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ike Venice and Mexico City, the city of Semarang in Central Java is slowly sinking. Rising sea levels as a result of global warming further add to the burden of these cities. In the year 2100, Semarang may have to deal with the additional drivers of river flooding and unmanaged sediment transport including, among other things, from urban waste that is already affecting coastal cities of Central Java.

In Semarang, everyone loses, but the heaviest burden is placed on local poor communities who are probably uninformed about the fact that their city is sinking due to land subsidence. While infrastructure and housing development continue in many parts of the city, including on land subsidence areas, the future may be overwhelmingly surrounded by stories of not only economic, but also sociocultural losses, including a degree of loss of present civilization.

Studies from scientists, like Gadjah Mada University’s Marfai and others, predict that by 2020, at least 700 hectares will sink by between 50 to 200 centimeters, while another 1,400 hectares of the city are predicted to sink at the depth between a few millimeters to 50 centimeters. Scientists provide different scenarios, but all are convinced that land subsidence is the cause of the tidal floods that inundate many parts of the city.

A total of about 5 percent of the city’s area will likely be inundated, significantly affecting a great deal of population and strategic assets such as seaport infrastructure.

A number of different explanations abound. An educated official who works at the city’s statistics office places the blame on the sedimentation of the city’s rivers. As the depth of the rivers gets shallower, floodwaters simply spill into the neighborhoods of the city. Therefore, local communities, with the support from a series of projects during the last few decades, often ended up elevating village road networks to above the levels of the surrounding houses.

But this explanation doesn’t stand up against the evidence from modern measurements taken using the “stable points network” technique — a process by which measurements are taken by dozens of radar satellite images over a period of time. A group of German and Indonesian scientists, led by Friedrich Kuehn, recently concluded that land-subsidence rates may vary from 1 mm/year to 10 cm/year and even beyond.

Recently, scientists funded by ACCCRN (Asian Cities Climate Change Resilience Network) conducted a vulnerability assessment of Semarang and also arrived at a similar conclusion. In the neighborhood of East Margorejo in Semarang, many houses simply sank. Some houses have sunk into the ground on which they were built by half, while others have nearly disappeared, with only the roof remaining visible.

According to ACCCRN’s vulnerability assessment of Kemijen Village in eastern Semarang, local communities have experience high rates of land subsidence, ranging from about 10 to 15 centimeters annually. For Mrs. Elizabeth, who was born in East Margorejo and lived in the village for 43 years, the problem of the sinking houses is caused by the “rising water” coming from the sea. However, she didn’t make any connections to global warming as some people in the city might have.

We asked a group of boys in the village what they thought caused houses to sink and their answers were similar to Mrs. Elizabeth’s. We further asked the boys: “Which one is true: Is it the sea water [tidal] that is rising or is it the houses that are sinking?” The boys apparently became confused and shrugged their shoulders.

A perception survey recently conducted by Marfai and colleagues among 230 respondents in two selected villages in Semarang in 2008 suggested that 93 percent of the local people were aware that the area is subject to tidal flooding. However, 65 percent of the people suggested that they decided to stay because there were no other alternatives.

Interestingly, 67 percent of the people were aware that land subsidence as the cause of the inundation, 17 percent blamed the poor drainage system of the Semarang River, while another 13 percent suggested rising sea levels were the cause of the problem. The rest had no idea what was going on.

Semarang’s infrastructure, such as permanent housing, grew at an annual rate of 4.4 percent during the last six years. More than 42,000 houses have been built during the 2005-2010 period.

Now, imagine that we are living in 2100. A significant amount of the infrastructure, including community houses built over the last 40 years will be sunken. If the central government and the local government can anticipate rather than react to the changes in the cities’ physical environment, billions of US dollars can be spent smartly and millions of people can be saved from future losses that perpetuate the cycles of poverty.

Can local communities create adaptive mechanisms for problems such as coastal inundation? The ACCCRN project, through the city team and the Semarang Development Planning Board (Bappeda), recently piloted a number of urban intervention activities.

One of the activities was focused on sanitation microfinance through BKM Kemijen, a community-based microfinance institution established in 2000. The sanitation microfinancing efforts aimed to help the most vulnerable persons in the neighborhood, because sanitation is the most pressing issues in terms of vulnerability for households in East Semarang.

Our study suggests that despite limitations in terms of scale, it is clear that community-based microfinance can be an alternative tool not only for reducing household vulnerability to floods and inundation but it can also be used as strategic tool for risk reduction and adaptation elsewhere.

The poor face an urban development dilemma. Elevating their houses has emerged as a real practical need to be resolved, while whatever physical or infrastructure intervention done today will likely become a lost asset tomorrow. In the short to medium term, efforts have been made to guard the city from inundation.

As the city of Venice has started building flood control gates, Semarang has recently started to build polders and recently activated its water pumps to a degree that inundation can be reduced. It is clear that some other policy instruments and interventions must be done to increase future resilience of the city.

Community based microfinancing does not solve all household adaptation problems in a complex urban setting like Semarang. However, given the positive experience of BKM Kemijen in delivering sanitation microfinance services, further research can investigate whether community based financial institution like BKM Kemijen can be used as tools to reduce not only existing urban risk but also future climate risks and vulnerabilities.

At different levels, we probably need a real collective action from all the sinking cities in the world. We look forward to the birth of a “sinking cities network” for the future of our changing planet.

The author, a research fellow based at the Institute of Resource Governance and Social Change (irgsc.org), is a post-doctoral fellow advising documentation work of ACCCRN-Mercy Corps funded by Rockefeller Foundation in Semarang and Bandar Lampung. The opinions expressed are personal.