FloodGuard: Smart Flood Detection and Early Warning System Using C++ and Robotic Sensors

🌊 Introduction

Floods are among the most devastating natural disasters, causing massive loss to life, property, and infrastructure. In many flood-prone regions, early detection and alert systems can save lives and minimize damage. In this blogpost, we’ll build a C++-based smart flood detection system using robotic sensors, targeting microcontroller platforms like Arduino or Raspberry Pi.

This project, named FloodGuard, will monitor water levels, send real-time alerts, and act as a preventive measure in rural and urban flood zones. We'll write and explain the entire C++ code, integrate real sensors, and simulate outputs. The blog is designed for developers, students, and educators.

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🚀 Overview of the Project

🎯 Objective:

To create a flood monitoring system that detects rising water levels and alerts users via LED, buzzer, and SMS using a GSM module.

🧠 System Capabilities:

• Monitor water level using ultrasonic/water-level sensor

• Trigger buzzer/LED when dangerous level is reached

• Send SMS alert using GSM module

• Display sensor readings in serial monitor or optional GUI

• Designed using C++ for Arduino/Raspberry Pi boards

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🛠️ Required Hardware Components

Component	Quantity	Description
Arduino UNO/Nano	1	Microcontroller board
Ultrasonic Sensor (HC-SR04)	1	For distance/water level measurement
Buzzer	1	Audible alert
LED (Red/Green)	2	Visual warning indicator
GSM Module (SIM800L)	1	For sending SMS alerts
Resistors (220 ohm)	2	For LEDs
Breadboard + Wires	-	Circuit prototyping
USB Cable	1	Upload code to Arduino

Optional: Raspberry Pi instead of Arduino, LCD display, IoT cloud service (e.g., Blynk)

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⚙️ How It Works

🧪 Principle:

The system uses an ultrasonic sensor to measure the distance between the sensor and the water surface. If the distance decreases below a predefined threshold (indicating rising water level), the system:

• Activates a buzzer and LED

• Sends an SMS warning to a predefined phone number

📊 Threshold Setup:

• Safe: Distance > 15 cm

• Warning: Distance between 7–15 cm

• Danger: Distance < 7 cm

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🧾 Complete C++ Code (Arduino-Based)

#define trigPin 9
#define echoPin 10
#define buzzerPin 6
#define greenLED 5
#define redLED 4

#include <SoftwareSerial.h>
SoftwareSerial gsm(7, 8); // RX, TX for GSM

long duration;
int distance;
bool smsSent = false;

void setup() {
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  pinMode(buzzerPin, OUTPUT);
  pinMode(greenLED, OUTPUT);
  pinMode(redLED, OUTPUT);

  Serial.begin(9600);
  gsm.begin(9600);
  delay(1000);
  Serial.println("FloodGuard system starting...");
  sendSMS("FloodGuard online. Monitoring initiated.");
}

void loop() {
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  duration = pulseIn(echoPin, HIGH);
  distance = duration * 0.034 / 2;

  Serial.print("Water Level: ");
  Serial.print(distance);
  Serial.println(" cm");

  if (distance > 15) {
    digitalWrite(greenLED, HIGH);
    digitalWrite(redLED, LOW);
    digitalWrite(buzzerPin, LOW);
    smsSent = false;
  }
  else if (distance <= 15 && distance >= 7) {
    digitalWrite(greenLED, LOW);
    digitalWrite(redLED, HIGH);
    digitalWrite(buzzerPin, LOW);
    smsSent = false;
  }
  else if (distance < 7 && !smsSent) {
    digitalWrite(buzzerPin, HIGH);
    digitalWrite(greenLED, LOW);
    digitalWrite(redLED, HIGH);
    sendSMS("WARNING: Flood danger! Water level critical.");
    smsSent = true;
  }

  delay(2000);
}

void sendSMS(String message) {
  gsm.println("AT+CMGF=1");
  delay(100);
  gsm.println("AT+CMGS=\"+923001234567\""); // Replace with your number
  delay(100);
  gsm.println(message);
  delay(100);
  gsm.write(26);
  delay(1000);
}

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🖼️ System Diagram

Image: Circuit showing Arduino, HC-SR04, LED, buzzer, and GSM module

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📸 Real-Life Use Case Scenarios

🌧️ Rural Villages:

• Protect crops, homes, and lives during monsoon season

🏙️ Smart Cities:

• Deployed in underpasses, riverbanks, and drainage lines

🏫 Educational Projects:

• STEM students can learn robotics, coding, and sensor interfacing

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🔍 Code Breakdown (Key Concepts)

• pulseIn(): Measures the duration of the ultrasonic echo

• Serial.print(): Debug output to Arduino IDE

• SoftwareSerial: Allows GSM communication

• Digital Output: Controls LED and buzzer based on logic

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🛡️ Enhancements and Ideas

• Add Wi-Fi/Bluetooth module to upload data to the cloud

• Use SFML in desktop simulation for real-time graphs

• Use water quality sensor to detect chemical flood risks

• Integrate solar panel for remote areas

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📗 Conclusion

FloodGuard is a powerful demonstration of using C++ and robotic sensors to combat real-world challenges like flooding. With low-cost sensors, some programming skills, and a microcontroller board, communities can take the first step toward building disaster-resilient infrastructure.

🌟 Stay safe, stay prepared. Build smart solutions with code!

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