ESS 312 - Hydrogeology Assignment 1
A network of 25 piezometers, including atransect of 7 multi-level piezometers, was installed in a unconfined sand aquifer to map and evaluate groundwater flow between a wetland (Beaver Bog) and adjacent lake (Antelope Lake). The 3.2 km2 study area corresponds to UTM Eastings of 387000 to 388600 m and Northings of 5104000 to 5106000 m; surface elevations and surveyed coordinates for the positions of the wetland and lake shorelines are shown in Table 1. Piezometers locations and surface elevations are given in Table 2, as well as corresponding piezometer stick-up heights, installed screen elevations, and top-of-pipe measurements for depth to water; auger refusal depths (i.e., assumed to be depth to bedrock from ground surface) are provided for the multi-level piezometers.
1. Calculate the hydraulic head for each of the single and multi-level piezometers. Report results in a table. Do not show calculations.
2. Complete a (hand drawn) areal flownet diagram (map) for groundwater flow between Beaver Bog and Antelope Lake. Set the x (east-west) andy (north-south) axes of the flownet to the UTM coordinates of 3.2 km2 of the study area. The scales of the x andy axes should be same. Clearly indicate equipotential lines on the flownet, using 1.0 m hydraulic head spacings, groundwater flow direction (arrows), flow/no-flow/constant head boundaries.
3. Determine the distance between piezometers and calculate bedrock elevations along the A4-T to B3-T transect of multilevel piezometers. Report results in a table. Do not show calculations.
4. Complete a (hand drawn) cross-sectional flownet diagram (map) for groundwater flow
along the A4-T to B3-T transect between Beaver Bog and Antelope Lake. Set the x axis of the cross-sectional flownet to the transect distance between survey point A4-T on the shoreline of Antelope lake (as the origin) and survey point B3-T on the shoreline of Beaver Bog. The y-axis will be mean elevation above sea level; use 95 masl at the origin to 140 masl. Note: you will need to apply an approximate vertical exaggeration (VE) near 16.5. Recall that VE = vertical (i.e., y axis ) scale / horizontal (i.e., x axis) scale. Indicate equipotential lines (using 1.0 m hydraulic head spacings), groundwater flow direction (arrows), flow/no-flow/constant head boundaries.
5. Prepare a short (no more than three pages) written summary that describes the nature of groundwater flow (i.e., directions and boundaries) in the study area; typed using a 12-point font with double-line spacing. Point form is unacceptable.
Table 1: Surveyed UTM coordinates for points along the shorelines of Antelope Lake and Beaver Bog in the study area.
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Surveyed UTM coordinates for points along shorelines of Antelope Lake
(elevation 120 masl)
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|
Survey Point
|
Easting (m)
|
Northing (m)
|
|
A1
|
387000
|
5105800
|
|
A2
|
387200
|
5105700
|
|
A3
|
387400
|
5105700
|
|
A4 - T
|
387600
|
5105800
|
|
A5
|
387800
|
5105900
|
|
A6
|
388000
|
5106000
|
|
|
|
Surveyed UTM coordinates for points along shorelines of Beaver Bog
(elevation 130 masl)
|
|
Survey Point
|
Easting (m)
|
Northing (m)
|
|
B1
|
387800
|
5104000
|
|
B2
|
388000
|
5104100
|
|
B3 - T
|
388200
|
5104200
|
|
B4
|
388400
|
5104300
|
|
B5
|
388600
|
5104400
|
Table 2: Number, UTM coordinates, surface elevation, installed screen elevation, auger refusal depth, piezometer stick-up, and measured top-of-pipe depth to water for piezometers in the study area; piezometers along the A4-T to B3-T transect are indicated by asterisks (*).