Frequently Asked Questions about NCICD
Justification of the NCICD-programme
In 2007 catastrophic floods hit Jakarta, taking the lives of 76 people and displacing over half a million people. The government of the Netherlands offered help to Indonesia to take measures. First the current sea wall was strengthened, and then a strategy was developed: the Jakarta Coastal Defence Strategy (JCDS). The strategy is now further developed in the National Capital Integrated Coastal Developmentprogramme (NCICD).
If nothing is done, Jakarta will keep sinking. In time the whole coastal zone of Jakarta will sink further under sea level. Rivers cannot flow naturally into the sea anymore and frequent flooding will occur inNorth Jakarta. Due to the bad water quality of the rivers, more diseases are expected as a result of flooding. In 2020 approximately 4,5 million people could have lost their homes and 103 billion USD worth of land is at risk to be lost permanently to the sea.
All people living in the coastal zone of North-Jakarta will benefit from this programme. Although the main goal of NCICD is to improve the safety of the people living in the coastal zone of North-Jakarta from flooding by the sea, the programme follows an integrated approach to achieve a combined set of goals:
- Creating flood safety for people in North-Jakarta
- Water quality improvement of the rivers and the Bay of Jakarta (less chance on disease during flooding)
- Revitalization of North Jakarta (recreation areas, social housing, outplacing industries)
- Creating economic development (job opportunities, increase tourism to Jakarta and pulau seribu, fishery sector, improving transport & logistics)
- Environmental restoration of Jakarta Bay
Above mentioned goals are all contributing to improvement of the living conditions for the people in North Jakarta. As this is a huge program, this can only be achieved by integrated and strong management and with support from the private sector.
Raising the current sea wall is providing sufficient protection from floods by the sea on the short term (2025). However, landsubsidence is likely to continue for some time. For the longer term raising the current sea walland river dikes again is dangerous. With current land subsidence rates,the current sea wall and river dikes will need to hold back a wall of 5 metres of water in only 25 years. If such a dike would break, the consequences are truly disastrous. In addition, to construct such a giant dike on the location of the current sea wall will still require relocation of many houses, people and infrastructure such as pumping houses and bridges.
Yes, several alternatives have been studied during the preparation of the Master Plan. One alternative is to turn the coastal zone of North-Jakarta into one large waduk. However, it is not possible to find this capacity onshore in the existing city as it would require resettlement of a great many people (approximately 1 million people).
As inundation of the current sea wall is already imminent, the work on the reinforcement of this dike has now started (Stage A). After finalisation the Stage A, the current sea wall provides protection up to 2025 and can be raised slightly to protect until 2030.
Due to the effects of subsidence, the sea wall has to be closed between 2025 and 2030. Around that time rivers will have to stop discharging to sea. Construction of the Sea Wall is expected to take 7 years, meaning that construction of the outer sea wall need to start in 2018.
The Outer Sea Wall will be a very robust sea wall. The Outer Sea Wall is designed to withstand sea conditions with a probability of 1 in 10.000 years. Also a possible tsunami was taken into account in its design. The Great Waduk and the pumping station are designed for rainfall and river discharges with a probability of 1 in 100 years.
Impact of Land Subsidence
Subsidence is the process of the soil in the city going down. In Jakarta this process goes very fast: up to 14 centimetres a year depending on the location.Subsidence can have several causes. The most important cause in Jakarta is groundwater extraction. As groundwater is extracted in huge quantities, the pressure in the soil goes down, leading to subsidence. Only when groundwater extraction is limited or stopped, this process could be slowed or stopped. If not, the city may go down several metres more in the coming 50 years.
Diversion of water upstream is no real alternative for floods in the coastal or downstream area. The rain that falls in Jakarta itself will still have to be pumped into Jakarta Bay. Diversion of water upstream can help only to reduce the volume of the reservoir needed, but is never an alternative.
The 17 islands or land reclamations planned in the Bay of Jakarta are not part of NCICD, but shall be coordinated for spatial planning purposes. DKI is also cross-subsidizing pumping stations and social housing from revenues of the constructed islands.
Impact on Fisheries
Closing the Bay of Jakarta will have three impacts on fisheries:
- the water quality outside the Bay of Jakarta will improve as pollution will be contained in the reservoir;
- loss of fishing grounds inside the Bay. On the loss of fishing grounds in the Bay one can argue that this area is already so polluted that consuming fish from this area is a health risk;
- Ships will have to pass a lock in the sea wall. For the local fisherman who goes to sea on a daily basis, these locks will be considered to be a hindrance. For those local fishermen new ports and communities are reserved at the wings of the Outer Sea Wall. The costs are already covered in the business case.
The main environmental impacts have been evaluated and published in an environmental assessment. This document is currently converted into a KHLS (strategic environmental assessment). The main issues are known and need to be mitigated. Additional research will provide more details, but most likely will not lead to a fundamentally different assessment of the environmental situation.
The water quality in Jakarta Bay and in the 13 rivers currently is very bad, with low oxygen concentrations. Waste water and solid waste is still entering the bay untreated, where it is diluted in the sea. Consequently the sediment in the bay is already contaminated with organic and heavy metal contaminants.
Water treatment is of utmost importance to solve the water quality issues in Jakarta Bay. We consider this an important no-regret measure as improving water quality is beneficial to the environment and to human health.
The salt water based marine life in the bay will disappear after closure. Larger migratory fish species will escape along the changing salt gradient during construction and finally disappear when the sea wall is closed. The environmental quality in the fresh water lake will to a large degree depend on the progress in the implementation of a water treatment system. This requires further study in the planning & design phase.
Closing off Jakarta Bay will have significant impacts. Initially, these effects will be negative as the current salt water based environmental system will change into a fresh water system. This is being addressed in the KLHS (environmental strategic assessment).
Facts and Numbers
NCICD combines the result of 7 years of joint Indonesian an Netherlands research. The technical documentation covers several thousands of pages and more than 10 million euro has been spent. All available documentation in Indonesia has been evaluated. The technical basis for the Master Plan is sound: the problem of subsidence is well understood, rates of subsidence are clear, we know the sea levels over time, we understand the hydraulic system of the National Capital and have good understanding of the water quality situation and the impact on the project. We also understand the major socio-economic and environmental impacts. The conclusions in the NCICD Master plan on problems and solutions therefore have a strong technical basis.
The total length of the outer sea wall will be 25 kilometres. The area of the great Waduk will be at minimum 7,500 hectares. It needs to be this big to be able to temporarily retain the water from the 13 rivers of Jakarta.
Keeping the water level in the retention lake between its design limits requires the largest pumps in the world. The total pumping capacity of these pumps will be about 730m3 per second. With this capacity the maximum water level fluctuation in the lake is 2.5 metres.
The Outer Sea Wall is located far into sea. The maximum water depth in which it will be constructed is 16 metres and the sea wall will extent 7.7 metres above sea level. The Giant Sea Wall will be largely build form sand, possibly complemented with caissons. Made of sand, the base of the sea wall will be 380 metres wide at its deepest point. Construction methods will be further detailed during the planning and design phase.
NCICD is unique as nowhere in the world a sea wall of this scale is combined with the development of a complete coastal city. The combination between a sea wall and retention lake does exist in other countries. The Afsluitdijk in the Netherlands and the Saemangeum Sea Wall in South Korea most closely resemble the Giant Sea Wall in size. Most challenging is managing the project in an integrated way. That is why a special organization unit (dedicated authority) is needed.
There will be an initial investment by the Govt to guarantee safety in time. Over time, costs can be recovered by allowing income generating activities such as (additional) land reclamation, toll road, etc.