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| Recommended approach and techniques |
Planning a channel seepage identification and measurement
investigation.
Which approach and techniques to use? |
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These guidelines are designed to enable users to make a serious
evaluation of suitable procedures that meet individual project
needs and objectives.
The logic presented in the guidelines is based on the conclusions
drawn from the investigation work undertaken in field trials.
A framework was established by a literature review and the current
practices of the RWAs, with the final guidelines largely developed
from the practical experience of the field trials. They take into
consideration the field conditions, the operational factors in
the Australian water industry and the available technology.
In addition,
the trade off between costs and the accuracy of results are addressed.
The investigations and trials conducted suggest that there are
preferred techniques and procedures for most investigations.
The guidelines are based around the need to generate the knowledge
required to undertake measurement of seepage and how to interpret
the results to meet a channel management objective. It is a circular
process involving the following key tasks:
| Local
or intermediate to large scale? |
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A fundamental issue related to planning a channel
seepage identification and measurement investigation and the selection
of techniques
is the scale of the investigation. Three scales were referred
to in General issues in channel
seepage identification and measurement, Issues of scale:
- Local sites where the focus may be
on addressing a particular previously identified issue: short
(up to approximately 400m length)
- Intermediate to large-scale investigations
where business objectives suggest a need for investigation even
though the specific
distribution and rate of seepage is not known. This may form the basis for
more detailed investigation at a later date: Hundreds of metres
to tens of kilometres
- Macro-scale investigations
are not detailed in these guidelines. Generally macro-scale
investigations are comprised of
an inflow-outflow process conducted at a regional or sub-regional level. Remote
sensing
techniques may also be useful at this regional level of
investigation.
The six step approach is
an overall recommended approach. It includes specific recommendations
for local and intermediate to large-scale identification
and measurement.
| Other
considerations |
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In addition to issues of scale, it is important to consider:
- Physical conditions: soil and water conditions in the
vicinity of the channel and within the channel
- Seepage mechanisms:
shallow surface and/or vertical seepage
For a description of these other considerations see General
issues in channel seepage identification and measurement.
| Related
pages |
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Next: 1 Define objectives |
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