HARVESTING
PART X:
Problem Addressed
Shallow areas of reservoirs often have extensive growths of macrophytes
("weeds").
plants may inhibit recreation,
intake structures,
release nutrients, and contribute to
oxygen depletions when their
tissues, and the dissolved organic matter they may release, are oxidized.
interactions of these plants in aquatic
Figure 4 illustrates the
systems.
Theory and Design
Harvesting is a procedure by which aquatic plants are cut, collected,
This technique can bring about some control of
and removed from the water.
plant regrowth, open the infested areas to recreation, lower the amount of
organic matter in the water column or deposited on sediments, and may con-
tribute to improvement in water quality through the removal of nutrients and
organic matter.
Most harvesters in use today are single-stage machines that cut the
vegetation with one horizontal and two vertical sickle-blade cutter bars,
via a conveyor from the cutterhead to a
store the collected plants
storage Compartment, and unload the plants at shore via additional conveyors
Machine storage capacities vary from about
aft of the storage compartment.
of cut vegetation, depending upon model and manufacturer.
6 to
Cutter
since hydraulic drag is con-
depth is usually limited to a maximum of
siderable if cutting operations are carried out at greater depths.
The oper-
Some manufacturers also sell
ator controls the depth of the cutting bar.
shore conveyor units-that convey vegetation from the harvester unit onto
trucks.
Also available are transporter units that are loaded by the harvester
at the harvesting site and transport the cut vegetation to shore.
Most
machines are built on pontoons and driven by diesel-powered paddle wheels.
In practice, the cutter bar should be lowered until it is just in. the
Most operators
mud and both root crowns and stems are cut.
attempt to work
parallel to shore.
Docks, trees, boulders, and other obstacles
hinder
operations or damage equipment.
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