Southeast Asia, characterized by its tropical rainforest climate, frequent monsoon activities, and mountainous terrain, is one of the regions most prone to mountain flood disasters globally. Traditional single-point rainfall monitoring is no longer sufficient for modern early warning needs. Therefore, it is crucial to establish an integrated monitoring and warning system that combines space-, sky-, and ground-based technologies. The core of such a system includes: hydrological radar sensors (for macroscopic rainfall monitoring), rain gauges (for precise ground-level calibration), and displacement sensors (for monitoring on-site geological conditions).
The following comprehensive application case illustrates how these three types of sensors work together.
I. Application Case: Early Warning Project for Mountain Floods and Landslides in a Watershed of Java Island, Indonesia
1. Project Background:
Mountainous villages in central Java Island are consistently affected by monsoon-heavy rainfall, leading to frequent mountain floods and accompanying landslides, which severely threaten residents’ lives, property, and infrastructure. The local government, in collaboration with international organizations, implemented a comprehensive monitoring and warning project in a typical small watershed of the region.
2. Sensor Configuration and Roles:
- “Sky Eye” — Hydrological Radar Sensors (Spatial Monitoring)
- Role: Macroscopic trend forecasting and watershed areal rainfall estimation.
- Deployment: A network of small X-band or C-band hydrological radars was deployed at high points around the watershed. These radars scan the atmosphere over the entire watershed with high spatiotemporal resolution (e.g., every 5 minutes, 500m × 500m grid), estimating rainfall intensity, movement direction, and speed.
- Application:
- The radar detects a intense rainfall cloud moving toward the upstream watershed and calculates that it will cover the entire watershed within 60 minutes, with an estimated areal average rainfall intensity exceeding 40 mm/h. The system automatically issues a Level 1 warning (Advisory), notifying ground monitoring stations and management personnel to prepare for data verification and emergency response.
- The radar data provides a rainfall distribution map of the entire watershed, accurately identifying “hotspot” areas with the heaviest rainfall, which serves as critical input for subsequent precise warnings.
- “Ground Reference” — Rain Gauges (Point-Specific Accurate Monitoring)
- Role: Ground-truth data collection and radar data calibration.
- Deployment: Dozens of tipping-bucket rain gauges were distributed across the watershed, particularly upstream of villages, at different elevations, and in radar-identified “hotspot” areas. These sensors record actual ground-level rainfall with high precision (e.g., 0.2 mm/tip).
- Application:
- When the hydrological radar issues a warning, the system immediately retrieves real-time data from the rain gauges. If multiple rain gauges confirm that the cumulative rainfall over the past hour has exceeded 50 mm (a preset threshold), the system escalates the alert to Level 2 (Warning).
- Rain gauge data is continuously transmitted to the central system for comparison and calibration with radar estimates, continuously improving the accuracy of radar rainfall inversion and reducing false alarms and missed detections. It serves as the “ground truth” for validating radar warnings.
- “Pulse of the Earth” — Displacement Sensors (Geological Response Monitoring)
- Role: Monitoring the slope’s actual response to rainfall and directly warning of landslides.
- Deployment: A series of displacement sensors were installed on high-risk landslide bodies identified through geological surveys within the watershed, including:
- Borehole Inclinometers: Installed in drill holes to monitor tiny displacements of deep subsurface rock and soil.
- Crack Meters/Wire Extensometers: Installed across surface cracks to monitor changes in crack width.
- GNSS (Global Navigation Satellite System) Monitoring Stations: Monitor millimeter-level surface displacements.
- Application:
- During heavy rainfall, rain gauges confirm high rainfall intensity. At this stage, displacement sensors provide the most critical information—slope stability.
- The system detects a sudden acceleration in displacement rates from a deep inclinometer on a high-risk slope, accompanied by continuous widening readings from surface crack meters. This indicates that rainwater has infiltrated the slope, a slip surface is forming, and a landslide is imminent.
- Based on this real-time displacement data, the system bypasses rainfall-based warnings and directly issues a highest-level Level 3 alert (Emergency Alert), notifying residents in the danger zone via broadcasts, SMS, and sirens to evacuate immediately.
II. Collaborative Workflow of the Sensors
- Early Warning Phase (Pre-Rainfall to Initial Rainfall): Hydrological radar detects intense rainfall clouds upstream first, providing early warning.
- Confirmation and Escalation Phase (During Rainfall): Rain gauges confirm that ground-level rainfall exceeds thresholds, specifying and localizing the warning level.
- Critical Action Phase (Pre-Disaster): Displacement sensors detect direct signals of slope instability, triggering the highest-level imminent disaster alert, buying critical “last few minutes” for evacuation.
- Calibration and Learning (Throughout the Process): Rain gauge data continuously calibrates the radar, while all sensor data is recorded to optimize future warning models and thresholds.
III. Summary and Challenges
This multi-sensor integrated approach provides robust technical support for addressing mountain floods and landslides in Southeast Asia.
- Hydrological radar addresses the question, “Where will heavy rain occur?” providing lead time.
- Rain gauges address the question, “How much rain actually fell?” providing precise quantitative data.
- Displacement sensors address the question, “Is the ground about to slide?” providing direct evidence of impending disaster.
Challenges include:
- High Costs: The deployment and maintenance of radar and dense sensor networks are expensive.
- Maintenance Difficulties: In remote, humid, and mountainous areas, ensuring power supply (often relying on solar energy), data transmission (often using radio frequency or satellite), and physical maintenance of equipment is a significant challenge.
- Technical Integration: Powerful data platforms and algorithms are required to integrate multi-source data and enable automated, rapid decision-making.
- Complete set of servers and software wireless module, supports RS485 GPRS /4g/WIFI/LORA/LORAWANplease contact Honde Technology Co., LTD.
Email: info@hondetech.com
Company website: www.hondetechco.com
Tel: +86-15210548582
Post time: Sep-19-2025