Fundamental of Groundwater Hydrology. Ted Way

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1 Fundamental of Groundwater Hydrology Ted Way

2 Outline Hydrologic cycle Aquifers Basic groundwater equations Well drilling and completion Groundwater level and velocity Definition of key hydrologic parameters Groundwater/surface water interaction Hydrologic tests Surface water monitoring/event sampling Ground water problems

3 體積 百分比

4 Outline Hydrologic cycle Aquifers Basic groundwater equations Well drilling and completion Groundwater level and velocity Definition of key hydrologic parameters Groundwater/surface water interaction Hydrologic tests Surface water monitoring/event sampling Ground water problems

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7 Precipitation Infiltration Recharge

8 Outline Hydrologic cycle Aquifers Basic groundwater equations Well drilling and completion Groundwater level and velocity Definition of key hydrologic parameters Groundwater/surface water interaction Hydrologic tests Surface water monitoring/event sampling Ground water problems

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13 Outline Hydrologic cycle Aquifers Basic groundwater equations Well drilling and completion Groundwater level and velocity Definition of key hydrologic parameters Groundwater/surface water interaction Hydrologic tests Surface water monitoring/event sampling Ground water problems

14 Basic Groundwater Equations Water level measurements Pumping tests Precipitation, Pumping records ' h h h h Kh h Kxx b + 2Kxyb + Kyyb + Kzzb + = S + W ' x x y y z b t v x Pumping tests Kx = φ e dh dx Geologic study (drilling, geophysical study) h = water level elevation b = aquifer thickness W = precipitation, pumping rates K = hydraulic conductivity S = storage coefficient V = groundwater velocity Φ = effective porosity

15 Outline Hydrologic cycle Aquifers Basic groundwater equations Well drilling and completion Groundwater level and velocity Definition of key hydrologic parameters Groundwater/surface water interaction Hydrologic tests Ground water problems

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17 Fetter C.W.,1999, Contaminant Hydrogeology, Second Edition, Prentice Hall

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22 Geologic Cross-Sections

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24 Fetter C.W.,1999, Contaminant Hydrogeology, Second Edition, Prentice Hall

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31 Purposes of Monitoring wells Groundwater level water level fluctuations, water quantity ground water flow direction Pumping tests/slug tests aquifer properties Water quality sampling in-situ measurement

32 Purposes of Monitoring wells Groundwater level water level fluctuations, water quantity ground water flow direction Pumping tests/slug tests aquifer properties Water quality sampling in-situ measurement

33 Water Level Measurement

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36 Water Sampling Sampling pumps Bailers

37 Ground Cover 12m Cement+5%Bentonite 3 to 5 casing volumes of water 36m 6m 5m 6m Bentonite Fine quartz Gravel pack 6m Screen

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41 Outline Hydrologic cycle Aquifers Basic groundwater equations Well drilling and completion Groundwater level and velocity Definition of key hydrologic parameters Groundwater/surface water interaction Hydrologic tests Surface water monitoring/event sampling Ground water problems

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45 Orange County, California

46 Basic Groundwater Equations Water level measurements Pumping tests Precipitation, Pumping records ' h h h h Kh h Kxx b + 2Kxyb + Kyyb + Kzzb + = S + W ' x x y y z b t v x Pumping tests Kx = φ e dh dx Geologic study (drilling, geophysical study) h = water level elevation b = aquifer thickness W = precipitation, pumping rates K = hydraulic conductivity S = storage coefficient V = groundwater velocity Φ = effective porosity

47 Outline Hydrologic cycle Aquifers Basic groundwater equations Well drilling and completion Groundwater level and velocity Definition of key hydrologic parameters Groundwater/surface water interaction Hydrologic tests Surface water monitoring/event sampling Ground water problems

48 K - Hydraulic Conductivity

49 Darcy s Law French hydrologist Henry Darcy (1856) Q ~ h L h L Q ~ 1/L Q ~ A Darcy s Law v Area A Q = KA h L L Q L K = hydraulic conductivity Q dh hl = dl L hydraulic gradient dh Q= KA dl Φ e = effective porosity K dh v = dl φ e

50 Hydraulic Conductivity ( m/sec ) Gravel Coarse sand Medium sand Fine sand Silt Till Clay Marine clay Karst Limestone Limestone Sandstone Siltstone Salt Anhydrite Shale Permeable basalt Fractured bedrock Weathered granite Weathered grabro Basalt Crystalline rock Transmissivity(m 2 /sec)= Hydraulic conductivity(m/sec)x Aquifer thickness(m)

51 Darcy s Law

52 Unconsolidated deposits Gravel 25-40% Sand 25-50% Silt 35-50% Clay 40-70% Rocks Fractured basalt 5-50% Karst Limestone 5-50% Sandstone 5-30% Limestone,dolomite 0-20% Shale 0-10% Fractured crystalline rock 0-10% Dense crystalline rock 0-5% Range of Values of Porosity

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54 Effective Porosity Clay and related materials 0 to 3% Gravel, Sand, Gravel and Sand 25 to 35%

55 Gravel Sand Clay

56 Darcy s Law v = K dh dl φ e K = hydraulic conductivity Φ e = effective porosity dh hl = dl L hydraulic gradient

57 S Storage Coefficient

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60 Storage Coefficient (Unconfined Aquifer) pumping Pump the well at a rate of 1 m 3 /minute for one day initial water level Volume pumped = 1 m 3 /min x 1,440 minutes = 1,440 m 3 unconfined aquifer cone of depression drainage effect Volume cone of depression = 14,400 m 3 storage coefficient (S) = Volume pumped /Volume cone of depression = 1,440 m 3 /14,400 m 3 = 10% = effective porosity = specific yield

61 Ranges of Values of Specific Yield Material No. of analyses Range Arithmetic mean Sandstone (fine) Sandstone (medium) Siltstone Sand (fine) Sand (medium) Sand (coarse) Gravel (fine) Gravel (medium) Gravel (coarse) Silt Clay Limestone From Morris and Johnson, 1967.

62 pumping Storage Coefficient (Confined Aquifer) storage coefficient (S) initial water level Confined Aquifer cone of depression = Volume pumped /Volume cone of depression = to = f(c m,c w ) matrix compaction water expansion S = γb(α+φβ)

63 Ranges of Values of Specific Storage Material Specific storage (m -1 ) Loose sand 1.0x x10-4 Dense sand 2.0x x10-4 Dense sandy gravel 1.0x x10-5 Plastic clay 2.0x x10-3 Stiff clay 2.6x x10-3 Medium-hard clay 1.3x x10-4 solid Rock, fissured, jointed 6.9x x10-6 Rock, sound Less than 3.3x10-6 i 19 2

64 Outline Hydrologic cycle Aquifers Basic groundwater equations Well drilling and completion Groundwater level and velocity Definition of key hydrologic parameters Groundwater/surface water interaction Hydrologic tests Surface water monitoring/event sampling Ground water problem

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68 Source: U.S. Geological Survey. Conceptual hydrological flow system in Georgia's coastal plains.

69 Base Flow

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74 Measurement Pumping test Precipitation record Pumping record ' h h h h Kh h Kxx b + 2Kxyb + Kyyb + Kzzb + = S + W ' x x y y z b t v x Pumping test Kx = φ e dh dx Geologic study (drilling, geophysical logs) h = water level elevation b = aquifer thickness W = precipitation, pumping rates K = hydraulic conductivity S = storage coefficient V = groundwater velocity Φ = effective porosity

75 Outline Hydrologic cycle Aquifers Basic groundwater equations Well drilling and completion Groundwater level and velocity Definition of key hydrologic parameters Groundwater/surface water interaction Hydrologic tests Surface water monitoring/event sampling Ground water problems

76 Aquifer Tests (1) Constant rate pumping test - T(K), S(multiple wells) (2) Slug tests - T(K)

77 Constant Rate Pumping Test Q K b Observation well r Pumping well

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80 Generator Computer Valve Flow meter Static water level drainage Troll Troll Pump

81 Slug test Computer Static water level Troll

82 (Slug test) (1) Static WL (2) Static WL

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84 Outline Hydrologic cycle Aquifers Basic groundwater equations Well drilling and completion Groundwater level and velocity Definition of key hydrologic parameters Groundwater/surface water interaction Hydrologic tests Surface water monitoring/event sampling Ground water problems

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95 60%

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97 Event monitoring schedule

98 Time 09:30 Duration (mins) 1 Water Level (M) 3.48 Water Level Change (M) 0 Record Event Sampling 09: :32 09: Every 5 data points 09:34 09: Or 09: :37 09: W L Change 0.05M 09: : : : : : : : : : : : : :

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102 Lab TSS (Total Suspended Solids)

103 Log Turbidity TSS Log

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105 Turbidity TSS Flow Amount of solids (erosion)

106 Outline Hydrologic cycle Aquifers Basic groundwater equations Well drilling and completion Groundwater level and velocity Definition of key hydrologic parameters Groundwater/surface water interaction Hydrologic tests Surface water monitoring/event sampling Ground water problems

107 Ground Water Problems Quantity(over-pumping) Reduction in aquifer storage Deeper wells, more equipment costs Subsidence Seawater Intrusion Quality(contamination) Seawater intrusion Pesticide, herbicide Industrial wastes Landfills Septic tanks

108 水位 Miami, Florida, USA Chloride concentration (ppm)

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115 Subsidence Material Compressibility (m 2 /N) - median Compressibility (m 2 /kg) - median Clay 1.0E E-06 Sand 1.0E E-07 Gravel 1.0E E-08 Jointed rock 1.0E E-08 Competent rock 1.0E E-09

116 This is a picture of the San Joaquin Valley southwest of Mendota in the agricultural area of California. Years and years of pumping ground water for irrigation has caused the land to drop. The top sign shows where the land surface was back in 1925! Compare that to where the man is standing (about 1977).

117 Source: U.S. Geological Survey (Circular 1182) Regions of the United States where land subsidence has been linked to groundwater pumping

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125 1:47am, September 21, 1999 Chi Chi, Taiwan M L 7.3 earthquake

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127 The focus is the point or center where the energy release starts. The epicenter is the point on the Earth's surface directly above the focus of the earthquake

128 The Mars Climate Observer, an US$125 million spacecraft, apparently burned up as it was about to go into orbit around Mars on September 23, The loss was largely blamed on an embarrassing failure to convert measurements from feet and inches into metric units.

129 Thank You!