<![CDATA[Navigation safety in inland waterway and ferry transportation is strongly influenced by environmental conditions, particularly fluctuations in river water levels. Real-time water-level information is essential for supporting decision-making in determining safe, comfortable, and efficient navigation routes while optimizing fuel consumption and maintaining schedule reliability. This study aims to evaluate the performance of the JSN-SR04T ultrasonic sensor integrated into an Internet of Things (IoT)-based water-level monitoring system to support navigation safety. The proposed system employs an ESP32 microcontroller as the central data-processing unit and wireless communication interface through a Wi-Fi network. The JSN-SR04T sensor measures variations in river water levels in real time, while the measurement results are transmitted and displayed on a mobile device, enabling users to monitor water-level conditions remotely. The research methodology comprised system design, hardware and software implementation, and sensor performance evaluation. Sensor accuracy was assessed by comparing the ultrasonic sensor measurements with reference measurements obtained manually using a measuring ruler. Ten measurement trials were conducted at different water-level conditions. The results demonstrate that the developed system can continuously monitor water levels in real time with stable performance. The JSN-SR04T sensor achieved an average measurement accuracy of 98.67%, with a measurement error of less than 1.5%. These findings indicate that the proposed IoT-based monitoring system provides reliable real-time water-level information and has strong potential as a decision-support tool for inland navigation safety, route optimization, fuel-efficiency considerations, and mitigation of accident risks associated with changing river conditions.]]>
