Development of a Portable LoRa-Based Data Logger System for Enhanced Flash Flood Monitoring in Remote Upstream Catchments of Sarawak

Abstract

In Sarawak, flash floods are often triggered by intense rainfall over hilly and upland catchments, causing rapid runoff into major rivers and their tributaries. These events pose significant risks to downstream towns, particularly when they coincide with high tides. Although Automatic Weather Stations (AWS) provide essential environmental data for the National Flood Forecasting and Warning System (PRAB), their fixed locations result in limited coverage in remote tributaries. This creates spatial data gaps that reduce the accuracy of flood prediction and early warning. This project aimed to develop a low-cost, portable data logger system to complement existing AWS infrastructure by enabling real-time monitoring in remote upstream areas. The proposed system is equipped with a LoRa communication shield and a Micro-SD card to allow efficient data transmission and storage while operating independently of internet access and the power grid. It also includes locally processed alerts, enabling immediate early warning in the surrounding area, with the same data forwarded to the nearest AWS or server for further dissemination via PRAB. Sensor modules were calibrated to maintain accuracy within a 1% error margin. The system was validated through flood simulation tests and performance evaluation of the LoRa 915 MHz communication module, which demonstrated a strong linear correlation between transmission distance and received signal strength (RSSI). Preliminary analysis using SRTM-derived Digital Elevation Model (DEM) data and hydrological tools in QGIS supported strategic data logger placement. Long Banga was selected as a representative site due to its location in a flash flood-prone sub-catchment with limited AWS coverage. Overall, the proposed system enhances localised flood detection, supports PRAB data requirements and cost-effective solution for strengthening early warning capabilities in remote river basins.