Feb 28, 2025 04:14:46 pm
Manhajul Islam, S. Ak - BATS Consulting
A fishing boat passes near the giant sea wall project in Cilincing, Jakarta, Thursday (March 15) (Merdeka.com/Iqbal Nugroho).
Climate change and rising sea levels have become serious threats to coastal areas worldwide, including Indonesia. This phenomenon is triggered by global warming, which causes ice to melt at the poles and the thermal expansion of seawater. As a result, many coastal regions face major challenges, including erosion, flash floods, and loss of productive land. These problems not only impact marine and coastal ecosystems but also affect millions of people who rely on fisheries, agriculture, and tourism for their livelihoods.
To address these issues, various strategies have been developed, one of which is the construction of coastal defense infrastructure such as the Giant Sea Wall (GSW). This approach represents a technology-based solution that relies on infrastructure and modern technology to tackle environmental challenges. These structures are designed to block ocean waves and prevent seawater from entering the land, providing immediate protection for coastal areas vulnerable to rising sea levels.
On the other hand, nature-based approaches such as mangrove rehabilitation are gaining increasing attention due to their ability to provide natural protection against erosion and flooding. This approach, known as nature-based solutions (NbS), utilizes natural ecosystems to address environmental challenges sustainably. Mangroves not only serve as natural barriers that absorb wave energy and prevent erosion but also contribute to biodiversity conservation and climate change mitigation by absorbing large amounts of carbon.
Giant Sea Wall
The Giant Sea Wall (GSW) is an artificial structure that serves as a physical barrier against ocean waves and rising sea levels. The main advantages of GSW include:
Instant protection against tidal flooding and rising sea levels, especially in densely populated urban areas.
Can be integrated with urban drainage systems to reduce flood risks caused by runoff and tidal waves.
Allows for infrastructure development and economic expansion in coastal areas by providing greater security against seawater intrusion.
Minimizes the impact of large waves, such as those caused by storms and tsunamis, by absorbing or blocking wave energy before it reaches the shore.
However, due to its artificial nature, several concerns must be considered, such as:
Adverse effects on ocean currents, which may accelerate erosion in other areas and disrupt the natural movement of sediment from inland to shore, affecting nearby properties.
Structural and locational considerations: if the seawall is placed where waves can overtop it, it may lead to sand and soil erosion, weakening the structure.
High construction and maintenance costs. If not properly managed, the seawall can accumulate pollutants such as industrial waste, domestic waste, and plastic debris, contaminating seawater and harming marine life.
Dependence on structural engineering, which is vulnerable to failure if not well maintained.
Damage to marine habitats: the construction of a seawall can destroy coral reefs, seagrass beds, and other critical habitats, leading to a decline in fish, crustacean, mollusk, and other marine populations.
Impact on coastal communities, especially fishermen: the construction of a Giant Sea Wall can disrupt access to the sea and alter the fishing ecosystem. Additionally, the high costs of construction and maintenance can become a financial burden for governments and local communities.
Mangroves
Mangroves are a nature-based solution that acts as a natural barrier against ocean waves and erosion. The primary benefits of mangrove forests include:
Can reduce wave energy by 70-90%, thereby mitigating erosion and flash floods.
Enhances biodiversity by providing habitat for various marine species and migratory birds.
Naturally adapts to climate change, requiring low maintenance costs.
Carbon sequestration: mangrove forests absorb large amounts of carbon, helping to mitigate climate change. Mangroves also improve biodiversity by serving as breeding grounds for various fish and shrimp species.
Opportunities for ecotourism and increased fishery yields.
However, utilizing mangroves for coastal protection has its challenges, such as:
Requires years to grow optimally.
Vulnerable to deforestation due to human activities.
Less effective against extreme waves unless combined with other methods.
Research and Case Studies
Several studies have compared the effectiveness of Giant Sea Walls and mangroves in protecting coastal areas from erosion and flash floods. A study by WWF Indonesia found that a combination of seawalls and mangrove planting provides more optimal coastal protection than relying on just one method. WWF emphasized that mangroves have the advantage of naturally absorbing wave energy, while hard structures like GSW provide additional protection against extreme flooding in the short term.
Giant Sea Wall Project in Jakarta Bay
In Jakarta Bay, the Jakarta Regional Research Council conducted research on the effectiveness of the Giant Sea Wall in protecting the coastal environment. The study found that although the project could reduce the risk of tidal flooding, there were significant ecological impacts on the surrounding marine ecosystem. One key finding was the change in ocean currents, which disrupted the natural sedimentation system, caused erosion in some areas, and increased the risk of waste accumulation around the seawall.
Additionally, the research indicated that the Giant Sea Wall could reduce oxygen levels in the water due to decreased natural circulation. This directly affects fish populations and other marine life, potentially disrupting the livelihoods of local fishermen. As a result, the Jakarta Regional Research Council recommended a more sustainable approach, integrating hard infrastructure with ecosystem-based solutions such as mangrove restoration and the development of environmentally friendly embankments.
Giant Sea Wall in Japan
Japan is one of the countries that has widely implemented Giant Sea Walls, especially after the 2011 tsunami devastated many coastal areas. The Japanese government built approximately 395 km of seawalls at a cost of around 1.35 trillion yen. These structures were designed to protect coastal areas from future large waves.
While providing physical protection, these seawalls also brought various consequences. Some coastal communities reported feeling isolated by the high seawalls, describing them as living in a concrete prison. Additionally, there were concerns that the seawalls provided a false sense of security, reducing public preparedness for tsunamis. Studies also showed that seawall construction altered beach ecosystems and affected surrounding marine life.
"Room for the River" in the Netherlands as a Hybrid Approach to Coastal Protection
The "Room for the River" program in the Netherlands is an innovative project that combines technology-based solutions with nature-based solutions to address flood risks. This program was developed in response to major floods in 1995, which demonstrated that traditional approaches like levee heightening were insufficient. This hybrid approach aims to create more space for water by building floodplains, canals, and natural reservoirs (nature-based solutions), while also utilizing hard infrastructure such as relocated levees (technology-based solutions).
This approach has been implemented in over 30 locations in the Netherlands, including Nijmegen, Kampen, and the Ijssel Delta. In Nijmegen, for example, an additional canal was built to accommodate excess water as a technology-based solution, while in Kampen, flexible dams were used alongside wetland restoration, a nature-based solution. This approach not only reduced flood risks but also helped restore biodiversity and created green spaces beneficial to society.
Conclusion and Recommendations
Although both methods aim to protect coastal areas from the negative impacts of climate change, their approaches differ significantly. The Giant Sea Wall, as a technology-based solution, offers immediate protection but requires high costs and can have significant environmental impacts. Meanwhile, mangroves, as a nature-based solution, provide more sustainable protection with broad ecological benefits but require a long time to develop and may not always be effective against large waves in the short term.
In many cases, the best solution is to combine both approaches in a hybrid strategy, where GSW provides immediate protection against extreme flooding, while mangroves act as a long-term, sustainable solution. With the right strategy, coastal protection can be effectively implemented without compromising ecosystems and community well-being.