Designing a Watercourse for Your Liner Pond

Designing and installing a watercourse from scratch can be an extremely satisfying project, but it is a difficult step up from installing a preformed watercourse.  With preformed watercourses, the shape, water flow, and layout of the waterfall are predefined for you (all you have to do is to hook up the pump to the intake nozzle).  A liner-based watercourse, on the other hand, will require advanced pond design knowledge and experience in controlling the flow of water.  Ultimately, the main reason to design your own watercourse is to create a body of running water that will look both natural and professional.

A watercourse needs to be designed such that the stream looks as natural as possible.  This means that adding rocks and plants to the stream will be essential in order to make it blend in with the natural landscape.  Go to gurgling streams in the hills and slower flows in meadow creeks, and observe how water flows more quickly when a streambed narrows, and slower in wider spots.  Observe how rocks and other obstacles affect the speed and direction of water.  These are considerations that you will have to take into account when you are designing your own stream.

A stream or watercourse usually runs from a waterfall to a pond.  Excavations with natural gentle slopes are good lays for watercourses.  However, streams can be set in level ground. A stream only needs a one-inch drop in elevation per ten feet to affect a flow from the top down to the reservoir.  If the slope of your land drops more steeply, you will need to create a series of longer streams/pools with vertical drops between them.  You will likely require additional overlapping liners to form each stream.  Your layout may lend itself to one or more vertical waterfalls along the stream.  The higher the vertical drop of water, the larger and deeper the pool under the falls should be, in order to minimize splashing.

Begin your design with a site plan and make sketches depicting the stream's placement, pool tiers, waterfalls, depth, cross-over features (E.g. bridges, and stepping stones), and flow direction within your landscape.  Keep in mind that streams are more interesting if they are not completely visible from the viewer's perspective.   Furthermore, a stream should be designed with an occasional dam, so that it will hold water if the pump ever stops operating.  The catch basic at the end of the stream should be large enough to hold all the water if the pump is shut off.

When laying out your design, make sure to consider where the piping will go.  Ideally, you want to lay out the piping in a straight and direct pipeline from the source of the watercourse (I.e. the pump/filter) to its upper end.

Curves and bends create a natural look.  Water always flows faster on the outside of a curve, and it pushes harder against the outside of the curve than its inside.  Avoid long stretches of shallow water because algae will build up if the current is too slow.  We recommend applying barley straw or barley straw extract to the stream because barley straw has been known to reduce algae if applied early in the season.

Consider adding bog gardens filled with marginal and bog plants next to the stream.  Bog gardens can create a natural transition from the stream to the surrounding area.  Ensure that the bog garden does not interfere with the flow; add them to the outside edges of bends in the stream.

Placement of natural rock determines the final appearance of the stream.  Acquire a variety of rocks in different sizes and shapes so you can experiment with the end result.  Use larger rocks to direct and channel water, and smaller stones to create a ripple effect as water flows over them.  These rocks will add different sounds as water rushes over or by them.  Keep in mind that rocks on the outside of a curve will create more turbulence.  Rocks can also be used to decrease the width of the stream, and to increase the speed of the water.  Unfortunately, rocks in the stream can also trap debris, which will create a dam effect that forces water over the stream bank.

After you have designed a watercourse, you will need to test it to examine how the water is flowing.  When testing water, look for areas along the stream where water may spill out.  It is pertinent that you keep the water contained within the stream, otherwise, your pond will require constant refilling.  The sides of the stream may need to be reworked so that the banks always contain the water.

You may have to resize your pump if it cannot provide you with the desired flow.   After constructing the streambed, you can use a garden hose to obtain a visual idea of how much flow is required.  Flow rate (in gallons per hour, or GPH) can be determined with a flow meter.  Alternatively, you can determine the GPH flowing from your garden hose by filling a 5-gallon bucket using the house.  Divide 60 minutes by the number of minutes it takes your hose to fill the 5-gallon bucket.  Multiply the quotient by 5.  After observing the flow of your garden hose through the stream, determine if you need to increase or decrease the GPH flow rate to the stream.  The general rule of thumb is that water needs to recirculate once every 2 hours.  However, please keep in mind that extra GPH will be required in order to compensate for the height and length of your stream.  Please consult GardenSM.com's pump sizing instructions for further information about finding the right pump.

Designing a streamlet is an advanced and challenging project, however, it can add enormous benefits to the finished pond.  Not only does a well-designed streamlet blend into its natural environment, but it also provides the owner with the soothing sounds of trickling and running water.