One rock goes where each potato has landed. Water, or the lack of it, is an essential part of any landscape. Water delights the eye whether still or moving. Moving water provides a number of interesting sounds for the ear. Three of these are basic.
Shallow water moving at a moderate rate over small stones creates a sibilant whisper.
Deeper water moving rapidly over larger stones roars and pulses. Heard at a slight distance, the effect is of someone speaking quietly, but not understood. It is this sound that led primitive man to believe that there were spirits in water. Unless the garden is to he very modern and rigidly planned with an abstract fountain, it is best to keep the source of the water on or near the ground. Few things are uglier than a mound of rockwork that has no association with its surroundings.