Grading and infrastructure
The next priority is dealing with groundwater, drainage, elevation and stable soil issues. Ponds are often designed and built in lowlands. This would seem to be the logical location, as surface water can be used to maintain pond water levels. However, with surface runoff comes organic debris including, fertilizers, herbicides and pesticides, which can wreak havoc within a water feature.
In nature, ponds in low areas tend to fill in over a period of time. They may start off deep, but slowly become shallower until thick aquatic vegetation eventually spreads over the entire pond surface, ultimately turning it into a wetland or marsh.
When designing a water feature, a landscaper has the opportunity to place the feature and shape the surrounding land in order to avoid this natural filling-in process.
Once the water feature’s location, size and orientation have been determined, an under liner drainage system should be installed in situations where the surrounding land is higher than the pond’s water level. The primary reason for this type of drain system is to relieve any groundwater pressure from lifting the liner. This problem occurs most often when there is underground water in the surrounding hillsides and gravity is trying to push it downhill creating hydraulic pressure.
Systems that do not employ under liner drainage have a greater risk of developing what are called ‘hippos,’ which occurs when the liner is lifted off the bottom of the pond. In these situations, a combination of events typically occur. Not only is water pressure pushing the liner upward, but a small air pocket is typically formed in the uplifted liner, which then allows for an increase in water degassing. This process continues until the liner is actually sticking out of the pond surface by several inches.
Commercial water features
Rather than creating ‘destinations,’ commercial clients are more interested in creating a ‘wow’ factor. The goal for these projects—for example, an entrance to a business or a new subdivision—is to draw the public in by creating a dramatic visual and audible presence that is easily noticed.
For many commercial projects, the feature’s realism or authenticity may take a backseat to visual stimulation or awareness. An abundance of flowing water can therefore be a necessity for the feature to fulfil its purpose—especially for people passing via car who only have seconds to see and recognize what they are looking at.
Common commercial water feature mistakes
- The waterfall structure is mounded in an unrealistic manner, similar to a volcano, without any apparent reason other than a hill being present at the location. To make a feature convey realism, sufficient effort should be made to taper the waterfall structure and use proper proportions of rock and plant material.
- The water is not easily visible from the primary viewing areas. This can be due to insufficient flow, poor selection of weirs and rocks within the watercourse or simply because the flowing water is contained in steep-sided waterways. In this case, strong shadows are cast and cause the sun to reflect off the moving water.
- The water is ejected out the top of a hill or mountain, something rarely seen in natural waterfalls.
In nature, water is rarely the highest object, nor is it often seen pouring from the top of a rock ledge. When trying to create a realistic or authentic-looking water feature, it is important the apparent source of the water is not disclosed. A client or visitor to a water feature should not be able to easily see where the water is coming from. Keep in mind a water source looks much more natural when it is seeping through cracks or fissures in rocks, welling up from underground or around the base of trees, rather than coming out the top of a mound of rocks or shooting out of a pipe.
Hiding the actual water source can be accomplished by discharging it around a corner in the stream or having it emerge from under a larger rock, collection of rocks or grouping of plants. When building a longer stream, it is more convincing to inject water at various locations to give the impression the stream is building in volume as it descends a hillside.
