Design a Natural Stream Bed: Erosion and Deposition

Designing a small stream for a home garden can be a joy and a challenge. The joy is obvious: the sound and look of running water are beautiful, and creeks attract wildlife to the garden. However, to design a water feature that works well in your garden, you need to understand the many ways that rivers and streams shape themselves in nature and design your stream accordingly.

Natural Stream Bed and Floodplain Features

A natural stream bed is full of natural variation. This is one of the reasons that creek areas are so diverse. They are full of diverse floodplain and marshland habitats. Some plants need to live near creeks in order to get the water and nutrients that they need, while others thrive in recently flooded area. This diversity of plant life brings a diversity of wildlife to the floodplain.

Natural streams also have areas of fast and slow-moving water. These are called riffles and pools. Gradually, moving water will shape the landscape into riffles and pools, providing quiet hiding places for fish and fast-moving, oxygen-rich water.

Erosion and Deposition Zones in a Natural River Bed

Another major element of a natural creek bed is the presence of zones of erosion and deposition. Streams move material along their beds, particularly during flood conditions. Some of this material is fine and moves along in the water column. This can be deposited on stream banks when it floods or in areas that have slow-moving water. Gradually, these areas will get filled in by fine sediment and plants will colonize these little curves in the bank.

Other parts of the creek will get eroded over time or during a major flood event. If your creek is connected to a natural drainage system or happens to be a side channel of a natural creek, it will flood sometimes. These floods will move gravel and hand-sized rocks called cobbles to the end of the creek. All water features move fine sediment around the creek constantly, and some areas of a natural creek bank will become eroded. Plants and soil may even drop into the creek as the banks erode.

Design Elements to Help Create a Natural Water Feature

Are natural erosion and depositional processes something to worry about in your backyard water feature? Not if you plan for them. To design a stream that works with natural erosion and deposition, do the following:

• Give the stream space for natural erosion and deposition to occur.
• If you cannot allow the stream to move, add cobbles or larger rocks along the bank to reduce erosion.
• Beginby placing cobbles and gravel for the stream bed, but accept that these rocks will move within the stream bed over time.
• Plant deep-rooted plants to reduce bank erosion. Nature does this and you can do it on your own creek too.

Creating a natural style of creek demands that you become more flexible with your approach to gardening. If you are willing to allow a water feature to change over time, then designing a backyard stream to accommodate natural erosion and deposition will allow you to create a diverse and ever-changing ecosystem in your garden.