Plastic, wood or concrete, which is the best river bank retaining wall material?

Abstract

Erosion is a problem on many streams and rivers. Should land owners decide to protect the stream bank on their property, the construction causes serious disturbance to the aquatic community. Algae periphyton has been used to detennine nutrient limitations and is recommended for pollution monitoring. The periphyton reacts very quickly to changes in the environment, both positively and negatively. An artificial stream was built to test the theory that algal periphyton could demonstrate which material would be the best one to use in construction of river bank retaining walls. The material that produced the algae community with the most biomass would be considered the best. The stream was built with three meanders and samples of each material were hung on these meanders. Samples were taken of the periphyton communities on each of the samples four times. The samples were then dried and cooked in a muffle oven to remove all organic biomass. The results of the samples did not show a significant difference between the three samples. However there was a trend toward a difference between wood and concrete. The test was run for a total of 16 days; this is a short period to analysis the difference completely. The growth on the samples followed a succession, from actuate diatoms (Achnanthidium sp.) to long filaments of centric (Melosira sp.) and pinnate diatoms (Gomphonema sp.) to filamentous greens (Stigeoclonium sp.). The experiment did not show clearly which material is the right one to use, but the information gathered does indicate a need for further testing. The need to protect river banks from eroding is not going to disappear.