LoRa which is a low power communication module that provides long range low data rate transmission, can be used for sensor nodes placed far apart providing a larger area coverage of flood warning system. An update of NodeMCU ESP8266, the NodeMCU ESP32 is recommended as it is more flexible, more energy efficient and provides extra input output connectivity. NodeMCU ESP8266 is mostly used as it is a combination of microcontroller and Wi-Fi microchip. It is useful to include other sensors for measurement of various hydrological, meteorological and geological data for further use in flood prediction employing artificial intelligence and machine learning methods. Ultrasonic sensor that is largely used for water level detection needs to be waterproof to withstand the environmental elements. The paper further contributes by providing recommendations for the most suitable IoT hardware for a practical, cost effective and reliable flood warning system. The paper contributes by highlighting the sensors, microcontroller and wireless communication, IoT platform and method of installation employed in the literature adopting IoT in flood monitoring and flood warning systems. This paper presents an overview of literature related to the hardware implementation of IoT and the corresponding method of installation in flood warning system.

Various methods of IoT implementation have been used for the purpose of flood monitoring and warning. The advancement of Internet of Things (IoT) technology along with cheap sensors makes IoT based flood warning system an attractive choice for disaster management.

Early warning in flood event can save property and life.

Define areal flood warning