QoS in IoT-based River Flood Monitoring System using MQTT Brokers in Tandem Connection

River floods are destructive and occurring frequent everywhere in the world. Especially the developing countries in Southeast Asia are constantly exposed to the risk of river flooding during typhoons and cyclones. River floods can be detected early in advance by monitoring water levels in real-time. In this paper, we propose an architecture using MQTT brokers in tandem connection for low-cost IoT-based river flood monitoring system. For adoption of this architecture, QoS levels in MQTT are evaluated and QoS1 is concluded as the best practical selection.