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Calculus Review. Slope. Slope = rise/run = D y/ D x = (y 2 – y 1 )/(x 2 – x 1 ) Order of points 1 and 2 abitrary, but keeping 1 and 2 together critical Points may lie in any quadrant: slope will work out
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Slope • Slope = rise/run • = Dy/Dx • = (y2 – y1)/(x2 – x1) • Order of points 1 and 2 abitrary, but keeping 1 and 2 together critical • Points may lie in any quadrant: slope will work out • Leibniz notation for derivative based on Dy/Dx; the derivative is written dy/dx
Exponents • x0 = 1
Derivative of a line • y = mx + b • slope m and y axis intercept b • derivative of y = axn + b with respect to x: • dy/dx = a n x(n-1) • Because b is a constant -- think of it as bx0 -- its derivative is 0b-1 = 0 • For a straight line, a = m and n = 1 so • dy/dx = m 1 x(0), or because x0 = 1, • dy/dx = m
Derivative of a polynomial • In differential Calculus, we consider the slopes of curves rather than straight lines • For polynomial y = axn + bxp + cxq + … • derivative with respect to x is • dy/dx = a n x(n-1) + b p x(p-1) + c q x(q-1) + …
Example y = axn + bxp + cxq + … dy/dx = a n x(n-1) + b p x(p-1) + c q x(q-1) + …
Numerical Derivatives • ‘finite difference’ approximation • slope between points • dy/dx ≈Dy/Dx
Derivative of Sine and Cosine • sin(0) = 0 • period of both sine and cosine is 2p • d(sin(x))/dx = cos(x) • d(cos(x))/dx = -sin(x)
Partial Derivatives • Functions of more than one variable • Example: h(x,y) = x4 + y3 + xy
Partial Derivatives • Partial derivative of h with respect to x at a y location y0 • Notation ∂h/∂x|y=y0 • Treat ys as constants • If these constants stand alone, they drop out of the result • If they are in multiplicative terms involving x, they are retained as constants
Partial Derivatives • Example: • h(x,y) = x4 + y3 + x2y+ xy • ∂h/∂x = 4x3 + 2xy + y • ∂h/∂x|y=y0 = 4x3 + 2xy0+ y0
Gradients • del h (or grad h) • Darcy’s Law:
Earth’s Water • Covers approximately 75% of the surface • Volcanic emissions http://earthobservatory.nasa.gov/Library/Water/
One estimate of global water distribution http://earthobservatory.nasa.gov/Library/Water/
Hydrologic Cycle • Powered by energy from the sun • Evaporation 90% of atmospheric water • Transpiration 10% • Evaporation exceeds precipitation over oceans • Precipitation exceeds evaporation over continents • All water stored in atmosphere would cover surface to a depth of 2.5 centimeters • 1 m average annual precipitation http://earthobservatory.nasa.gov/Library/Water/
Hydrologic Cycle In the hydrologic cycle, individual water molecules travel between the oceans, water vapor in the atmosphere, water and ice on the land, and underground water. (Image by Hailey King, NASA GSFC.) http://earthobservatory.nasa.gov/Library/Water/
Water (Mass) Balance • In – Out = Change in Storage • Totally general • Usually for a particular time interval • Many ways to break up components • Different reservoirs can be considered
Water (Mass) Balance • Principal components: • Precipitation • Evaporation • Transpiration • Runoff • P – E – T – Ro = Change in Storage • Units?
Ground Water (Mass) Balance • Principal components: • Recharge • Inflow • Transpiration • Outflow • R + Qin – T – Qout = Change in Storage
DBHydroRainfall Stations • Approximately 600 stations
Spatial Distribution of Average Rainfall http://sflwww.er.usgs.gov/sfrsf/rooms/hydrology/compete/obspatialmapx.jpg
Evaporation Pan www.photolib.noaa.gov/ historic/nws/wea01170.htm
Pan Evaporation • Pan Coefficients: 0.58 – 0.78 • Transpiration • Potential Evapotranspiration • Thornwaite Equation
Watersheds http://www.bsatroop257.org/Documents/Summer%20Camp/Topographic%20map%20of%20Bartle.jpg
Watersheds http://www.bsatroop257.org/Documents/Summer%20Camp/Topographic%20map%20of%20Bartle.jpg
Stage Recorder http://gallatin.humboldt.edu/~brad/nws/assets/drum-recorder.jpg
River Hydrograph http://cires.colorado.edu/lewis/epob4030/Figures/UseandProtectionofWaters/figures/ColoradoRiverHydrograph.gif
Well Hydrograph http://wy.water.usgs.gov/news/archives/090100b.htm
Stream Gauging • Measure velocity at 2/10 and 8/10 depth • Q = v*A • Rating curve: • Q vs. Stage http://www.co.jefferson.wa.us/naturalresources/Images/StreamGauging.jpg
Ground Water Basics • Porosity • Head • Hydraulic Conductivity
Porosity Basics • Porosity n (or f) • Volume of pores is also the total volume – the solids volume
Porosity Basics • Can re-write that as: • Then incorporate: • Solid density: rs = Msolids/Vsolids • Bulk density: rb = Msolids/Vtotal • rb/rs = Vsolids/Vtotal
Cubic Packings and Porosity Simple Cubic Body-Centered Cubic Face-Centered Cubic n = 0.48 n = 0. 26 n = 0.26 http://members.tripod.com/~EppE/images.htm
FCC and BCC have same porosity • Bottom line for randomly packed beads: n ≈ 0.4 http://uwp.edu/~li/geol200-01/cryschem/ Smith et al. 1929, PR 34:1271-1274
Porosity Basics • Volumetric water content (q) • Equals porosity for saturated system
Sand and Beads Courtesey C.L. Lin, University of Utah