Billion-dollar investment needed to save Jakarta from the sea

Witteveen+Bos heads the National Capital Integrated Coastal Development master plan, also known as the Great Sea Wall, to protect Jakarta from disappearing under the sea. Could you tell us more about this project and its urgency?

Indonesia faces a tough decision, namely the medium and long-term flood protection strategy for the metropolitan city of Jakarta. The construction of a sea wall seems likely, but there are discussions on timing, location, and the design life time. However, there is no discussion on the need for immediate protection. Part of this short-term protection is to heighten the existing sea walls with two and a half meter. The construction work has already started and the first districts will be protected this year..However, in some places the city is sinking at a pace of 20-25cm a year. In those parts, the wall will only protect the city for the next 10-15 years and the question is what to do after that. There are now two options on the table: a medium-sized sea wall that will protect the city for 30-40 years (if the sinking is not stopped) or a large sea wall that can protect it for 100 years (with or with sinking). It is a matter of funding, and the discussion continues. We hope to receive the final answer soon because currently there is a Korean and Dutch technical team waiting to detail this sea wall, be it the medium-sized one or the large, original one. The medium-sized one would cost USD6 billion, while the large one would require USD10 billion. Of course, protecting the city is not just about building a wall; there are other expenses and infrastructural necessities to consider as well, such as revamping the drainage system in the city, upgrading the water supply system, cleaning all the water in Jakarta, and more. When we add this all up, the long-term cost could easily be doubled.

What is your assessment of the government’s commitment to the project?

Initially, the Indonesian government wanted to finance the large sea wall with real estate and additional land reclamation. A large island was designed for that, with the profits from developments and investments on that new island planned to finance the sea wall. However, investors in existing islands and some ministries feared that too much real estate would be put on the market and prices and profitability would fall for everyone if such an additional island were to be built. The large new island idea is now off the table and currently NCICD only focuses on the sea wall and other water management related topics. The government still intends to subsidize the flood defenses through real estate development and sales, but now from the ongoing land reclamations in the Bay of Jakarta instead of the new island. Our company is involved in both the sea wall and artificial islands projects. In fact, there is no island around Jakarta where we were not involved in some way. We are specialized in constructing islands and infrastructure in very soft soils, like those in Jakarta Bay. These islands are private developments, led by large investors. Jakarta has an enormous need for housing, so this is a profitable business.

Thus far, the focus has been on crisis water management. How should this be balanced with more long-term solutions?

In water management, it is always important to solve the most pressing and urgent problems first. It is like with Hurricane Harvey, where Texas will also clear the rubble first and look at revitalizing the existing system. After that they will consider to build additional systems and solutions. Coming from a Dutch water management tradition, we always plan and build systems that last 100 years, or at least 50 years. We never build something that will last only 25 years, except for emergency protection purposes. However, I do understand that in Indonesia there is a lack of public money. It is a country that needs a large amount of public money for short-term issues, and spending that much on a long-term solution is difficult.. That said, if the government decides on building the 25-year sea wall, we as engineers will try to stretch the lifetime of that wall as much as possible to make it as effective and sustainable as possible.

There is a debate concerning the wall and the environmental effects as it would change the natural dynamics of water flows. How would you address this criticism, and what are the alternatives?

The critics have a point; all of the water in the entire city of Jakarta and upstream is polluted as there is hardly any wastewater treatment. If we drain that water into reservoirs, we will get black lagoons. With the large sea wall, there will be a large lagoon with poor water quality. Likewise, with a medium or small sea wall, there will be smaller, but numerous polluted reservoirs. Actually, cleaning the water systems should be part of any flood management scenario for Jakarta. Some critics insist on a natural defense for Jakarta, such as repopulating the mangrove swamps and forests along the coast; however, that will not protect Jakarta from three or four meters high seawater. The situation is already out-of-control and the sea is now already 3m above street level. No natural system can protect the city in such circumstances; the sea would simple run right through the mangroves. That means the only other alternative is to abandon Jakarta, which is not a real option. However, there are certain areas where natural solutions can provide protection, and we are also working on those solutions like restoring the mangroves in central Java, for example. Where possible, we go for the soft solution, the natural solution. However, unfortunately for Jakarta, the situation is already out of control, with water overtopping the sea wall at high tide and this cannot be stopped by planting trees. We can only stop that by stopping land subsidence and strong sea defenses. That being said, constructing sea walls takes years. The large outer sea wall will take three years of design and eight years of construction. The planned lifetime of the emergency wall is 10-15 years, while for the large sea wall we already need 11 years before it is finished. We can, therefore, see how urgent the situation is.

What other challenges does Indonesia face in terms of maritime engineering, and can you as a company address these issues?

As an engineering company, we do not only focus on hard engineering such as building ports and bridges, but also look at soft engineering. We do it from a social responsibility perspective, but also because we believe soft solutions have been neglected in the history of civil engineering and that the consequences of that have started catching up with us. The mangrove project in Central Java is an example of our attention for so-called Building with Nature. We are not only restoring mangroves there, but also giving economic benefits for the local communities, who can develop fishing, create fishponds, and so on. We design the mangroves in such a way that they catch sediment so the land grows again and expands: smart mangroves, basically. Another project that we are doing is looking at how to protect coral habitats. There is a great deal of tourism development on small, beautiful coral islands, though this is also destroying the natural habitat. These are sensitive areas, and a large number of tourists mean a great deal of damage. We have been doing tests on coral restoration and beach protection, trying to merge tourism with the strengthening of ecosystems. We will try to expand the first successful trial to a larger project that will involve the Indonesian government and research institutes to roll this out on a larger scale. This is not a commercial enterprise for us; it is purely from a CSR perspective. However, it is also important for us in terms of learning more about green engineering and also benefiting Indonesia and the planet in terms of saving and restoring coral habitats and coral islands. We are testing several methods to determine which works fastest and most effectively, in terms of results, manpower, cost, and so on.