There’s intriguing sensual value in water gardens that have audible qualities. Creating a cascade or waterfall adds soothing movement and sound to any feature, as well as can help boost property value (if done right). There are numerous ways to achieve falling water effects in your water garden.
Protect still-water plants from fast-moving currents by constructing a deep pool beneath waterfalls, then filtering and dividing the water through rocks before it reaches and enters the main pool.
Photo Credit: ©2001 Dolezal Publishing/John M. Rickard
Consider installing pre-built waterfall units as part of your stream. They contain biologic filters of lava rock to keep the water clear and free of organic debris, and they’re disguised by framing them with surrounding stone.
Photo Credit: ©2001 Dolezal Publishing/John M. Rickard
Each cascade or waterfall requires an abrupt change in elevation that interrupts the flowing stream or watercourse. Generally, a fall of about 6 inches will deliver the optimum look and sound. Plan on a deep receiving pool beneath each waterfall, then a slowly rising streambed as the flow approaches the next waterfall.
A foundation stone sits at the point of the elevation change with a spill stone atop it. The spill stone’s placement is very important, both vertically and in orientation to level. It should extend over the edge of the foundation stone, so that the water can fall freely into the stream or pool below. It should be placed to partially dam or slow the stream, building a head of water behind it on the upstream side.
The spill stone’s design regulates the way the water falls. Gate stones set to each side channel the water toward the stone’s center and block flow around its edges. In a cascade, the water runs in a smooth curtain over a flat sill from one level to another. In a waterfall, the water splashes down over a rugged rock formation falling cleanly into the pool below. The width of the spill stone – and how water is channeled to it – helps determine the appearance and intensity of the falls. Both smooth and splashing waterfall styles are common in nature and are appropriate for either a stream or a watercourse, depending on your desired effect.
A garden stream with a cascade or waterfall requires a recirculating pump and delivery pipe specifically designed to deliver a high volume of water. The greater the elevation change from the header pool to the reservoir pool, the stronger the pump required. Choose a pump with excess capacity to create streams and watercourses with rushing water that flows in a torrent.
Creating cascades and waterfalls requires planning prior to excavation. Study some creeks and streams in your area to gain a better understanding of how naturally occurring streams flow. (Especially look at points where water falls.) Observing wild streams will help you create a water feature that closely resembles nature.
Waterfall Installation
Waterfall Installation - Step 1
If you need more than one liner to cover the excavated area and a liner seam joint is necessary, overlap liners by 18 inches, with the upstream liner above that of the lower stream section, positioning the seam under the site of the future waterfall. Apply double-sided EPDM joint tape between the two liner sections to create a waterproof seal, forming an interlocking Z-shaped joint with two moisture barriers to prevent leaking.
Photo Credit: ©2001 Dolezal Publishing/Robert J. Dolezal
Waterfall Installation - Step 2
Position the foundation stones until they’re exactly level within the excavated shelf atop the liner. Use mortar or special black, waterproof, expanding urethane foam to bind the foundation stones to the liner, lock them in place and prevent water from flowing beneath them.
Photo Credit: ©2001 Dolezal Publishing/Robert J. Dolezal
Waterfall Installation - Step 3
Apply mortar or foam to the foundation stones, then bed the spill stone in place. Check that your spill stone is level and that its height is at least 8 inches below the liner at the top of the stream’s edge.
Photo Credit: ©2001 Dolezal Publishing/Robert J. Dolezal
Waterfall Installation - Step 4
Use mortar or foam to install gate stones to either side of the spill stone that rise above the liner edge and direct water to the center of the stream. Disguise the mortar or foam with decorative cobblestones, bedded in place.
Photo Credit: ©2001 Dolezal Publishing/Robert J. Dolezal
Waterfall Installation - Step 5
Fill the streambed with gravel and cobblestones above and below the waterfall to hold and protect the liner from prolonged exposure to UV-rich sunlight. (Gravel helps reinforce the natural-stream effect.)
Photo Credit: ©2001 Dolezal Publishing/Robert J. Dolezal
