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Assessing the influence of floating constructions on water quality and ecology

Large floating projects have the potential to overcome the challenge of land scarcity in urban areas and offer opportunities for energy and food production, or even for creating sustainable living environments. However, they influence the physical, chemical, biological and ecological characteristics of water bodies. The interaction of the floating platforms affect multiple complex aquatic processes, and the potential (negative/positive) effects are not yet fully understood. Managing entities currently struggle with lack of data and knowledge that can support adequate legislation to regulate future projects.In the Netherlands the development of small scale floating projects is already present for some years (e.g. floating houses, restaurants, houseboats), and more recently several large scale floating photovoltaic plants (FPV) have been realized. Several floating constructions in the Netherlands were considered as case-studies for a data-collection campaign.To obtain data and images from underneath floating buildings, underwater drones were equipped with cameras and sensors. The drones were used in multiple locations to scan for differences in concentrations of basic water quality parameters (e.g. dissolved oxygen, electrical conductivity, algae, light intensity) from underneath/near the floating structures, which were then compared with data from locations far from the influence of the buildings. Continuous data was also collected over several days using multi-parameter water quality sensors permanently installed under floating structures.

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

Urban delta areas require innovative and adaptive urban developments to face problems related with land scarcity and impacts of climate change and flooding. Floating structures offer the flexibility and multi-functionality required to efficiently face these challenges and demands. The impact of these structures on the environment, however, is currently unknown and research on this topic is often disregarded. This knowledge gap creates a difficulty for water authorities and municipalities to create a policy framework, and to regulate and facilitate the development of new projects.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. In this work, a remote controlled underwater drone equipped with water quality sensors and a video camera was used to monitor dissolved oxygen near and under floating structures. The collected data showed that most water quality parameters remain at acceptable levels, indicating that the current small scale floating structures do not have a significant influence on water quality. The underwater footage revealed the existence of a dynamic and diverse aquatic habitat in the vicinity of these structures, showing that floating structures can have a positive effect on the aquatic environment. Future floating structures projects therefore should be encouraged to proceed.

A new submaximal rowing test to predict 2,000-m rowing ergometer performance

The purpose of this study was to assess predictive value of a new submaximal rowing test (SmRT) on 2,000-m ergometer rowing time-trial performance in competitive rowers. In addition, the reliability of the SmRT was investigated. Twenty-four competitive male rowers participated in this study. After determining individual HRmax, all rowers performed an SmRT followed by a 2,000-m rowing ergometer time trial. In addition, the SmRT was performed 4 times (2 days in between) to determine the reliability. The SmRT consists of two 6-minute stages of rowing at 70 and 80% HRmax, followed by a 3-minute stage at 90% HRmax. Power was captured during the 3 stages, and 60 seconds of heart rate recovery (HRR60s) was measured directly after the third stage. Results showed that predictive value of power during the SmRT on 2,000-m rowing time also increased with stages. CVTEE% is 2.4, 1.9, and 1.3%. Pearson correlations (95% confidence interval [95% CI]) were −0.73 (−0.88 to −0.45), −0.80 (−0.94 to −0.67), and −0.93 (−0.97 to −0.84). 2,000-m rowing time and HRR60s showed no relationship. Reliability of power during the SmRT improved with the increasing intensity of the stages. The coefficient of variation (CVTEM%) was 9.2, 5.6, and 0.4%. Intraclass correlation coefficients (ICC) and 95% CI were 0.91 (0.78–0.97), 0.92 (0.81–0.97), and 0.99 (0.97–1.00). The CVTEM% and ICC of HRR60s were 8.1% and 0.93 (0.82–0.98). In conclusion, the data of this study shows that the SmRT is a reliable test that it is able to accurately predict 2,000-m rowing time on an ergometer. The SmRT is a practical and valuable submaximal test for rowers, which can potentially assist with monitoring, fine-tuning and optimizing training prescription in rowers.

Online biomonitoring for continuous water quality control

PowerPoint presentation used during a lecture of Peter van der Maas, professor Sustainable Water Systems at Van Hall Larenstein, on October 8, 2019 at the Wetsus Congress 2019 in Leeuwarden.

Application of a dynamic energy budget model to Mytilus edulis (L.)

Cadmium and copper accumulation in the common mussel Mytilus edulis in the Western Scheldt estuary: a model approach