<![CDATA[Information about the arrival of floods in rivers must be informed immediately to the community so that it can save people along the river and its surroundings from the dangers of flooding which are very detrimental. Several cases of flooding have resulted in huge losses in the form of loss and damage to property. Nearly 2000 people were affected by the flood. Early warning and monitoring of floods in rivers with the ESP8266 Microcontroller and Arduino nano is the right solution to overcome this problem. With the Research and Development and Experiment research methods. The working system of the tool based on the water level sensor installed in the upstream area of the river will be received and processed by the Arduino Nano, the sensor data is communicated to the ESP8266 device (as a wifi node). Furthermore, the ESP8266 will send information to the Android application and display it in the form of lights and alarm Buzzer. In the process of testing the tool, Water level status, LED lights, alarm Buzzer and telegram notifications, the tool can work well and is able to provide appropriate information. This system is very cost effective and low power consumption. Flood information will be sent to the community along the river that flows in the city and residential areas, so that people can immediately prepare and save themselves and their property. This can minimize the impact of flooding on the community.Keywords: Arduino Nano; ESP8266; Flood Monitoring; Early Warning AbstrakInformasi datangnya banjir di sungai harus di informasikan secepatnya pada masyarakat sehingga dapat menyelamatkan masyarakat di sepanjang aliran sungai dan sekitarnya dari bahaya banjir yang sangat merugikan. Beberapa kasus banjir telah mengakibatkan kerugian yang sangat besar berupa kehilangan dan kerusakan harta benda. Hampir 2000 jiwa terdampak banjir tersebut. Peringatan dini dan monitoring banjir di sungai dengan Microcontroller ESP8266 dan Arduino nano adalah solusi tyang tepat untuk mengatasi masalah tersebut. Dengan metode penelitian Reseach And Developmen serta Eksperimen. Sistem kerja alat berdasarkan sensor ketinggian air yang dipasang di daerah hulu sungai akan diterima dan diproses oleh Arduino Nano, data sensor dikomunikasikan ke perangkat ESP8266 (sebagai node wifi). Selanjutnya ESP8266 akan mengirimkan informasi ke aplikasi andoid dan menampilkan dalam bentuk nyala lampu dan Buzzer alarm. Pada proses pengujian alat, Status ketinggian air, lampu LED, Buzzer alarm dan notifikasi telegram, alat dapat bekerja dengan baik dan mampu memberikan informasi yang sesuai. Sistem ini sangat hemat biaya dan konsumsi daya yang rendah. Informasi banjir akan di kirimkan pada masyarakat di sepanjang sungai yang mengalir dalam kota dan pemukiman warga, Sehingga masyarakat dapat segera bersiap-siap dan menyelamatkan diri serta harta benda mereka. Hal tersebut dapat meminimalisir dampak banjir pada Masyarakat. ]]>
