Take a final look at the instruments and site. Confirm that all is operational,
clean and in good condition, with sufficient water, battery power and logger
memory to last until the next scheduled visit. Close up the instrument cabinet
and secure the site. Pick up any rubbish and tidy the area.
7.2
Data Processing And Management
This is an essential but sometimes overlooked part of the site operation.
Valuable recorded data may be lost or misplaced unless a data processing
system is established, documented and used routinely after each site visit.
Some sites are operated for many years, and ownership and operators may
change. A complete and documented data history is typically kept on a "data
processing" file for the site.
The appropriate system will depend on the project. It is possible to manage
data from a small number of sites as spreadsheets provided the system is well
organised and managed. Larger networks require specialised systems and
support.
The only copy of the data is the ASCII file on your computer hard drive. This
is why the backup copy has been left at the field site. The original ASCII file
should be archived as read-only in a system that is regularly backed up. This
should be done immediately you return from the site visit.
This original file may contain anomalies that have to be edited out, and
periods of lost or faulty data. Changes are made to a copy of the data (never
the original) and comments about what was changed and why, should be
appended. Blank periods, or estimates if possible, should be inserted if data
has been lost. These changes should be done by, or in consultation with, the
site operator.
This edited data should then be appended to previous data to maintain a
complete and continuous archive file of all data from the station. Review this
file to confirm that the latest data forms a sensible extension to previous data,
and that daily and seasonal evaporation and rainfall are sensible.
If apparent data problems are identified during data processing a note should
be added to the station visit file, to remind the site operator to attend to the
matter at the next site visit. The interaction between site operation, data
processing, reporting and review allows for continuous improvement in the
quality of the data produced.
Automatic Evaporation System
SITE VISITS AND MAINTENANCE 45
7.3
Site Maintenance
7.3.1
Overview
All evaporation pans need regular maintenance. It is recommended that sites
with pans be serviced at least once a month. Dust and debris will accumulate
in the pan and algae can grow in some conditions. Leaks can develop and
water supplies may need regular maintenance. The recorded data will be
effected.
At sites in dry areas a bird guard will prevent water loss from birds and
animals drinking from the pan. The guards also reduce the amount of wind
borne leaves and debris that lodge in the pan.
The water in the pan should be reasonably clear and clean. If algae growth is
excessive a commercial algaecide such as used for swimming pools, may be
added to the pan and supply tank
7.3.2
Site Surrounds
At fenced sites the vegetation and ground conditions inside the compound
should be similar to those outside. Keep any bushes and grass around the pan
trimmed to a level below the pan rim. Bushes further away should not be
higher than 25% of the distance from the pan. Any fence should be of an open
design with minimum wind resistance.
7.3.3
Evaporation Pan and Level Monitoring System
The evaporation pan will require regular cleaning. The colour of the interior
surface, the water clarity and the amount of surface litter, all affect the
recorded evaporation. The frequency of cleaning will depend on site and
seasonal conditions. The objective is to keep the pan reasonable clean
throughout the year.
Floating material and debris may be scooped out with a small swimming pool
net. Clean any dust and debris from inside the pan. The walls and bottom of
the pan can be brushed and the water swirled into a "whirlpool". Loose
material will accumulate in the centre of the pan and can be vacuumed off
with a siphon hose. If there is plenty of water at the site it may be simpler to
drain, clean and refill the pan.
UNIDATA
46 SITE VISITS AND MAINTENANCE
