Summary
In 2013, Alberta experienced a heavy rainfall that was considered the worst in its history, with deaths, over 100,000 people displaced and a total damage of over C$5 billion.
After this flood, the riparian area had its importance increased because of the protection against flood damages. Then, a comprehensive survey based on FREP protocol about the health of riparian area began in 2015 and this data was used in this work to evidence what causes are related to an unhealthy riparian area and what is the contribution of conventional treatments.
The results showed that plants with deep root systems are essential to have properly functioning riparian areas. It is also possible to understand that natural damages may eliminate deep-rooted plants from banks and riparian area, however, the effect on riparian functionality is less severe than when they are suppressed by human activities.
Moreover, human activities such as grazing, agriculture, recreation as well as conventional treatments on streambanks affect the riparian area and its functionality.
From the riparian functionality perspective, conventional treatment represents only a static feature which physically retains a bank without interaction with the surroundings. Due to that, those treatments are subjected to new erosive processes and cannot provide all the benefits of a riparian zone which is composed mostly of deep-rooted plants.Therefore, conventional treatment can be seen as an anthropic damage rather than a proper treatment for streambank failures.
Plants or bioengineering does not replace conventional treatment when this is required because there are clear strength limitations for plants when compared to steel. However, due to liability issues, managers, contractors and designers opt for conventional treatment over bioengineering even when it is not necessary. This makes conventional treatments, causing environmental loss, more a convenient evil than a necessary evil.
Finally, public policies and treatment for streambank failures need to be upgraded, promoting more riparian planning and looking at plants as a construction material for infrastructure works.
After this flood, the riparian area had its importance increased because of the protection against flood damages. Then, a comprehensive survey based on FREP protocol about the health of riparian area began in 2015 and this data was used in this work to evidence what causes are related to an unhealthy riparian area and what is the contribution of conventional treatments.
The results showed that plants with deep root systems are essential to have properly functioning riparian areas. It is also possible to understand that natural damages may eliminate deep-rooted plants from banks and riparian area, however, the effect on riparian functionality is less severe than when they are suppressed by human activities.
Moreover, human activities such as grazing, agriculture, recreation as well as conventional treatments on streambanks affect the riparian area and its functionality.
From the riparian functionality perspective, conventional treatment represents only a static feature which physically retains a bank without interaction with the surroundings. Due to that, those treatments are subjected to new erosive processes and cannot provide all the benefits of a riparian zone which is composed mostly of deep-rooted plants.Therefore, conventional treatment can be seen as an anthropic damage rather than a proper treatment for streambank failures.
Plants or bioengineering does not replace conventional treatment when this is required because there are clear strength limitations for plants when compared to steel. However, due to liability issues, managers, contractors and designers opt for conventional treatment over bioengineering even when it is not necessary. This makes conventional treatments, causing environmental loss, more a convenient evil than a necessary evil.
Finally, public policies and treatment for streambank failures need to be upgraded, promoting more riparian planning and looking at plants as a construction material for infrastructure works.
WHAT IS RIPARIAN AREA?
Protection against floodingRiparian areas are the areas surrounding rivers, creeks and streams. They include riverbanks and floodplains and can range from a few meters to several hundred meters in size. The soil coverage varies from grass up to deep-rooted plants such as willow bushes.
Downstream flooding can be reduced by riparian area vegetation. As floodwater flows through a vegetated area, the plants resist the flow and dissipate the energy, increasing the time available for water to infiltrate into the soil and be stored for use by plants. |