Nusa Dua Beach in Bali has long been a prime destination for tourists, but its dynamic shoreline presents both challenges and opportunities for the construction sector. Recent research led by Ima Nurmalia Permatasari from the Sains Kebumian, Fakultas Ilmu dan Teknologi Kebumian, Institut Teknologi Bandung sheds light on the effectiveness of coastal structures, specifically groins, in combating erosion—a pressing issue for coastal management.
The study, published in ‘Jurnal Teknik Hidraulik’ (Journal of Hydraulic Engineering), examines shoreline changes over a 26-year period, utilizing Landsat imagery and the Modified Normalized Difference Water Index (MNDWI) algorithm. This innovative approach allows researchers to effectively differentiate between land and water features, providing a clearer picture of how coastal interventions are performing.
“Before the construction of groins GA1 and GA2, the beach experienced significant erosion from 1996 to 2002,” Permatasari explains. “After the groins were built in 2003, we observed continuing erosion during both the west and east monsoon seasons, albeit at different rates.” The findings indicate a decline in the coastline of 63.68 meters during the west monsoon and 36.21 meters in the east monsoon, highlighting the ongoing challenges faced by coastal infrastructure.
One of the key insights from the research is the impact of wave energy flux on sediment transport. The east monsoon produced a maximum wave energy flux of 4.9 x 10³ N/s, leading to a more significant longshore sediment transport compared to the west monsoon, which recorded 3.4 x 10³ N/s. “The east monsoon’s powerful wave energy has resulted in a maximum shoreline advance of 65.24 meters, compared to 58.28 meters during the west monsoon,” Permatasari notes, emphasizing the importance of seasonal dynamics in coastal management strategies.
The implications of this research extend beyond academic interest; they have significant commercial ramifications for the construction industry. Understanding the effectiveness of coastal structures like groins can inform future projects, guiding engineers and developers in creating more resilient coastal defenses. As erosion continues to threaten valuable beachfront properties and infrastructure, there is a growing demand for innovative solutions that can withstand the forces of nature.
Moreover, the accuracy of the Coastsat toolkit, validated with an RMSE value of 4.79 meters and an R² of 0.97, demonstrates its potential as a reliable resource for monitoring shoreline changes. This level of precision could enable construction firms to make data-driven decisions, optimizing the design and placement of coastal structures to mitigate erosion effectively.
As climate change exacerbates coastal challenges, the insights provided by Permatasari’s research may pave the way for more sustainable and effective coastal management practices. The construction sector stands to benefit significantly from such advancements, ensuring that developments are not only economically viable but also environmentally responsible.
