The most hazardous type of floods are flash floods, which combine the devastating force of a flood with extremely high speeds. This project entails creating a flash flood warning system that can identify floods and instantly notify drivers plying Nkpolu Road in Rumuigbo, Port Harcourt, using a mobile device. Soil samples collected from Nkpolu Road were transferred to the laboratory and examined, along with rainfall data collected from the Nigeria Meteorological Agency (NIMET). On the basis of the examination of the soil samples and rainfall data, the measurement apparatus was constructed. The HC-SR04 ultrasonic sensor, the SIM900L data transmission module, the DFRobot gravity pH sensor, the SHT20 soil temperature/humidity sensor, and the Arduino microcontroller are all integrated into the system. According to the analysis, the soil types on Nkpolu Road are sandy loam and loamy sand, and the intensity of the rainfall is often highest between July and September.The system on Nkpolu Road was designed to send out warning messages via a mobile device every six minutes and to identify flash floods when it rained. When the rain started to come down, the alerts would progress from saying "no flooding" to "minor flooding," "moderate flooding," and eventually "severe flooding." They would then send out warnings in real time as soon as each degree of flooding was determined. The warning that day that it rained was "no flooding". When it didn't rain at all, no warning signal was sent. When the Nkpolu Road floods, this technology helps drivers avoid the area and instantly switch to another route that is open.