People whenever they see dolos, they ask what these giant things are? Some people even go to the extent of thinking that dolos is an alien thing.
Tetrapods and Dolos though have been around for decades, but the majority of the people don’t know much about them. Dolos was first invented in South Africa, and both tetrapods and dolos are used as a defence mechanism to protect soil from erosions due to backwater. They are mainly used on the coasts or river banks.
Loose logs and tree branches are often added on the top of interlocking dolos in many banks of rivers and coastline to prevent washouts of riverbanks and restore fish habitat.
In the past two decades, the approach of protecting riverbanks with deeply buried posts of large boulders as riprap has changed. These new approaches are engineered logjams or ELJs and are far less disruptive on the environment.
The twisted protruding stub makes dolos look like a toy jack, is the key feature of dolos. Due to this feature, they can lock each other, and thus they create a stable base wherever they are placed. Tetrapod coastal protection also works with the same ELJ formula.
Biologists believe that the dolos timber system creates submerged structures and fish and wildlife can hide in them, and also, they protect vegetation as well as riverbanks from erosion.
For years, dolos stay in a place, and they don’t get easily displaced as they are interlocked, and therefore, river bank erosion is prevented for a long time. The same way tetrapod coastal erosion is prevented by tetrapod or dolos on the coastlines.
Why Do Some People think Tetrapod and Dolo aren’t a Good Idea?
Though dolos and tetrapods are helpful structures, still there are some criticisms. The first is their shape. Many people think that tetrapods and dolos are a threat to the boaters, swimmers and surfers. Some people criticise that tetrapods and dolos do just the opposite, they make soil erosion as they are disturbing the natural process which shapes the coastal environment. Some criticise tetrapods and dolos for spoiling the natural scenery of the coast. It is also said that due to tetrapods the sand gets pulled away faster compared to natural process.
But whatever the criticism is, the fact is that tetrapods and dolos are very important for defending the coast from soil erosion.