BEGINNER’S GUIDE TO BUILDING STREAMS AND WATERFALLS: Part 1

Getting the size and width and length in the right proportion to the whole water garden.

A pool with a backdrop of a rock bank with a stream or waterfall tumbling down it makes a perfect scene. The two go together like strawberries and cream. The rock bank does not have to be completely rock andThis stream by Peter May seems to be fed by the Lion mask but in fact there is a separate feed to the stream. stone. It can merely be suggested. In fact it can be lawn or ground cover with only rock showing around the cleft of the stream and where there is a waterfall drop. In more modern scenarios the rill and the ‘mirror waterfall’ from a letterbox or chute seem to dominate.
Modern or not, a stream or waterfall should not be disproportionately large in relation to the pool. When you switch on the submersible water pump in the pool to start a stream running, that stream needs at least ½ inch (10cm) extra water depth added to its surface to get the water flowing effectively. Not only this, there is a backlog of water that seems to get hidden in the system. Added together, this can mean a considerable loss of water from the pool once the stream is in full flood. The marginal plants in particular cannot stand the resultant radical rise and fall in water level if too much water is taken out every time the stream is started.

This stream is cut into mounded soil. Rockwwork is kept to a minimum by making it disappear under the turf In the natural scene, the choice of where the stream will run is generally motivated by the lie of the land and this also helps locate the pool. Many people use the mound of soilNatural Abstraction by Designscape UK from the excavation of the pool to run the stream down. This will need very careful consolidation as the soil excavated from the ground will at least double in volume and takes at least a year to become compressed to its original volume again. With regard to the waterfall at the point of entry to the pool, this will seem a lot more in keeping with the scene if the watercourse enters at point where the pool has a sharp outward curve like the ‘v’ to a delta. Also the stream should be cut into a cleft in the terrain as though it has eroded its own path over many years.
The width of the stream is also relevant to the volume of water the pump can deliver to the head of the waterfall. Estimate roughly for 60 galls (300 litres) per hour per inch of sill or waterfall width (say 100 litres per cm) that can be delivered to the height you require. All the pumps carry performance figures and charts on their boxes and in the promotional material on the displays. So bear the waterfall width in mind in relation to the size of the pool.

STREAMS WITHOUT A POND

A typical old fashioned style of pump with float switch.Now having said all that, there is currently a fashion, particularly in the USA, for having a stream without a pond. This is considered safer and it is without the fuss and bother of having to keep a pond healthy and clean. The sound of moving water can be had with the water disappearing into a hidden reservoir. As you can tell if you have read most of the preceding article that there needs to be a substantial reservoir of water to provide enough flow for the whole stream and to maintain that flow. Taking into account the fact that streams and waterfalls evapourate water and have a certain propensity for leaking, then it always wise to have a pump that sits in the sump that is fitted with a float switch that automatically turns the pump off when it is in danger of running dry. This also guards against the possibility of any debris building up the stream causing it to overflow and empty the sump and in turn burning out the pump. I once had a client that had a golden retriever that used to like lying in the stream I built on a hot day, letting the cool water billow over her – and out over the edge of the stream onto the lawn. It was two burnt out pumps and two visits from me before we cottoned on to this problem. For the subtle details of what to look for in pumps with float switches ( and we are talking serious professional installations here) look at http://www.sump-pump-info.com/float-switches.html.