Flooding is among the major catastrophes which occur in all places of the world and results in a massive quantity of damage in the environment. Problem occurs during a flash flood where the citizens may not have time to move their important things from flood area to the safe area. As such there is a need to develop technology for monitoring and alerting the population about flooding. This project presents a flood monitoring system to collect, receive, and analyse data from two different locations situated in Kigali, Rwanda namely the Mpazi brook and Rwampara brook that contribute to the Nyabugogo flood. The data captured by sensors are published using MQTT (Message Querry Telemetry Transport) Protocol to ThingSpeak. Each location has a flood detector system composed of an ultrasonic sensor for measuring the changes of the water level of the brook, rain drop sensor to measure rain intensity, and NodeMCU to collect data from sensors. The water level is used as flood indicator and it can be known remotely. The data collected by these sensors are transferred to ThingSpeak web-based application and send an alerting message to public authorities based on a determined threshold value. The developed flood monitoring system can help public authorities to be informed about the rise of water level and to know whether there is a manifestation of a flood.