2.3 Hydraulic gradient analysis
Contours of groundwater elevations have been developed using data
obtained from monitoring wells around the pond at elevations -5 mTAW and
-20 mTAW. Four days have been selected to monitor the contours, two
representing winter conditions (01/19/2015 and 01/11/2016) and two
representing summer conditions (07/13/2015 and 07/19/2016). The contours
help in visualizing the groundwater elevations as well as the direction
of water flow. The flow of groundwater occurs in two distinct
directions, i.e. radially outwards from the infiltration ponds to the
pumping wells and radially inwards from the area outside the pumping
wells towards the pumping wells.
Vertical hydraulic gradients are calculated using heads at elevations
3.55 mTAW (approximately 3 m below the surface), 0.55 mTAW (approx. 6 m
below the surface) and -5 mTAW (approx. 11.5 m below the surface) at
well series WP 21, 22, 23 and 24 surrounding the infiltration ponds.
Analysis has been done on the average heads for the summer months (JJA)
and the winter months (DJF) for 2015 and 2016. The variation of
hydraulic heads with different seasons is also reflected on the vertical
hydraulic gradient. WP 6.2 is assumed to reflect the conditions exactly
underneath the ponds as it is located centrally between the two ponds.
Vertical hydraulic gradient has been calculated between WP 6.2 and the
pond bed to observe the variation of vertical gradient between summer
and winter