SEMARANG, SHOCKS AND STRESS: RESILIENT URBAN SOLUTIONS FOR DROUGHTS, SUBSIDENCE AND FLOODING

Semarang city is the capital of Central Java Province and the fifth largest city in Indonesia. Semarang and 5 other neighboring regions form what is called the Kedungsepur Urban National Strategic Area, placing Semarang in a strategic position. (100RC, 2016).

Semarang is noted to be particularly vulnerable to various hazards, shocks and stresses related to climate change and, as a consequence, physical challenges, such as tidal flooding, land subsidence, sea-water incursion and rising sea levels are taking place frequently. These risks threaten the lower Semarang area, and specifically the competition site. The combination of demographic and environmental characteristics makes the SMA and the competition area a particularly important site for examining local vulnerabilities and adaptability to climate change.

Droughts and lack of water infrastructure

One of the main environmental issues affecting the city of Semarang are droughts, and Kampung Kali Bahru is also under this risk. This issue, coupled with the lack of water supply infrastructure in the neighborhood has led to the proliferation of wells and the over-exploitation of the ground waters. As a result, the space left by sweet water is being replaced by sea water (sea water incursion), with the consequent salinization of the ground waters and the decrease of their quality.

The main water sources in Semarang are (1) water spring with contribution up to 11%, (2) underground water, which supplies up to 19% and (3) surface water that provides up to 70%. However, the quality of these sources is threatened by domestic and non-domestic waste into the river. This river pollution is affecting Semarang water sources. The need of clean water tends to increase along with the rising number of the population. It is estimated that the need of clean water will continue to increase up to 200% in the next 15 years. The city’s water demand is supplied from water sources that are managed by the state-owned water company (PDAM) and non-PDAM parties. The Semarang PDAM manages their water source in a network of pipelines. (100RC, 2016)

Subsidence

As a consequence of this excessive use of the freatic levels and intensive development, the effects of subsidence are affecting the lower area where Kampung Kali Bahru is located with the soil sinking between 5 to 8 cm a year.

In addition excessive underground water extraction creates more problems in water provision because the current pipeline network is still limited.

Flooding

Land subsidence increases the impact of floods. There are two types of flood that occur in Semarang, i.e. the tidal flood which is caused by, among others, the increase of seawater level and land subsidence (causing seawater to flood the coastal area), and flash flood (a sudden flood due to high precipitation that increases the river’s water discharge). There are 21 rivers located in Semarang, creating a high risk of flash flood. Flash flood is also caused by poor drainage infrastructure, environmental degradation in the upstream area, sedimentation in the downstream area and high precipitation. It is important to note that vital assets such as airport, station and port are located in areas that are prone to tidal flood. Seawater level increase is estimated at around 15.5 cm in 2030 and 77.5 cm in 2110. However, land subsidence has a greater impact to the community. It reached 13 cm annually in 2015 and this means that tidal flood would affect around 300,000 people who inhabit the coastal area of Semarang, including the neighbors in Kampung Kali Bahru. Unfortunately, the residents in coastal communities who mainly work as factory workers and fishermen cannot do much, and they basically try to adapt their houses to be higher than ground surface, while some others simply see the flood as a part of normal life considering it happens so often. (100RC, 2016)

To overcome the flooding problems in the area, in 2014 a dike, a retention pond and a pump house were constructed at the mouth of Kali Semarang from which water is pumped out in to the sea. In addition, an earth dike and another pump station have been built in the Kali Bahru river, next to the Jalan RE. Martadinata bridge over Kali Bahru river. Although these two infrastructures have alleviated the rising sea level flooding problem, the subsidence has lowered the ground level almost below sea level. This, coupled with the poor drainage system causes that some parts of the area are constantly flooded, and some others have difficulties to get rid of water after heavy rain events. Therefore, Kampung Kalibaru is still considered as a flood prone area. Moreover, the area faces difficulty in disposing its sewage and rainwater. Currently the sewage produced in the area is treated on-site by individual household septic tanks, however this is not effective in this dense residential areas, as it pollutes the aquifer where the population get their water supply. Communal waste management also contributes to flood disasters. Flash flood and tidal flood are related to the community’s poor attitude towards the environment, such as littering. In Semarang, the municipal government’s waste management service only managed to collect 34% of the total waste in 2013, and left behind the remaining 66%. This shows the poor management of the city waste, considering 50% of the total population was not covered by the service especially in the slum kampung areas, where the low income and vulnerable people live.

RESEARCH AIM

The research aims at proposing innovative solutions to the complex Shock and Stress affecting Semarang and more specifically, alternative and innovative solutions to the challenges of droughts, lack of infrastructure, subsidence and flooding that impact the area of Kampung Kalibaru. Some of the proposed solutions to these challenges include:

  • ‍Solutions for the Heritage - The importance of the identity and heritage elements proposing their integration and rehabilitation and suggesting programs or future uses for the community and/or the city.
  • ‍Solutions to the increase of density - Increasing the density of the existing neighborhood in order to respond to the expected population growth. The increase of density takes into consideration the existing community and kampung housing and proposals have tried to keep the existing as much as possible.
  • ‍Providing adequate housing solutions - Investigating solutions for the existing housing stock as well as for the new housing proposals in order to provide better living environments tackling the environmental challenges.
  • ‍Proposing solutions for a mixed-use neighborhood - Providing a live and work environment where employment opportunities are created and local activities can coexist with city-scale uses. The research aims at exploring the role of the neighborhood in the city due to its strategic location and its relationship with the harbour, the proximity to the train station and the city center, and the very good connectivity of the area with the rest of the city and the airport.
  • ‍Solutions for a resilient mobility - Providing the area and the city with better solutions to solve the mobility of people in order to increase integration and reduce inequalities.