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Today’s LectureWater levels and groundwater flow
AnnouncementsLecture
today: groundwater flow Thursday: guest lecture
Joy Jenkins, EPA: Captain Jack Superfund site
Lab Lab 1: Phase I ESA
rewriting? Lab 2: Surface water sampling
grading in progress? Lab 3: Soil sampling
report due Wed Oct 21 Lab 4: Well drilling
report due Fri Oct 30
AnnouncementsLab
Wednesday, Oct 28 Lab 5 Groundwater
sampling / Slug test East campus
Water Levels and Groundwater FlowMeasuring water levels in wells
single measurements electronic water level sensors simple tape measures inaccurate
long-term monitoring pressure transducers data recorders
Water Levels and Groundwater FlowWater level meters
sensors on tapes weighted probe on marked tape (PVDF*) water completes circuit across electrodes buzzer, light notification
depth relative to known elevation;
e.g., top of well casing depths to 1,000 ft accuracy to 0.01 ft or 1 mm
* polyvinylidene difluoride
Water Levels and Groundwater FlowWater level meters
advantages reliable, rugged easy to operate accurate
disadvantages probe, tape catches on casing joints false readings from cascading water,
condensation a lot of reeling!
Water Levels and Groundwater FlowWater level meters
sounders (acoustic) travel time for sound wave low frequency (50-200 Hz)
depth relative to known elevation;
e.g., top of well casing accuracy to 0.01 ft or 1 mm
advantages quick; no decontamination
disadvantages reflections off untrue well casing
Water Levels and Groundwater FlowLong-term monitors
pressure transducers accuracy 0.05% temperature compensation barometric
compensation
data loggers 100,000s of readings
Water Levels and Groundwater Flow
Water Levels and Groundwater FlowGroundwater flow contours contours of
groundwater elevation potentiometric surface
of surficial aquifer less relevant for confined
aquifers direction and velocity of
groundwater flow important for
contaminant transport less useful for DNAPLs
Water Levels and Groundwater FlowGroundwater flow contours water flows from
high to low head often follows
topography, but not always
slope hydraulic gradient (L/L)
direction planar surface defined
byat least threewater level measurements
Water Levels and Groundwater FlowCalculation of groundwater flow direction water levels in three wells
Water Levels and Groundwater FlowCalculation of groundwater flow direction water levels in three wells
28.1 ft
28.8 ft
28.4 ft
Water Levels and Groundwater FlowCalculation of groundwater flow direction water levels in three wells
28.1 ft
28.8 ft
28.4 ft
170 ft
Water Levels and Groundwater FlowCalculation of groundwater flow direction water levels in three wells
27.9 ft
28.8 ft
28.2 ft
170 ft
1 3
1 2 12
1 312
1 2
28.8 28.2170
28.8 27.9
113ft
x
x
x
h h Lh h L
h hL L
h h
L
Water Levels and Groundwater FlowCalculation of groundwater flow direction water levels in three wells
27.9 ft
28.8 ft
28.2 ft
170 ft
113 ft
Water Levels and Groundwater FlowCalculation of groundwater flow direction water levels in three wells
27.9 ft
28.8 ft
28.2 ft
170 ft
113 ft
Water Levels and Groundwater FlowCalculation of groundwater flow direction water levels in three wells
27.9 ft
28.8 ft
28.2 ft
170 ft
113 ft
Water Levels and Groundwater FlowCalculation of groundwater flow direction water levels in three wells
27.9 ft
28.8 ft
28.2 ft
170 ft
Water Levels and Groundwater FlowCalculation of groundwater flow direction water levels in three wells
27.9 ft
28.8 ft
28.2 ft
170 ft28.7 ft
76 ft
Water Levels and Groundwater FlowCalculation of groundwater flow direction water levels in three wells
27.9 ft
28.8 ft
28.2 ft
170 ft28.7 ft
76 ft
28.7 28.276
0.0066
dhdLdhdL
Water Levels and Groundwater FlowCalculation of groundwater flow direction water levels in three wells
27.9 ft
28.8 ft
28.2 ft
170 ft28.7 ft
76 ft
0.0066
Kdhv
ndLK
vn
Water Levels and Groundwater FlowGroundwater Flow Calculator
doi: 10.1111/gwat.12211
Water Levels and Groundwater FlowGroundwater Flow Calculator
Water Levels and Groundwater FlowGroundwater Flow Calculator
Water Levels and Groundwater FlowErrors in groundwater level measurement recording and transcription
errors condensation in well casing poor flow through well
screen nearby infiltration sources
water line leaks presence of LNAPL (“free
product”)
leads to errors in groundwater velocity and direction
LNAPL
Next LectureGuest lectureMeasuring aquifer properties – slug tests