Pekalongan flood risk and impact assessment predicts 90% of the city will be inundated by 2035: how is climate change impacting Indonesia?

Source(s): Zurich Flood Resilience Alliance

By Denia Syam and Yoko Okura

As part of the Zurich Flood Resilience Alliance Mercy Corps is working with the Pekalongan City and Regency in Indonesia to to promote evidence-based policy making and program development. In this blog we share findings from a Flood Risk and Impact Assessment of the Kupang Watershed, and how we are using these to support governance of flood risk.

Climate variability is leading to increased flood risk in the Kupang Watershed

1.2 million people live in the densely populated Greater Pekalongan Area in Indonesia, comprised of Pekalongan City and Regency. Located in a busy corridor on the North Coast of Java, the area plays a pivotal role as one of the main centers of economy, industry, trade, and services in the region. The Kupang Watershed is an important water source that runs through both Pekalongan City and Regency, and provides water for households, industries, and public facilities. 

Ground water extraction has increased in recent years leading to rapid land subsidence causing both the city and regency to seek alternative water sources. Moreover, the Kupang Watershed has long suffered from extreme flood events, and changes in climate variability is increasing the risk of flooding. Climate change and flooding will not only lead to devastation of lives and livelihoods, but also impact Pekalongan’s longer term water security by creating significant demand for alternative water resources. 

Providing governments with evidence on climate risk and impact

Through the Zurich Flood Resilience Alliance program, Mercy Corps Indonesia is working with the Pekalongan City and Regency governments to promote evidence-based policy making and program development. We are doing this by conducting a Flood Risk and Impact Assessment of the Kupang Watershed with three leading research institutions (Agromet; Center for Coastal and Marine Resources Studies at Institut Pertanian Bogor University; and the Center for Coastal Disaster Mitigation and Rehabilitation Studies at Diponegoro University), and co-developing programs with the government that will address the identified risks and impacts. 

The assessment provides insight into how poorly planned development activities like groundwater dependence for water supply in downstream areas, exacerbates flood impacts, and causes economic and non-economic losses of for example biodiversity, assets, cultural heritage, and health. It also sheds light on how current development practices in the downstream and coastal areas are also intensifying the impact of flooding within the city. Lack of understanding by policy makers on the connections between land subsidence and flooding has led to activities that exacerbate the impacts of climate change.

With increasing exposure of Pekalongan to extreme weather events, it is now more important than ever to design and implement programs that address compounded risks from poorly planned development activities, water over-extraction and climate change. This kind of evidence is also important to support governments to take a landscape perspective and transboundary governance approach for watershed and coastal management. Recognizing the connections of actions in each of the administrative areas, shown through evidence, will help the city and regency to together develop program activities that can address needs and challenges.

Land subsidence and extreme rainfall will increase flooding in Pekalongan

Initial findings from our climate modelling and flood hazard analysis show that the Kupang Watershed will experience more frequent and intense extreme rainfall events in the near future, between 2020-2035. Moreover, our spatial analysis points to the high rate of land subsidence as the main contributing factor to flood inundation - lower land levels exacerbate exposure to flooding. Chronic and irreversible impacts of flooding are already being observed. The rapid and significant rate of subsidence, as much as 15-34cm in 2019, has led to some areas of the coast turning into water basins with the land below sea level. 

Land subsidence and the increasing intensity and frequency of rainfall, compounded with tidal and sea water intrusion, has led to severe tidal flooding in Pekalongan. In fact, since 2011, nearly 700 hectares of land, which was previously used for farming and aquaculture, has now been permanently inundated. Our research predicts that by 2035, a worrying 90 percent of Pekalongan City and a major portion of the Pekalongan Regency coastal area will be inundated – totaling around 5,200-5,700 hectares of land. The extreme rainfall will also increase flood risk in the midstream area of the Kupang Watershed, where key industries are located.  

This has serious implications for people’s lives and livelihoods. For example, the percent of residential areas projected to be impacted by flooding in Pekalongan City is estimated to increase 100 times, from 0.5 percent in 2020 to 51 percent in 2035. The 1,526 hectares predicted to face permanent inundation by 2035 in the Greater Pekalongan Area, are currently utilized for rice fields, aquaculture ponds and residential area. Annual population growth of the area of around 1% will continue to increase the communities’ demand for water and food. 

These alarming predictions leave the Pekalongan regency government and residence with some stark choices on how to deal with the loss of productive land and assets.

Managing flood risks through transboundary water resource management approaches

Addressing flood risk requires stakeholders to consider the current challenges as a comprehensive and cross-boundary water resource management issue. Since the Kupang Watershed runs through both the Pekalongan City and Regency, the two administratively separate governments need to work together to manage the drivers and effects of flooding. 

Pekalongan City does not have reliable surface water sources because the rivers are highly polluted, and the city relies heavily on spring water in the Regency for potable water. Development activities that occur in the upstream and midstream areas in the Regency impact water flows and quality for downstream areas of the City. 

Our research shows that flooding and water supply are connected and that land subsidence is occurring due to lack of clean water services driving over-extraction of groundwater by communities and businesses. This significant rate of land subsidence in turn leads to increased impacts from coastal and tidal flooding, and the emergence of permanently inundated areas. As urgency to address this issue increases, we are facilitating discussions with both governments to develop actionable solutions.

Coordination between different agencies and administrative structures require significant investment. Flood resilience requires consideration and alignment of three main policy frameworks (development, spatial, and sectoral plans) to ensure that these do not have unintended negative consequences for one another.  

Following consultations and workshops with multiple government actors at the local, provincial, and national levels, including organizations such as the local disaster management agency, provincial public works and spatial planning agencies, and the National Development Planning Agency, we have refined possible solutions to address flood risk and water management in Pekalongan. 

Mercy Corps will support the Pekalongan government approach to flood risk under six identified categories:

  1. Water resource strategy to reduce the rate of land subsidence.
  2. Infrastructure resilience strategy to reduce the impact of destructive water force in downstream and coastal areas, and adapt to irreversible losses.
  3. Environmental health strategy to improve the quality of environmental sanitation and ecological function of the watershed.
  4. Social and economic systems resilience strategy for affected communities, as a part of the coastal and fisheries sector strategy.
  5. Regional development strategy in reducing risks to spatial planning and to promote better spatial management of watershed.
  6. Disaster management strategy, including contingency and emergency response

The selection of specific interventions under the six categories will require a detailed analysis of impact, costs and anticipated benefits. Moving prioritized interventions into implementation will require consultations with diverse investors and exploration of different public and private financial instruments to cover the costs of diverse flood protection mechanisms that strengthen social, economic, and environmental systems.

What the future looks like for Pekalongan 

The selected interventions will be embedded in existing policy mechanisms to ensure sustainability of the work beyond our program. With the Greater Pekalongan Area selected as one of the priority areas for the National Action Plan on Climate Change Adaptation, there is momentum and high political interest to address the six categories.  We will continue to work collaboratively with multi-level government entities to ensure that evidence based, actionable solutions that comprehensively consider flood resilience are designed and implemented.

Pekalongan serves as an example for many coastal cities globally which will face severe flood impacts under global climate change scenarios. The full package of intervention options provided for Pekalongan are beyond the financial capacity of any single program or city to finance. City and country governments will need to make hard choices about how and where to invest, ranging between hard infrastructure and softer green interventions. 

The reality is that some communities and settlements will have little choice other than to move away from permanently inundated areas. Decisions on who will be relocated, when and how will require evidence, cooperation, and transparency in decision making and planning. Assessments like our climate analysis can provide evidence for decision makers globally to better understand current and future risks, and enable evidence-based policy and program development that sees climate financing as an investment for sustainable solutions.

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Hazards Flood
Country and region Indonesia
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