1. Groundwater P = Q + ET + G +  S

2. Floridan Aquifer Extent

3. Hydrologic Horizons PressureTension θ pwp < θ < n θ fc < θ < n θ = n

4. Geologic Profiles (Stratigraphy)

5. Confinement

6. Transmissivity How much water can be moved horizontally –Function of thickness and K sat –Good measure of well productivity –Floridan is the most transmissive aquifer in the world

7. Loss of Potential

11. Potentiometric Surface Elevation of “free water surface” Where this surface and the ground intersect (and there’s no confinement) water seeps

14. Relevant Questions Where is the water going? –Potentiometric (piezometric) surface How much water is moving? How quickly? –Potentiometric surface and Darcys Law What level of natural assimilation is occuring? –Water quality modeling

15. Gainesville’s Well Field Also Lake City Jasper Geology Land use Conservation Easement

16. Murphree Wellfield Cone of Depression 1988 (Observed)2010 (Predicted)

17. How to make a sinkhole Pray for lots of Rain Suck a lot of water

18. Drilling and pumping Developed into a hole 300ft deep and 300ft wide Hundreds of sinkholes developed over a period of 6 hours.

19. Freeze Protection To protect strawberry yield during a January freeze in 2010, ~ 2 billion gallons per day of water pumped over a 5 day period. Voila.

20. Groundwater and Wetlands

21. Invasion Fire Subsidence Degraded wildlife habitat

22. Artesian Springs Where a confining layer exists, there may be a pressure potential in the aquifer HIGHER than the gravity potential of the surface. When tapped, water flows upwards

23. Soil water movement across a watershed boundary. P=Q+ET+G+ΔS Q groundwater = K A ΔH/L Darcy’s Law Darcy’s law can calculate vertical leakage through a clay layer AND lateral flow through a seepage face. Q is water crossing the defined area of the boundary in m 3 /day

24. K is hydraulic conductivity, or the capacity of the media to transmit water Most meaningful as saturated hydraulic conductivity K sat (m/day). Why? Q= K A ΔH/L

25. Measuring Ksat Constant Head Method –Constant depth of water (~50mm) on top of a saturated soil column with known dimensions (diameter, length) –Outflow volume collected over a period of time (e.g., 5 hrs) –Darcy’s Law to solve for Ksat

26. Measuring Ksat Hvorslev Method –Field measurement in screened wells K only determined 2 4 6 810 minutes.1.1 1.2.3.4.5.6.7.8 H/H o t 37 Log scale Linear scale H/H o =.37 casing Gravel pack Screen LeLe L e /R must be >8 R high K material r

27. Approximate K sat and Uses Ksat (cm/h)Comments 36 Beach sand/Golf Course Greens 18 Very sandy soils, cannot filter pollutants 1.8 Suitable for most agricultural, recreational, and urban uses 0.18 Clayey, Too slow for most uses <3.6 x 10 -5 Extremely slow; good if compacted material is needed

28. ΔH is the difference in H between two points Water flows from high ψ total to low ψ total (could be “up”) PointψGψGψPψPH A B C H = Ψ gravity + Ψ pressure H = level of water in an open well above some datum H A = ? H B = ? ΔH = ? Flow Direction?!?

29. H @ D? H@F? ΔH? Direction? 10 9 8 7 6 5 4 3 2 1 0

30. ΔH AD? Dir? ΔH BF? Dir? ΔH AF? Dir? ΔH/L BF?

31. Q=K A ΔH/L K?A?ΔH?L? Vertical leakage problem Ksat=0.001m/d Watershed=100 ha 0 1 2 3 4 5 6 Datum

32. Q = K * A * ΔH/L K = 0.001 m/d A = 100ha = 1,000,000 m 2 ΔH = 5-3 = 2m L = 2m Q = 0.001m/d x 1,000,000m 2 x 2m / 2m Q = 1,000 m 3 /day or 365,000 m 3 /year Q surface depth = 365,000 m 3 / 1,000,000 m 2 = 0.365m

33. Q=K A ΔH/L K=0.1m/d A=100m x 50m =5,000m 2 Δ H=108m-105m =3m L=1,000m Qm 3 /d= 0.1m/d * 5,000m 2 *0.003 = 1.5m 3 /d Lateral leakage problem

34. Groundwater Flowpaths at Streams

35. Groundwater Discharges

36. Groundwater Flowpaths

37. Next Time… Soil Water Storage