127 / 2024-02-18 11:42:56

Development of a rainfall-rainwater monitoring system for urban flood management

Urban flood, X-band radar, monitoring, sewer, river

Due to the increasing occurrence of extreme weather events and heavy rainstorms, the world is experiencing a rise in flood disasters. In particular, disasters in urban areas result in severe damage to human lives, properties, infrastructure, and social activities. Effective management of urban floods requires an early understanding of flood risk, enabling timely actions. This study introduces a monitoring system composed of real-time rainfall observation and flow monitoring in urban sewers and rivers. The former utilizes a network of X-band polarimetric radars, while the latter relies on a series of battery-driven water level gauges.

The study field was located in a highly urbanized area within the Kuma River basin in northern Kochi City on Shikoku Island, Japan. Within this area, a lot of river regulation measures have been implemented along both the Kuma River and its tributaries. The sewer system was designed to a high standard and effectively managed pluvial flooding even during hourly rainfall events of 77mm. Despite this, residents experienced flood disasters many times over the past decades. To comprehend the behavior of rainwater from precipitation to drainage, a rainfall-rainwater monitoring system was established. During the study period, the system detected typical rainfall events and recorded water level changes in both sewer pipes and the receiving rivers within the study field. The results clearly identified distinct drainage mechanisms for the Kuma River and one of its tributaries. Rainwater responses in sewer pipes and rivers differed based on precipitation and human interventions including drainage pump operations. These results offer valuable insights for enhancing the effectiveness of disaster prevention facilities and improving the existing early warning and evacuation planning system.