An open-source and low-cost data acquisition system for surface water monitoring: analysis of measurement uncertainty

River water level monitoring is the process of monitoring water in rivers that sometimes overflow and cause flooding. Residents need to know the water level to serve as an early warning. Therefore, it is necessary to have a measurement mechanism and river water level information in order to provide information to the community. Monitoring river water levels in this research uses the HC-SR04 ultrasonic distance sensor and water level sensor. Arduino Uno is used as a microcontroller. This research uses a prototype with water level measurements observed at 3 cm (low), 3-5 cm (medium), and 5 cm (high). The water level can be monitored from anywhere through Blynk. The implementation of the resulting water level has been successful in accordance with the parameter values on the water level sensor which is marked by the display of numbers on the LED, the color of the lights, and different alarm sounds for each water level. HC-SR04 ultrasonic sensor is able to measure and provide water level data in realtime and from any place using Blynk.

In common mini hydro power plants in Indonesia, the control of water levels in intake, sand-trap and head pond is carried out manually. This conventional manual control system may cause damages of waterway and all its components due to overflow or transient flow of water during load shedding or black out of electricity grid. The damages eventually may increase cost of maintenance and increase the risk of waterway collapse or excessive water hammer in penstock pipe. This type of collapses often happen in many mini hydro power plants in Indonesia. The risk of damages can be reduced by installing water level control and monitoring system in all key water way components such as in intake, sand-trap and head pond. Some other mini hydro power plants have installed water level control and monitoring system. But the price of such control system is still very expensive and high operation and maintenance cost. Thus, this thesis work designs and simulates simple and inexpensive the water level control and monitoring system for a mini hydro power plant. In this thesis work, the design and simulation of the water level control and monitoring system are carried out by a simulated three water tanks where the water levels in the tanks are monitored and controlled by using ultrasonic level sensors and motorized valves respectively. A simple and inexpensive Arduino based water level control and monitoring system is successfully designed to fulfil the requirement of quick or fast respond for water level control in the simulated model.

- This project focuses on the design and development of an Automatic Dam Gate Control System that prevents floods and maintains safe water levels in dams during the rainy season. In conventional systems, dam gates are operated manually, causing delayed responses and increasing the risk of water overflow that can severely impact nearby farms, industries, and urban areas. The proposed system introduces automation through the integration of water level sensors, a microcontroller, and a motor-driven chain mechanism. When the water level exceeds a predefined threshold, the sensors transmit a signal to the controller, which activates the motor to automatically open the dam gate. Once the water level returns to a safe range, the gate is closed automatically. The entire system is powered by solar energy, supported by an energy storage device (battery unit) that stores electricity generated by the solar panel to ensure continuous operation even during cloudy weather or nighttime. This sustainable and intelligent system enables real-time water level monitoring, minimizes human intervention, and enhances the efficiency and safety of dam operations, contributing to effective and eco-friendly water resource management. Key Words: Automatic Dam Gate Control, Water Level Monitoring, Microcontroller-Based Automation, Solar-Powered System Flood Prevention Technology, Motor-driven gate mechanism,

Aims: With the stick, blind people can not only project their goals well, but also anticipate obstacles from the front, right, left, and unexpected puddles below without physical contact.
 Study Design: Obstacle Detection Stick for the Visually Impaired Using HC-SR04 Ultrasonic Sensor and Arduino Nano Microcontroller-Based Raindrop Sensor.
 Methodology: Calibration is performed by comparing the output value of the HC-SR04 ultrasonic sensor and the manual meter. The calibrated parameters are the distance of the obstacle at the front, left and right positions. The relationship between the measured values of the design tool and the manual measuring instrument is determined by the linear regression method to obtain the correction equation and the accuracy of the design tool.
 Results: Based on the research, the working system of the tool for the blind using an ultrasonic sensor is that when the obstacle is in the left position, the tool will emit a right turn sound and vice versa, when the obstacle is in the front and left position of the sensor, the tool will emit a right turn sound and when the obstacle is in the front and left position of the sensor, the tool will emit a left turn sound, If the obstacle is in the front, left and right positions, the tool will emit a U-turn sound and if the obstacle is in the front position, the tool will emit a U-turn sound, the sound produced comes from the audio card's SD module where the sound was previously recorded and the media used as the obstacle is the card. The percentage level of accuracy obtained by the HC-SR04 ultrasonic sensor in the front position is 96.875%, in the left position is 90.625%, and in the right position is 93.75%. The maximum distance the ultrasonic sensor can detect is 147 cm. In the raindrop sensor, the buzzer sounds when the raindrop sensor detects water if the raindrop sensor reading is more than 5 cm from the bottom of the blind cane, and the buzzer does not sound if the raindrop sensor reading is less than 5 cm.
 Conclusion: The HC-SR04 ultrasonic sensor works by using the obstacle's ability to reflect back the ultrasonic waves sent by the ultrasonic sensor to detect the distance between the stick and the obstacle.

Research on installation and evaluation of early warning systems based on the HC-SR04 ultrasonic sensor and the Internet of Things (IoT) has been successfully carried out. This study aimed to install and evaluate a flood early warning system based on the ultrasonic sensor HC-SR04 and IoT at a flood monitoring post, Boyong River Yogyakarta. Installation of a flood early warning system based on the HC-SR04 and IoT ultrasonic sensor was carried out by preparing tools and materials, connecting WiFi, and installing the system. Evaluation accuracy of the system was carried out by varying the distance between the sensor and the water surface, namely 5 cm - 200 cm with 5 cm intervals, while testing of precision and success were done by 10 times repeating for each distance variation. The results showed that flood early warning system based on ultrasonic sensor HC-SR04 and IoT has been successfully installed at the flood monitoring post, Boyong River Yogyakarta. In addition, the flood early warning system based on ultrasonic sensor HC-SR04 and IoT was successfully evaluated with an accuracy value 99.95%, repeatability precision 98.75%, reproducibility 99.27%, and success 89.50%.

Blind stick or white cane is introduced to blind people after the First World War as a mobility tool to detect the obstacles in the path of the user. This paper proposes an Arduino Nano based obstacle finding stick for visually-impaired people, which helps a blind person by detecting the obstacles using Ultrasonic sensors and android mobile application. It is able to inform the blind person about the circumstances & present condition of the path where he/she is walking. The main objective of this paper is to help a blind people to move more freely by using a reliable stick. The device consists of arduino nano, HC SR-04 ultrasonic sensor, HC-05 Bluetooth module, push buttons, 100nF ceramic capacitors and a 9V battery as the power source. And the android app is developed using MIT App Inventor 2.

Detection of water surface altitude is an indicator for early detection of flood disasters. The research aims to design a water surface-level detection system by using ultrasonic sensors and the ESP8266-12E module. The tools and materials used during the design are: Ultrasonic sensors HC-SR04, module ESP8266-12E, and buzzer a water container with a varied water height, the detection data will be sent to the ESP8266-12E module, then the system will send the information an output to sound the alarm. The ultrasonic HC-SR04 sensor will detect the mation in the form of a message through telegram and buzzer application. The messages delivered are several stages including standby, alert, and danger. The methods used in this design are planning, study libraries, collection of tools and materials, hardware plan, and program creation on the software. The final result is a system capable of detecting water surface level based on the ultrasonic sensor HC-SR04 and the ESP8266-12E module through telegram and buzzer communication media.

It has been designed the water surface level detection system based on the ultrasonic sensor HC-SR04 and the ESP8266-12E module through telegram and buzzer communication media.. The research aims to design a water surface-level detection system by using ultrasonic sensors and the ESP8266- 12E module. The tools and materials used during the design are: Ultrasonic sensors HC-SR04, module ESP8266-12E, and buzzer as an output to sound the alarm. The ultrasonic HC-SR04 sensor will detect the water surface level, the detection data will be sent to the ESP8266-12E module, then the system will send the information in the form of a message through telegram and buzzer application. The messages delivered are several stages including standby, alert, and danger. The methods used in this design are planning, study libraries, collection of tools and materials, hardware plan, and program creation on the software. The final result is a system capable of detecting water surface level based on the ultrasonic sensor HC-SR04 and the ESP8266-12E module through telegram and buzzer communication media. The success rate of this tool system at several stages among others at a standby of 77%, at a level of alert of 70%, and the level of success at the hazard level is 83%.

Inventory management systems are very crucial for businesses to control their stock, keep a track of their stock, and optimize inventory levels to meet users' demand while minimizing costs. In this regard, we have proposed an inventory management system with very low cost by exploiting the properties of the Internet of Things (IoT) and a cloud server. Additionally, we have used an HC-SR04 Ultrasonic Distance Sensor, an Arduino Nano Microcontroller, a white breadboard, and a laptop to design the automatic Inventory management system. The HC-SR04 Ultrasonic Distance Sensor is used to sense and detect objects, connected to the Arduino Nano. When any item is moved from the inventory, the sensor senses and sends a signal to the microcontroller. A Python script is run on the same port continuously as a listener connected to the Arduino Nano. The Python code is invoked, which calls a pickup Application Programming Interface (API). This API is designed using Oracle APEX to update the inventory status of the corresponding item from “In Stock” to “Picked Up” in the cloud database. All backend services, including the database, REST APIs, and monitoring dashboard, are built using Oracle APEX. The dashboard offers real-time inventory insights, enabling users to track items that are picked up, shipped, or in stock. This end-to-end flow enables efficient, automated inventory tracking with minimal manual intervention. Finally, A laptop is used to monitor the inventory status.

Baby weight and length measurement system has been designed based on ultrasonic and load cell sensors with data storage using MySQL database and website interface. This research aims to produce a baby weight and length measurement system with microcontroller NodeMCU ESP32. The system is designed with an ultrasonic sensor HC-SR04 and four half-bridge load cells of 50 kg. The ultrasonic sensor works on the piezoelectric and inverse piezoelectric principles, while load cell sensors work on strain gauge principles. An ultrasonic sensor measures body length, while a load cell sensor measures body weight. According to the Ministry of Health of the Republic of Indonesia’s regulations, this system also has an LCD 20×4 to display measurement and nutritional status assessment results. The experiment used four doll objects with different lengths and weights. This research shows that the ultrasonic sensor HC-SR04 used in this research has an average error of 0.494% in length measurement. The load cell sensor and HX711 ADC used in this research has an average error of 0.949% in weight measurement. The designed system automatically assesses the nutritional status and stores the measurement result and nutritional status in the database to be displayed on the website.

Various electronic travel aids for people having visual impairment have been developed based on ultrasonic object detection employing the HC-SR04 ultrasonic proximity sensor. However, most of them do not consider blind spots where harmful objects cannot be detected. This study discusses the development of a vest that can detect objects in front of the blinds more widely and provide sound alert if an object in front is detected. This detector was developed based on an Arduino Uno equipped with five HC-SR04 ultrasonic sensors, and a mini DFPlayer module. In addition, blind area analysis of sensor detection is carried out to overcome objects that are not detected by similar studies. Horizontally, this travel vest sweeps objects up to 150 cm in distance with a 25o right or left angle deviation from forward direction. Vertically, object detection reaches up to 150 cm in distance with both upward and downward deviation of 30o from the vest.

In the 4.0 era, walking aids for the visually impaired are needed, especially when the user is indoors and outdoors. There are already many tools created, one of which the author wants to make is a wristband. Components include: Ultrasonic Sensor HC-SR04, Arduino Nano, Servo SG90 Motor, and Buzzer. The stages in this study are designing hardware, designing programs, and implementing and testing tools. The testing carried out on this tool is to read the results of objects with distances of 80cm, 90cm, 100cm, 110cm and 120cm. Not only did it test the distance, it also tested the rotation angle performed by the servo motor to drive ultrasonic sensors by 0o,60o,and 120o. It aims to be able to detect in any direction. The results of this tool test have a repeatability rate of 98%, as well as a 97.33% success rate for detecting objects.

Visually impaired individuals face challenges in moving safely, affecting their independence and increasing the risk of accidents. This work presents the development of a prototype accessory for canes with ultrasonic sensors, designed to enhance mobility and independence at a low cost. The device, based on IoT, uses an Arduino Nano, an HC-SR04 ultrasonic sensor, and a buzzer, generating progressive acoustic alerts based on obstacle proximity. During testing, it demonstrated high effectiveness in detecting large objects and issuing immediate alerts; however, it showed limitations with small objects, liquids, and humid environments. The need to optimize the battery, which is currently replaceable, was identified, and as a future improvement, the incorporation of wireless charging technologies and LIDAR sensors was proposed for more precise detection. Additionally, it was recommended to include a night LED to alert others and improve the cane's materials for greater durability. The prototype's design is lightweight, accessible, and functional, prioritizing simplicity without compromising reliability. Compared to similar devices, it stands out for its effectiveness and low cost, offering a viable solution to improve the mobility and independence of visually impaired individuals, reducing risks and facilitating social integration.

Monitoring the water level at smart home system is an effort to increase the comfort and safety of its residents. Therefore, this study aims to design and develop a water level monitoring application that can be implemented to smart home system using the ESP8266 NodeMCU, HC-SR04 ultrasonic sensor, MQTT protocol, and the Flutter framework. By implementing Flutter as an open-source framework for creating applications, it can be monitor water levels in real-time accessed from various platforms: such as Android, iOS, Web, Windows, macOS, and Linux. The test expected to function correctly and provide accurate and real-time information regarding water levels in the surrounding area and can be accessed using various platforms. This research likely to be successful because previous studies conducted the same components in this study.

Flooding can occur due to overflowing water during the rainy season, therefore early detection of the water level in dams as water runoff processing structures is needed. When heavy rain occurs it can result in flood disasters that are detrimental to communities, dam infrastructure and agricultural land. This research aims to monitor water levels online as initial information about impending flood disasters. Monitoring using Internet of Things (IoT) based technology is intended to obtain water level information in real time. In this device the HC-SR04 ultrasonic sensor is used as a water level reader, a waterflow sensor as a water discharge reader and a servo motor as a sluice gate controller. The results of this research are a prototype of a water level detection device that can provide water level information and can control sluice gates. automatically and can be controlled manually or remotely via the latest notifications in the Blynk application using the MQTT protocol. This research was carried out by taking information based on the results of direct observations and interviews with officers at Kambaniru Dam, Lambanapu Village, Kambera District. In this way, the prototype of this detection tool will be easy to use as initial information about the possibility of flooding.