Groundwater level or piezometric
surveys are a snapshot of water levels in wells (and sometimes springs and
rivers) in an area at a point in time. The measurements are used to
create contours of equal height above sea level, similar to topographic
contours, which we call ‘piezometric contours’. Groundwater flow is
perpendicular to these contours at a regional scale.Proposed disclaimer/additional information in Canterbury
MapsGroundwater level or piezometric
surveys are a snapshot of water levels in wells (and sometimes springs and
rivers) in an area at a point in time. The measurements are used to
create contours of equal height above sea level, similar to topographic
contours, which we call ‘piezometric contours’. Groundwater will flow
perpendicular to these contours.In using these datasets, please consider:·
What scale are you interested in?
Local flow paths can be very different to regional flow paths due to changes in
local-scale permeability and recharge sources. Most of our contours are
regional scale, and may only provide an indication of potential local flow
paths. You may need to conduct your own measurements of a site to better
determine local flow paths.·
When was the survey undertaken? If
the survey is older, it may be that local groundwater conditions have
changed. There may be more than one survey of an area, and at more than
one time of the year. Groundwater contours and hence flow direction can
be different at times of lower and higher groundwater levels, and can depend on
external factors such as stream flow and irrigation schemes.·
How many wells were measured to create the
contours? Contours are more reliable in areas where more wells were
measured. Most of the contours have associated layers showing the wells
used to create them, which may be consulted to determine local-scale
reliability.
