This study explores urbanization and flood events in the northern coast of Central Java with river basin as its unit of analysis. Two types of analysis were applied (i.e., spatial data and non-spatial data analysis) at four river basin areas in Central Java—Indonesia. The spatial analysis is focused on the assessment of LULC change in 2009–2018 based on Landsat Imagery. The non-spatial data (i.e., rural-urban classification and flood events) were overlaid with results of spatial data analyses. Our findings show that urbanization, as indicated by the growth rate of built-up areas, is very significant. Notable exposure to flood has taken place in the urban and potentially urban areas. The emerging discussion indicates that river basins possess dual spatial identity in the urban system (policy- and land-use-related). Proper land use planning and control is an essential instrument to safeguard urban areas (such as the case study area) and the entire island of Java in Indonesia. More attention should be put upon the river basin areas in designing eco-based approach to tackle the urban flood crises. In this case, the role of governance in flood management is crucial.

Indonesia, as an archipelagic nation, has about 150 million people (60%) living in coastal areas. Such communities are increasingly vulnerable to the effects of change, in the form of sea level rise and stronger, more intense storms. Population growth in coastal areas will also increase the disaster risk mainly because of climate change-related effects such as flooding, droughts, and tidal floods. This study examines the dynamic changes of urban population and urban villages in three decadal periods, from 1990, 2000, to 2010. To highlight different disasters that are increasingly tied to climate change, the analysis was conducted in the northern coastal area of Central Java province using village potential (PODES) data, which are routinely collected by the government. Results show that about 41% of people in Central Java province live in the northern coastal region and 50% live in urban areas. The numbers of hazard events within a distance range of 0–40 km from the shoreline are: flooding (non-tidal)—335; tidal flooding—65; and droughts—28. Based on this study, about half of flood disasters (non-tidal) occurred within 10 km of the shoreline, while tidal flooding accounted for 80%. Most of the climate-related disasters were found in rural areas at low levels of population growth, while in urban areas the disasters were found to be associated in less than 1% and in more than 3% of population growth.

Considering the importance of connecting urbanization phenomena and vulnerability assessments, this paper aims to explore vulnerability assessment in three different city sizes in the northern coast of Central Java province of Indonesia. It compares the vulnerability levels of the three cities based on their sizes (that is, levels of urbanization). It uses the most current secondary data from the lowest administrative levels, called as kelurahan (urban village), for its assessment. There are two indexes used to indicate their vulnerability levels, namely exposure and sensitivity index (ESI) and adaptive capacity index (ACI). By combining the ESI and ACI, the study found that the kelurahans in Tegal (the medium sized city) have similar vulnerability levels. The kelurahans in Semarang (as the big city) have more combination of vulnerability levels—indicating that the city has various sensitivity, exposure, as well as adaptive capacity among its kelurahans. In Lasem (the small sized city), due to limitations imposed by adaptation—mostly because of lack of public services and high dependency on primary economic sectors—all of its kelurahans were found to be vulnerable. The study therefore concluded that the bigger a city is, the more the different areas of that city will have varying levels of vulnerability, leading to a high propensity of vulnerability among its inhabitants. On the other hand, the smaller a city is, the less capacity it will have in reducing its emerging vulnerability challenges