Resilience Scanner

Multi-Radar System for Urban Rainfall Monitoring and Flood Prediction

Solution Overview

A demonstration study was conducted in Toyama City and Fukui City utilizing a multi-radar system composed of three compact X-band dual-polarization radars as part of the B-DASH (Breakthrough by Dynamic Approach in Sewage High Technology) joint research project for rainwater management focused on monitoring heavy rainfalls in urban areas.[1][2] This approach combines urban area rainfall radar technology with short-term rainfall prediction models and real-time runoff analysis technology to enhance flood prediction and response capabilities.[1] The system was designed to provide real-time information on rainfall prediction, water level in sewerage pipes, and inland flood prediction to drainage pump operators, stormwater storage pipe managers, and residents in flood-prone areas.[1]

Technical Components

The technology employs the WR-2100, a compact X-band polarimetric Doppler radar featuring an antenna diameter of 1.2 meters.[5] Furuno Electric Co., Ltd. developed one of the world's smallest and lightest weather radars, measuring just one meter in both diameter and height and weighing only 65 kilograms.[3] The research team working with Furuno built a rainfall monitoring system where the weather radar filled a space of just one cubic meter and weighed only 130 kilograms, with an observation range of 50 kilometers.[4] Each radar completes a volume scan consisting of 11 elevation angles (0.5° to 20°) in 2.5 minutes, providing high-resolution rainfall data with a spatial resolution of 250 meters and a temporal resolution of 2.5 minutes.[5] The radar stations collect information on and analyze conditions within 50 meters of the station in each direction, assembling detailed pictures of weather in small areas.[6] Using the radar device, the team could estimate the number of ice particles in the atmosphere to predict rainfall 10 to 20 minutes in advance, as ice particles above 4,000 meters act as the seeds for rain.[4] The radars are installed on building rooftops, with altitudes ranging from 40 meters to 100 meters above sea level, and baseline distances between radars of approximately 20-30 kilometers.[5] The system integrates a rainfall prediction model developed by Kobe University, a flood prediction analysis system from EMORI & CO., LTD., and simulation models for sewage pipelines created by New Nippon Consultants Co., Ltd. and Nihon Suido Consultants Co., Ltd.[2]

Implementation Details

The research group started proof-of-concept tests in May in Fukui City and Toyama City on the Sea of Japan, with three radar stations set up in both cities.[6] METAWATER Co., Ltd. provided multidisciplinary engineering and integration, while FURUNO ELECTRIC CO., LTD. supplied the multi-radar system for urban areas as part of the B-DASH joint research team.[2] Tablet computers were distributed to 16 households—eight in each city—designed to send information on rainfall and areas in danger of flooding when a sudden downpour appeared likely.[6] The total coverage area of the network is approximately 60 kilometers by 60 kilometers.[5] During the study period of about two years, the accuracy of radar rainfall observation was confirmed to be comparable to that of the X-band dual-polarization Doppler weather radar managed by the Ministry of Land, Infrastructure, Transport and Tourism.[1] The research team designed the radars to be compact enough for transportation by car, enabling quick setup in areas where they are most needed at the time.[6] Furuno successfully commercialized its first compact weather radar in 2013, and some 150 units have been installed in 33 countries.[3]

Benefits and Impacts

The comparison with the Japan Meteorological Agency C-band radar showed that the X-band network provides higher and more realistic rainfall rates, especially in heavy rain.[5] The system is expected to allow warnings to be sent out to residents about 10 minutes faster than current technology in use with local governments across Japan, allowing the elderly and others vulnerable to disasters to evacuate vital minutes earlier than is now possible.[6] The demonstration confirmed the effectiveness of flood damage reduction by providing real-time information to operators and residents.[1] Residents themselves could secure lead time for setting up water-stop sandbags and moving their vehicles to higher ground.[1] The comparison with dense rain gauge networks showed good correlation, although there was a slight underestimation by the radar.[5] Internationally, similar implementations in Singapore combine rainfall observations from compact weather radar systems with sewage runoff models to predict and manage the risk of urban flooding.[3]

Climate Adaptation Relevance

This technology addresses extreme precipitation events and urban flooding risks through enhanced monitoring and early warning capabilities. The system's ability to predict rainfall 10 to 20 minutes in advance and provide detailed spatial coverage enables more effective response to sudden downpours and heavy rainfall events that are intensifying with climate change.[4][6]

Business Analysis

The compact weather radar technology was developed by FURUNO ELECTRIC CO., LTD. in collaboration with Colorado State University and the National Institute of Information and Communications Technology, Japan.[5] The first radar network consisting of four such radars has been deployed in the Fukuoka metropolitan area in Japan, demonstrating the technology's scalability beyond the Toyama and Fukui demonstration sites.[5] The system's easy transportation, simple installation, and affordable price have driven adoption by local governments and research institutions, with 150 units now installed across 33 countries since commercialization in 2013.[3] The B-DASH joint research project structure brought together multiple specialized partners including engineering firms, consultants, universities, and technology manufacturers to share development costs and technical expertise.[2] The compact design and lower cost compared to traditional weather radar systems reduce capital expenditure barriers for municipal governments seeking to enhance flood prediction capabilities.[3]

Sources