Flooding is one of the major problems in Indonesia that negatively
affects the environment and people's lives. Overflowing water in rivers
and sewers is the main cause of this disaster. Limited information on
water levels and the difficulty of reporting the condition of the
surrounding environment make it difficult for people to take mitigation
actions. This research aims to develop a website-based water level
monitoring system that can display real-time data to support flood
mitigation. The system was developed using waterfall methodology and
integrates the HC-SR04 sensor and ESP-32 microcontroller with the
WebSocket protocol to send real-time water level data to the website.
The data obtained is visualized in the form of an interactive map with a
water icon consisting of 3 colors according to its height status, namely:
blue (safe), yellow (alert), and red (danger). The system has a reporting
feature for residents and gallery photos of flood management activities.
Testing results show that the sensor has an average error value of
1.09%, which indicates that the sensor is reliable for measuring water
level. Furthermore, usability testing using the System Usability Scale
(SUS) method yielded a high score of 86.53, indicating that the system
is highly acceptable and user-friendly.