1 GROUNDWATER HYDROLOGY AND CONTAMINANT TRANSPORT CEVE 518 P.C. de Blanc C.J. Newell 1.Porosity and Density Continued 2.Saturation and Water Content 3.Darcy ’ s Law 4.Hydraulic Head Lecture 3

2 GROUNDWATER HYDROLOGY AND CONTAMINANT TRANSPORT CEVE 518 P.C. de Blanc C.J. Newell 1.Porosity and Density Continued 2.Saturation and Water Content 3.Darcy ’ s Law 4.Hydraulic Head Lecture 3

3 GROUNDWATER HYDROLOGY AND CONTAMINANT TRANSPORT CEVE 518 P.C. de Blanc C.J. Newell 1.Porosity and Density Continued 2.Saturation and Water Content 3.Darcy ’ s Law 4.Hydraulic Head Lecture 3

4 Capillary Rise in a Tube Domenico and Schwartz, 1992.

5 Charbeneau, Soil Moisture Held by Capillary Pressure

6 Soil Water Characteristic Curve is a Function of pore size Charbeneau, n clay n sand  r,lay  r,and Capillary forces hold water tightly in small clay pores. Larger sand pores produce lower capillary pressures.

7 Fetter, Relatively wide range of pore sizes from small to large results in widely varying capillary pressures. Narrow range of particle sizes results in relatively small range of capillary pressures. Soil Water Characteristic Curve is a Function of Sorting (Pore Size Distribution)

8 Soil Water Characteristic Curves Also Represent Water Content as a Function of Height Above Water Table Fetter, 1999.

9 Capillary pressure May Be More Easily Conceived of as the Independent Variable Charbeneau, capillary pressure (increasing height above water table) water content n clay n sand clay sand

10 GROUNDWATER HYDROLOGY AND CONTAMINANT TRANSPORT CEVE 518 P.C. de Blanc C.J. Newell 1.Porosity and Density Continued 2.Saturation and Water Content 3.Darcy ’ s Law 4.Hydraulic Head Lecture 3

11 Who Was Darcy? Henry Philibert Gaspard Darcy was born June 10, 1803 in Dijon, France. Admitted to the French School of Bridges and Roads in Paris, part of the Corps of Bridges and Roads. After graduation, he was eventually assigned by the Corps to a position in Dijon. In 1828, Darcy designed a 12.7 km system of aqueducts to supply the city of Dijon with surface water. The system included 28,000 m of pressurized surface lines and required no pumps or filters. Made important contributions to flow and friction loss in pipes, created an improved pitot tube design, and was the first to postulate the existance of a boundary layer in fluid flow. In 1856, carried out experiments while researching sand filters that lead to Darcy ’ s Law. Died unexpectedly January 3, 1858 from pneumonia during a trip to Paris.

12 Darcy ’ s Experimental Apparatus Domenico and Schwartz, 1992.

13 Darcy ’ s Experimental Data

14 Darcy ’ s Experimental Data

15 Darcy ’ s Data in English (One Experiment)

16 Velocity through Porous Medium “ Porosity ” = 0.5 Porosity = 0.5 PipePorous Medium Solid Void Space

17 Darcy ’ s Legacy Place Darcy, Dijon, France.

18 Can you Help the French Postal Service? 39 ¢ Young Darcy Old Darcy

19 GROUNDWATER HYDROLOGY AND CONTAMINANT TRANSPORT CEVE 518 P.C. de Blanc C.J. Newell 1.Porosity and Density Continued 2.Saturation and Water Content 3.Darcy ’ s Law 4.Hydraulic Head Lecture 3

20 Pressure and Elevation Heads - Laboratory Freeze and Cherry,  = pressure head z = elevation head h =  + z = total head

21 Freeze and Cherry,  = pressure head z = elevation head h = total head Pressure and Elevation Heads - Field

22 Horizontal and Vertical Head Gradients Freeze and Cherry, 1979.

23 Two Confined Aquifers with Different Heads Charbeneau, Groundwater will tend to flow from the top aquifer to the bottom aquifer. (Assuming that horizontal distance between piezometers is small)

24 Hydraulic Head is a Potential Field Hubbert (1940): potential – a physical quantity, capable of measurement at every point in a flow system, whose properties are such that flow always occurs from regions in which the quantity has a higher values of those in which it has lower, regardless of the direction in space. Potential fields and associated physical laws: Head (Darcy ’ s Law) Temperature (Fourier ’ s Law) Conduction of heat in solids Concentration (Fick ’ s Law) Diffusion of chemicals Fluid Flux Heat Flux Mass Flux

25 Horizontal and Vertical Head Gradients Freeze and Cherry, 1979.

26 Horizontal and Vertical Head Gradients Freeze and Cherry, 1979.

27 Potentiometric Surface – Dakota Sandstone Domenico and Schwartz, 1992.