Notes on stream water feature
The key with building a stream feature is to make it look natural. One of the mistakes made in building a stream in a garden setting is that cement and concrete is used to set the rocks in place and this created an unnatural looking effect. It is best to dig out the channel and then to place the rocks directly on the liner in the channel in a natural manner. Then to back fill the gaps under the rocks with dry mic cement and shard sand 1part cement 4 parts cement. Then cover and fill in the gaps between the rocks with a gravel or small chippings from the rocks. This has the effect of of keeping the stream looking natural and diverts the water coming down the stream over the rocks for a better effect.
The other key area is to make sure the sump which holds the water the stream uses is large enough to allow the water to be pumped up to the head of the stream and to travel back to the sump before it becomes empty
This is a link to more notes on creating a garden stream water feature click here