Nations worldwide are striving to meet the climate goals set forth by the Paris Agreement and reduce greenhouse gas emissions, with offshore wind farms (OWFs) playing a crucial role. However, OWF construction generates underwater noise from impact piling, which is harmful to marine life. This study examines the effects of PULSE – a novel mitigation measure acting as a spring-damper system between the hydraulic hammer and monopile – on underwater noise and its interaction with air-bubble curtains. Using the semi-analytical SILENCE model, the complete pile-water-soil system is simulated to evaluate noise levels, with the model’s predictions compared to field data from a recent German project. Results show that PULSE effectively reduces both Sound Exposure Level (SEL) and Peak Sound Level (Lpeak) by shifting acoustic energy from higher to lower frequencies. When combined with air-bubble curtain configurations, noise reductions are greater, but the effectiveness of PULSE diminishes. Consequently, the individual performance of PULSE and air-bubble curtains cannot be linearly added to predict their combined effectiveness. In conclusion, while PULSE effectively mitigates underwater noise, its combined use with air-bubble curtains impacts overall mitigation efficiency and requires careful evaluation. ... Read more

The research question addressed in this study is ”To what extent does the presence of a cloud forest canopy impact the Mestelá River catchment and how will this affect the various involved stakeholders?”. The study aims to investigate the importance of cloud forests in the Mestelá River catchment, Alta Verapaz, Guatemala, related to water security and the social impact of cloud forest conservation and management. The research methods used in this study were a combination of quantitative and qualitative methods.

Cloud forests play a vital role in regulating water flow in catchments. The Mestelá River catchment, where the NGO Community Cloud Forest Conservation (CCFC) is situated, is the focus of this research. The project’s primary aim was to establish a long-term canopy setup, ensuring future data collection. The project’s scope encompasses a range of methodologies, including the installation of a long-term measurement station in the canopy, computation of the Mestelá River discharge, the development of a rating curve, and the utilisation of a FLEX-Topo model to simulate the hydrological cycle in the catchment. Additionally, a stakeholder management analysis was conducted to understand the complex impact of cloud forests (conservation) on various stakeholders.

The study did not explicitly formulate any hypotheses, but the findings provide evidence for the impact of cloud forest canopies on river catchments and discharge. The study also has limitations, including the small sample size and the lack of long-term data. However, the study provides valuable insights into the importance of cloud forest ecosystems for water security and the social impact of cloud forest conservation and management. The stakeholder analysis reveals that for CCFC two methods of advocacy can be used. Whilst the CCFC is effective in bottom-up engagement with the community, in addition, a strip for small children was constructed. For top-down advocacy, using the FLEX-Topo
model for visualising water security in combination with cloud forest protection holds promise.

The implications of this work are substantial for cloud forest conservation and associated ecosystems. The findings offer valuable insights for developing effective conservation strategies that consider the canopy’s impact on the catchment and its stakeholders. It is important to note that the FLEX-Topo model is currently conceptual and requires further refinement and detail for the Mestelá River catchment. Nevertheless, this study contributes significantly to the understanding of cloud forest ecosystems and offers practical and theoretical applications for future research and conservation efforts. ... Read more