REAL-TIME MONITORING OF FLOOD INUNDATION IN URBAN AREA USING LPWA

Abstract

 This paper proposes real-time monitoring of flood inundation in urban area using LPWA (Low Power Wide Area) to prevent or mitigate flood damage. In order to verify that this concept is feasible, we evaluated reliability of radio transmission, reliability of detecting water level, and energy consumption though eight prototype LPWA water detectors driven by dry cells, six settled on river dike and two in drainage around Yokohama Station. The detector transmits a signal when its float type level sensor detects that water exceeds a specified level. As a result, reliability of transmission was 99.94% for 15105 times trying to send signals for 131 days, and fatal voltage reduction of battery was not founded. Water level at river around Yokohama Station correlates closely with tide. Height of four of six devices on river dike were settled between high and low of tide level so as to evaluate reliability of water detection efficiently. Sensitivity of water detection of these devices varied from 76.6% to 86.6% depending on device. A sensor in a drainage was able to detect raised water level by typhoon. However, it also detected raised water level of which cause was unknown. To improve reliability of water detection is therefore seen as a key future priority.