Urban Flood Susceptibility Analysis Using Multi Criteria Decision Analytical Hierarchy Process (AHP) Method: Case Study of Bandung City

Bandung is West Java's largest metropolitan city and Indonesia's third largest. The city of Bandung is very strategic in various aspects, such as accessibility, communication, public facilities, and the economy. The Increased population in Bandung indicates more complex ongoing human activities, which can then affect changes in land use. The land covers in urban areas tends to change more drastically over a short period e than in rural areas because of rapid urbanization. Therefore, urban phenomenon changes are ideally monitored and detected from satellite images with a multitemporal resolution. Vegetation greenness and built-up areas can identify through multitemporal remote sensing imagery. Changes in vegetation and built-up area can monitor using remote sensing with multitemporal imagery. The analysis of changes in vegetation and built-up area studied in Bandung City represents an area with rapid population growth. This study aims to: 1) Identify changes in vegetation greenness in Bandung City between 2014 and 2021, 2) Identify built-up area changes in Bandung City between 2014 and 2021, 3) Analyze the relevance between vegetation greenness and the built-up area in Bandung City—the correlation between NDBI and NDVI through selected samples is representative of all data in Landsat 8 imagery. The proportion between the values of NDBI and NDVI samples is 0.9034. So, it is concluded that the two variables are positively correlated. Therefore, the study’s results recommend preserving vegetated land cover to conserve natural resources and prevent increased land surface temperature.Keywords: Remote Sensing Imagery, Built-Up Area, Vegetation Greenness, Bandung City

Ancient monuments located in urbanized areas are subject to numerous short- and long-term environmental hazards with flooding being among the most critical ones. Flood hazards in the complex urban environment are subject to large spatial and temporal variability and, thus, require location-specific risk assessment and mitigation. We devise a methodological scheme for assessing flood hazard in urban areas, at the monument’s scale, by directly routing rainfall events over a fine-resolution digital terrain model at the region of interest. This is achieved using an open-source 2D hydraulic modelling software under unsteady flow conditions, employing a scheme known as ‘direct rainfall modelling’ or ‘rain-on-grid’. The method allows for the realistic representation of buildings and, thus, is appropriate for detailed storm-induced (pluvial) flood modelling in urbanized regions, within which a major stream is usually not present and conventional hydrological methodologies do not apply. As a case study, we perform a pilot assessment of the flood hazard in the Roman Agora, a major archaeological site of Greece located in the center of Athens. The scheme is incorporated within an intelligent decision-support system for the protection of monumental structures (ARCHYTAS), allowing for a fast and informative assessment of the flood risk within the monument’s region for different scenarios that account for rainfall’s return period and duration as well as uncertainty in antecedent wetness conditions.

Geotechnical, structural and geodetic measurements for conventional tunnelling hazards in urban areas – The case of Niayesh road tunnel project

Long Range (LoRa) technology uses less power consumption. In addition, it supports a more than two-kilometer communication range. However, several challenges need to be overcome, such as the lack of widespread Long Range Wide Area Network (LoRaWAN) in urban areas, especially for reading electricity, water, and gas meters. This research aims to study LoRaWAN's network planning for Smart Metering Infrastructure (SMI) in an urban area in Indonesia, namely Bandung city, by determining the number of gateways required to support SMI device communication using the commercial network simulation software, Forsk Atoll. LoRaWAN uses the unlicensed frequency with a high possibility of interference with similar frequencies. Furthermore, LoRaWAN has limitations in data transmission speeds of 0.3 – 50 kbps and cannot transmit data directly to the server, so it must go through a gateway. Therefore, this research analyzes and simulates the LoRaWAN network coverage and capacity planning gateway in Bandung city. Based on the conducted test, Bandung city is labeled as a city with Spreading Factor (SF) 9, Code Rate (CR) 4, and Relative Signal Strength Index (RSSI) of −129 dBm. The total number of gateways required for Bandung city is five sites. The average acceptable signal level in Bandung city is −92.14 dBm. The average SNR value in Bandung city is −17.49 dB. The average throughput distribution value is 12.1 kbps with a 78% served rate. All of the values obtained have fulfilled the LoRa requirements.

One of the goals in the SDGs that a region must achieve is 100% sanitation access. Sanitation is considered to have a significant impact on the quality of public health, both in rural and urban areas. The city of Bandung as a city with a high-density level has a big challenge in resolving sanitation matters. Acceleration efforts are needed to improve sanitation access in the city of Bandung which is still low so that it can realize open defecation free (ODF) for every urban village in the city of Bandung. This paper aims to provide a logical framework in the form of efforts that can be made to increase ODF in the city of Bandung. By collecting secondary data, interviews and FGDs as well as the highest and best use approach, the results show that the most important thing is to encourage the community to realize the need for a septic tank through community based total sanitation triggering (STBM) activities, connecting household wastewater channels to PDAM Sewerage, construction of small and large-scale communal septic tanks / IPAL and construction of “Gendong” pipelines, especially those in riverbank areas.

Flood hazards in urban areas have decreased markedly in recent years due to the implementation of measures such as dikes, weirs, water gates and other mitigation methods. Consequently, the population of developed or redeveloped urban areas near river basins and coastal areas has increased considerably, and a concomitant increase has been observed in the number of high-rise office buildings and apartments on the alluvium of old urban rivers. While the residents of these structures are sensitive to earthquake damage, they are relatively unaware of the risks associated with flooding. While several flood refuges exist in the vicinity of urban rivers, the intended purpose of these refuges has come to be regarded as that of earthquake emergency measures rather than a measure intended for flooding. Consequently, the placement of many of these emergency refuges does not consider the risk of inundation. In this report, the present condition of such refuge sites in the low lying areas of Tokyo is examined. We also investigated the attitude of residents living in high-rise apartment buildings and detached houses toward flood hazards. Finally, we proposed flood refuge measures that could be implemented to minimize the risk of disaster.

Is local flood hazard assessment in urban areas significantly influenced by the physical complexity of the hydrodynamic inundation model?

Understanding the characteristics of urban airflows with complex geometrical features is very important from viewpoints of assessing strong wind hazards in the region. This study investigated turbulent airflows and strong wind hazards in an urban area by conducting large-eddy simulations (LESs) with explicit representations of buildings and structures. A business district, including historical architectures, of Kyoto City was chosen. The sensitivity experiments with realistic and idealized building arrangements indicated that the actual, complicated arrangement of buildings as well as the building height variability would enhance an unsteady nature of airflows in urban canopy. An analysis of strong wind hazards under a typhoon condition shows that sustained winds are stronger along streamwise-oriented major streets and over open spaces while instantaneous winds become stronger especially within areas with a mixture of high-rise buildings embedded in low-rise building areas/open spaces. It was indicated that wind gustiness increases with the decrease in building plane-area index. The analysis suggested that both the building height variability and the complex arrangement of buildings are considered to enhance the gustiness of surface winds. This study demonstrated that an LES model is practically useful for assessing the strong wind hazards in urban areas.

Nowadays, geo-environmental assessment becomes an immediate concern all over the world. In general, the flow paths of pollutants and radioactive source allocations are related to rock types, subsurface layer distributions and structural settings. Thus, this chapter aims to present a non-conventional integrative approach of remote sensing, structural data and geophysical methods for geo-environmental hazard assessment. Notably, such hazards commonly result from human activities where contaminants are accumulated and spread on or beneath the ground surface. Detection of organic contamination and hydrocarbon flow path is a difficult task for geophysical techniques at hazardous waste areas. Furthermore, radioactive-emission detection is of specific value in the vicinity of mineral resources for human health and environmental preservation. Accordingly, waste management as well as a subsurface contaminant and geological structure mapping are prerequisite for urbanization, mining and civil engineering. In this chapter, we presented cases for waste management to indicate how recent technologies can be used for detection and prediction of geo-environmental hazards in urban areas and desert lands. The following techniques are used to achieve the objective of the chapter: (1) remote sensing, (2) information on structural geology, (3) direct current (DC) resistivity method and (4) airborne geophysics. Regarding four case studies, the results indicate the effectiveness of the suggested approach to map surface and subsurface geological conditions concerning the pollutants and radioactive emissions in 2D/3D. Even when the contaminant itself produces no detectable direct geophysical signature, sometimes it may be found by indirect means through the structural mapping as a guide to predict the contaminant flow paths. Accordingly, the approach will be helpful to the decision-makers to achieve sustainable development in urban and desert areas regarding the waste management aspects. Moreover, the present nondestructive approach can be considered as an initial step in waste assessment projects.

Remote sensing can be used to examine the city of Bandung with variations in its topographical appearance. Apart from that, urban areas such as Bandung generally experience land cover transformation (vegetation and non-vegetation) as well as changes in land surface temperature. This research aims to: 1) Analyse vegetation greenness in the Bandung City, 2) Analyse land surface temperature in the Bandung City, and 3) Analyse the correlation between vegetation greenness changes with dynamics of land surface temperature in the Bandung City. The method used is information extraction through remote sensing imagery to obtain changes of vegetation greenness and dynamics of land surface temperature, as well as field measurements. This research use Landsat 5 and Landsat 8 to get a value of built-up index and vegetation greenness. The results of this research are the identification of the spectral character of vegetation greenness, as well as their influence on land surface temperatures in the Bandung Basin. Types of vegetated land use, including rice fields, parks and plantations, have lower temperatures than settlements, roads, empty land and cemeteries. Positive values in the regression results indicate a correlation between the NDVI and LST variables.

In urban areas, flood susceptibility assessment is of special importance because of the high settlement population, properties, and infrastructures. Geospatial information science (GIS) provides a tool for investigating flood susceptibility based on several aspects including economic damages and critical infrastructures in cities. This study aims to provide a tool based on GIS analyses to support decision‐makers in identifying flood hazards in urban areas, in which previous flood data, flood causative factors, and urban infrastructure data are not adequately available. To assess flood susceptibility in the study area, the related spatial high‐resolution data were produced. Then, flood zones were estimated for different recurrence intervals using meteorological data. Finally, susceptibility was assessed in urban areas for different urban infrastructures using GIS modeling. The model was designed based on the assumption that any critical urban infrastructure, such as power towers, was affected by flood zones and, in addition to flooding, could cause hazards by itself. Moreover, five scenarios were defined to calculate susceptibility when in the problematic locations of the floodway. DoAsb Floodway was chosen as a case study located in Zanjan city, northwest of Iran. The results indicated the high‐susceptible areas around the floodway. Moreover, the flood susceptibility level for each urban infrastructure in the study area was calculated and classified into five classes from low susceptible to very high susceptible. Also, the results of the five scenarios showed if some parts of the floodway had problems, the susceptibility rate would be high. The generated flood susceptibility maps of this model can be used to plan suitable programs in order to avoid flood damage and ensure public safety.

Bandung has about 2.5 million people that reside in 9.267 ha urban area. Bandung city has only about 189 hectares of urban park, which is not enough to serve all the settlements area. This study analyzed the level of accessibility of residents to the park services, in term of how far and wide the city park can serve the surrounding community. This research used Network Analysis in Geographic Information System (GIS) method to calculate the Services Area. The method used assumption that one park can be reached by residents walking in radius 1.250 km around their house. The result show that the existing of the park in Bandung City can only serve about 6.942 Ha of urban area, which is only serve 2/3 urban area in Bandung City. City parks in Bandung City have not been distributed well, especially in the eastern and western part of Bandung City, which have blank spot areas in which the residents are unable to reach to a city park. The result of this research can serve as an input to the local government in the planning of building new city parks, which will be beneficial for the residents of eastern and southern area of Bandung City.

North Bandung Area (NBA) was designated as a protected area to regulate the water system around Bandung City. Land conversion from vegetated land into built-up areas can decrease groundwater, increase the risk of floods, landslides, and Land Surface Temperature (LST). This study was conducted to describe LST distribution based on land cover types in specific years of 2010, 2014, and 2018. Landsat 5 and 8 Surface Reflectance (SR) Tier 1 imagery data, West Java land cover maps established by BAPPEDA West Java, and RBI administration maps at a scale of 1: 25,000 were used to generate a map of land cover and LST in this research. There are four land cover classes in NBA, i.e., vegetation, water bodies, open areas, and constructed areas. Within eight years observation (2010 to 2018), bare land decreased from 67.6% (2010) to 57.5% (2018). However, coverage of constructed areas increased within eight years of observation from 22.8% to 27.7 %. In addition, due to the reforestation program, vegetation coverage has slightly increased from 9.6% to 14.7%. LST can be classified into three classes, i.e., low, medium, and high temperature. The area with low and medium-class temperatures decreased from 19% to 16% and 61.3% to 51.7%, respectively. However, high LST increased in NBA 18.7% to 30.3%. The enhancement of 5% vegetation area did not significantly reduce land surface temperature in NBA due to forest conversion to constructed area. Therefore, vegetation coverage must be escalated by reforestation program around NBA to reduce land surface temperature.

Abstract. Land cover change (LCC) is one of the most important global environmental issues in this modern era. Land cover change that occurs at local scales can impact global ecosystems due to cascading effects. The relationship between human population growth, urbanization, and land resource pressures at various spatial and temporal scales has led to these changes. In Bandung City, the increase in population and urbanization over the years has led to a decrease in land resources and a worsening of disasters and climate change. This includes the Cikapundung watershed, where the transformations of green land into built-up areas have caused flooding that affected more than 600 houses in early 2024. This makes it even more important to not only understand historical and current land cover change patterns, but also understand the causes of land cover change and predict future spatiotemporal trends for strategic planning of human settlements, land use, and resource conservation in Bandung City. This study aims to identify the causal factors of long-term land cover change over 50 years (1973–2023) in the Cikapundung watershed and its surroundings. Land cover classification was conducted using random forest algorithm based on Landsat 5, Landsat 8, and Sentinel-2 satellite images. The causal factors of LCC were identified to see the change from non-urban to urban using regression analysis. This study is intended to provide insight into the factors influencing LCC in the Cikapundung watershed and its surroundings so that it can be used to develop effective policies to mitigate the significant impacts of land cover change.

Land subsidence is a problem in several big cities and areas in Indonesia; some of them occurred in Jakarta, Bandung, Semarang, and the North Coast of Java location. The subsidence conditions are different and highly dependent on many factors, including geological and excessive groundwater extraction. One of the cities experiencing severe subsidence conditions in Indonesia is Bandung. This research is based on Interferometric SAR analysis using C-Band Sentinel 1A frequency data released by the European Space Agency (ESA), recorded on 11 November 2018 and 18 November 2019. Based on the analysis of SAR interferometry, Bandung City experienced subsidence with an average size of 6 cm per year. The city of Bandung is located between the mountains and can be described as a bowl. The city of Bandung itself is formed from alluvial plains resulting from the sedimentation process from the surrounding mountains. Geologically, the city of Bandung can be described as a city composed of materials that have not undergone a perfect consolidation process. This condition causes the city of Bandung to be prone to land subsidence disasters. In addition, another factor that plays a dominant role in the process of excessive groundwater extraction by residential and primarily industrial activities scattered in the Bandung area. If not handled properly, the phenomenon of land subsidence in the city of Bandung will cause a very detrimental impact, reduce the carrying capacity of the environment, and threaten the sustainability of the city. Among the actual effects on the broader area in Bandung that is affected by floods, especially during the rainy season.