Garden Action

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Making a Watercourse

Watercourses built to wander over changes in level add further interest to a garden.  Few of us are lucky enough to have streams flowing through our garden or water sources that can be diverted to form a stream as a feature.

With the array of materials and low voltage water pumps that are now available, moving water even within a small garden is possible.  They can be made to meander over small changes of level or drop through steeper gradients in systems of falls with a pool at the bottom.

An imaginative pool and watercourse


The mound of excavated material from pond construction can be put to good use creating a bank down which water can flow.  Again, similar to pond construction, the proposed route should be planned and marked out, noting the changes in height.  A base using a flexible liner, covering it with stones or gravel and bordering with larger rocks gives a more natural appearance.
If water is moved by pump, a header pool to contain enough water to provide a constant flow is usually constructed at the start of the watercourse.  It can take the form of a large tank placed into the ground or a lined pool.

Start at the foot of the course, working back, checking frequently


Measuring liner needed.

The amount of liner needed depends on the route taken and the changes in level.  One piece of liner is sufficient if the route is straight and its dimensions should be the maximum width plus twice the depth, wide, by the total length.  An allowance should be made for overlap into header and base pools and changes in height.  A winding watercourse is made from a series of pieces, each overlapping by 15 cm to avoid folds.



Having a bank already, plan the size and mark out the watercourse.  The header pool should be at the highest point and the base pool at the lowest. Starting at the lowest point, cut steps in the bank to form the falls.  Have the ‘treads’ sloping to the rear to retain water in pools when the water stops flowing.  The header pool should be about 60cm square and 40cm deep.  Remove sharp stones, and compact the soil.  Spread a layer of polyester matting the length of the course, old carpet, once again, is also ideal.  Fit the flexible liner to the channel, allowing at least 30cm extra on either side as side walls. If pieces are used, cover the lower pieces with the upper pieces so that there is a 15cm overlap and water flows away from the join.  Next to the watercourse, dig a trench for the pipe to return the water from the base pool to the header pool. Place rocks in position to form the sides.  Lift the liner behind the rocks and pack in soil behind. Place the plants in the spaces behind and between the rocks.


Using preformed rigid units

Manufactured interlocking units can be bought.  They are placed in position in much the same way as preformed garden ponds, digging out corresponding holes, laying a sand base, levelling and back filling for added support.  As with preformed ponds, levels must be checked regularly.