Monitoring the impacts of floating structures on the water quality and ecology using an underwater drone

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Rui P. de Lima, Floris C. Boogaard, Rutger E. de Graaf, Vladislav Sazonov, L. Miguel Dionísio Pires

Friday 3 july 2015

12:15 - 12:30h at Oceania (level 0)

Themes: (T) Managing deltas, (ST) Impacts of urbanization and land reclamation

Parallel session: 15K. Managing deltas - Impacts

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Urban delta areas are facing problems related with land scarcity and are impacted by climate change and flooding. To meet the current demands, innovative and adaptive urban developments are necessary. Floating structures are good examples of the flexibility and multi-functionality required to efficiently face the current challenges for delta cities. They offer flood proof buildings, possibilities for water storage and opportunities for sustainable food and energy production. Their impact on the environment, however, is currently unknown and often disregarded. This knowledge gap creates a difficulty for water authorities and municipalities to create a policy framework, and therefore to regulate and facilitate the development of new floating projects. This frequently hinders these kind of initiatives. Monitoring the effects of floating structures on water quality and ecology has been difficult until now because of the poor accessibility of the water body underneath the structures. A remote controlled underwater drone is used equipped with several water quality sensors and a video camera. The drone is guided under floating structures, where it monitors several water quality parameters such as nitrate, conductivity, ammonium, temperature and dissolved oxygen. As a control, the drone also collected data in the open water zone (unaffected by the blockage caused by the floating body). The results show that the current small scale floating structures do not have a significant influence on water quality. Dissolved oxygen levels under and near floating structures remain at acceptable levels. Furthermore, footage from the video camera revealed a multitude of organisms attached to these structures, in addition to fish swimming underneath them. This shows that floating constructions can have a positive effect on the aquatic environment, by creating new habitats and providing shelter for smaller and juvenile fish. Future floating structures projects therefore should be encouraged to proceed.This information is of great value for many (mega) cities (such as London, New York, Manila) where plans are made to build floating structures in the near future.