydrology

Yhd-12.3105 Subsurface Hydrology. Introduction & Steady State Flow. Teemu Kokkonen. Water Engineering Department of Civil and Environmental Engineering Aalto University School of Engineering. Email : etunimi.sukunimi@tkk.fi Tel. 050-4073972 Room : 272 (Tietotie 1 E).

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Yhd-12.3105 Subsurface Hydrology

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  1. Yhd-12.3105 SubsurfaceHydrology Introduction & Steady State Flow Teemu Kokkonen Water Engineering Department of Civil and Environmental Engineering Aalto UniversitySchool of Engineering Email: etunimi.sukunimi@tkk.fi Tel. 050-4073972 Room: 272 (Tietotie 1 E)

  2. Schedule of the Course

  3. Components of the Course • Weeklyexercises (30 p) • Planningassignment (30 p) • Exam (40 p)

  4. Schedule of WeeklyExercises

  5. PlanningAssignment • Based on the data from the Jäniksenlinna groundwaterpumpingstationlocated in Tuusula • Experimental and challenging, buthopefullyalsointeresting and rewarding • There is no onecorretanswer, let us seehowfarwecanget… • Weapplyexistinggroundwaterflow software (MODFLOW) • There is a lot of workbutitcanbedivided • It is recommended to work as a group (2 or 3 students in a group) • It is allowed to workaloneifsomebodyprefersthat • GroupscanfreelybeformeduntilOct 7 • On Oct 7 the groupswillbefixed in the lecture • Finalseminar on WedNov 27,10:00 am -12:00 pm

  6. OptimaLearningEnvironment • ThiscoursehasitsownWorkspace in Optima • WeeklyExercisesFolder • Allweeklyexercisesare to bereturned in Optima • Labelyourfiles as follows: Lastname_Firstname_SSH_WENumber.extension • Eg. Kokkonen_Teemu_SSH_WE1.xlsx, Kokkonen_Teemu_SSH_WE1.docx • Everybodyhasher/hisownfolder in the WeeklyExercisesfolder • As defaultonly the person her/himself and Teemu havereading and writingpermissions in thatfolder • Youcanuploadfilesusing the Add a new objecttool • Excel workbooks and textdocuments • PlanningAssignmentFolder • Eachgrouphasitsownfolder in the PlanningAssignmentFolder • Allgroupmembers and Teemu haveread/writepermissions in thisfolder

  7. Noppa • The Noppa pagewillbe the home page of the course • Weeklyexercises and lectureslidescanbedownloadedfrom Noppa • Infromationduring the coursewillbedistributed as Noppa news items • Doyouallhavethemforwarded to youremail?

  8. Peer Support • Sometimesitmaybenecessary to compete, but… • One canaskwithwhom? Couldwestrive for the bestpossiblelearningoutcome and potentiallygainsomecompetitiveadvantageoverthemwhohavenotattendedthiscourse? • Could a functioningpeersupportresult in a betterlearnignresult for eveyone? • Person whoneeds help maygetinstructionsthatbringover the obstacle • Person for whom the exercise is not a problemmaystilldeepenher/hisunderstandingwhileexplainingit to someoneelse • It is knownthatoften the teacherlearns the most in the course... • Combiningunderstandingbetweentwoormorepeoplemay help to understandsomethingthatnone of themwouldhaveunderstoodbythemselves • Nicefeeling of helpingsomebodyorreceiving help shouldnotbeunderestimated In professional life, and alsomoregenerally in society, evenif the objective is to maximiseone’sownprofit the beststrategymaynotbe to merelyincreaseone’sownskillsoverothers – cooperativeteamplayersareappreciated

  9. OtherSupport • Naturally I try to help ifyougetstuck • In allcontactteachingsessions (lectures, exercises) youcanask me questionsabout the weeklyexercises and the planningassignment • Youcanalsowriteemail to me • If the question is simpleenough I mayevenreply… :-) • Morecomplicatedproblemsrequiringlongerexplanationsorhands-onworkarebetteraddressed in person, preferably in contactteachingsessionsbutalsosomeothertimecanbearrangedifnecessary

  10. SomethingAboutGrading • Weeklyexercises (30 p) • Eachexercisehas the maximumscorelisted • Planningassignment (30 p) • Evaluation of the groupwork + peerevaluation of eachgroupmember • Exam (40 p) • Understanding the exercisesgives a solidbasis for doingwell in the exam

  11. Literature • Electronic bookby Tuomo Karvonen • Canbefound in Optima • Wang, H.F. and Anderson, M.P., Introduction to groundwater modelling, W.H. Freeman and company, 1982 • Bear, J. and Verruijt, A., Modeling groundwater flow and pollution, Reidel, 1994 • Freeze, R.A. and Cherry, J.A., Groundwater, Prentice Hall, 1979 • A lot of material an be found in the libraries and online in the Web (keywords “groundwater” or “groundwater modeling”) • Let me and othersknowifyoufind a goodone!

  12. DH = H1 - H2 H1 H2 Darcy’s Experiment (Henry Darcy 1856) z1 H1 = + h1 = h1 • Discharge Q is • Directly proportional to A • Directly proportional to the water level difference in the two reservoirs DH • Inversely proportional to the length of the sand filterL h2=

  13. Hydraulic Head • Hydraulic head, piezometric head • Energy per unit weight • What components is the energy content of water composed of? • Gravitation: • Pressure: • Velocity: Incompressiblefluid dz / dt = v => dz = vdt Acceleration

  14. HydraulicHead • Energy content of waterE [J]: • HydraulicheadH [m]: In subsurfaceflow the velocitiesare typically low, let us ignore this p0 = atmosphericpressure, let us denoteitwithzero Gravityhead Presssurehead Pressurehead, let us denoteitwithh Gravityhead

  15. HydraulicConductivity • Let us recall Darcy’s experiment: where Q is discharge [m3/s], A is cross-sectional area [m2], DH is difference in the hydraulic head [m], and L is length [m] • The coefficient of proportionality (K) is known as the hydraulic conductivity, and its unit is:

  16. Permeability • Hydraulic conductivity K depends on the properties of both the media (permeabiliteetti) and the liquid (viscosity) k = permeability [m2] r = density [kg/m3] g = acceleration of gravity [m/s2] m = viscosity of the liquid [Ns/m2 = kg/m/s]

  17. Darcy’s Law 1D • Specific discharge is defined as the discharge per unit area (i.e. Q/A) and it is denoted with symbol q • Recognising that q (like velocity) is a vector and has a direction, and that the direction of flow is towards the decreasing hydraulic head yields: • Let the distance L tend to zero: dH / dx on hydraulinen gradientti

  18. Darcy’s Law 1D • Porosity n determines the relationship between the specific discharge (q) and the average flow velocity (v):

  19. Darcy’s Law 3D • In the homogeneous, isotropic case Darcy’s law can be written as follows:

  20. Heterogeneity and Anisotropy • When the properties of the aquifer (e.g. hydraulic conductivity) are not dependent on the location the aquifer is homogeneous – otherwise it is heterogeneous • When the properties of the aquifer (e.g. hydraulic conductivity) are not dependent on the direction the aquifer is isotropic – otherwise it is anisotropic Heterogeneity Anisotropy

  21. Heterogeneity and Anisotropy

  22. y x Anisotropy y Direction of anisotropycoincideswith the direction of ccordinateaxes. Gradient in the x-directioninducesflowonly in the x-direction. Direction of anisotropydoes NOT coincidewith the direction of ccordinateaxes. Gradient in the x-directioninducesflowboth in the x- and y-directions. x

  23. y q y’ x’ x Anisotropy Darcy’slaw in a more general form(2D): = 0 = 0

  24. Anisotropy • Specific discharge vector q and gradient vector can be expressed in both coordinate systems – and transformed from one coordinates system to another using a linear transformation

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