Seoul has been increasingly exposed to the risk of urban flooding due to the effects of climate change, including frequent localized heavy rainfall events. The unprecedented flooding in August 2022 revealed critical limitations in the city's disaster response and flood forecasting systems. This incident underscored the urgent need for a more robust, real-time hydrological observation network capable of supporting rapid urban flood warnings and disaster management efforts. In response to these challenges, Seoul established the nation’s first urban flood warning system in 2023. This system integrates rain gauges and road surface water level sensors distributed across the city, with warnings issued based on specific rainfall and inundation thresholds. Currently, Seoul operates approximately 1,461 hydrological monitoring devices, including rain gauges, river level meters, sewer conduit level sensors, and CCTV cameras. The city also collaborates with national agencies to enhance the efficiency of hydrological information sharing. However, several issues have been identified within the current system. Many observation devices are improperly located without sufficient consideration for terrain or drainage characteristics, resulting in limited effectiveness. Measurement standards and data collection frequencies vary widely, and redundant installations cause administrative inefficiencies and unnecessary maintenance costs. Furthermore, overlaps between local and national observation networks exacerbate operational inefficiency, while some critical areas remain uncovered, creating blind spots in monitoring capabilities.
The main purpose of this study is to diagnose the current conditions of Seoul's hydrological observation system and propose an optimized operational strategy to improve data quality, reduce maintenance costs, and strengthen flood response capacities. The study sets out to correct inefficiencies, remove redundancies, propose strategic new installations in high-risk areas, and suggest policy directions for sustainable management of the monitoring network. Special attention is given not only to increasing the quantity of devices but to enhancing the overall quality and usability of hydrological data. The scope of the study focuses on observation devices critical for real-time flood monitoring and urban water management, including rain gauges, river water level sensors, flow meters, sewer level monitors, and road surface water sensors. Devices for long-term water cycle monitoring, such as evaporation and groundwater sensors, were excluded from the scope, as were specialized instruments installed inside flood control facilities. Using GIS-based spatial analysis, field investigations, and flood history data, the study evaluates the existing observation network’s coverage, redundancy, and blind spots. This includes consolidating overlapping sites, relocating certain devices, and installing new sensors in critical areas previously left unmonitored. Additionally, the study emphasizes the need to align future hydrological network expansion with Seoul’s broader smart city and digital infrastructure initiatives. Leveraging technologies such as IoT-based low-power communication networks, AI-based flood detection systems, and smart CCTV monitoring is proposed to enhance real-time situational awareness and operational efficiency. Moreover, continuous quality control measures, including regular calibration and maintenance protocols, are recommended to ensure the long-term reliability of collected data.
Through these improvements, Seoul aims to develop a resilient, future-ready urban hydrological observation system capable of effectively mitigating flood risks, enhancing disaster preparedness, and supporting sustainable water resource management in an era of climate uncertainty.