<![CDATA[The Sidoarjo mudflow disaster, which began in 2006, has raised concerns about the stability of the surrounding embankments, making deformation monitoring essential for preventing potential failures. This study develops a low-cost GNSS-based system integrated with NTRIP for real-time deformation monitoring of the Sidoarjo mudflow embankment. The system uses U-blox F9P GNSS modules for both the base and rover stations, transmitting real-time position corrections to ensure accurate measurement of ground movement. Data from the GNSS receivers are uploaded to Dropbox and synchronized with Firebase for real-time visualization via the SHIFT PPLS website. Deformation velocity was analyzed using linear regression, RMSE, and statistical tests, comparing low-cost GNSS measurements with geodetic GNSS measurements. Results show that the low-cost GNSS system achieved horizontal deformation velocities ranging from -2.67 to 2.93 cm/month and vertical velocities from -4.97 to 32.20 cm/month at different observation points. The analysis revealed that the low-cost GNSS system provides accuracy comparable to geodetic GNSS systems, with an RMSE of 0.005 to 0.111 meters. The proximity of the local base station significantly improved the precision and consistency of the measurements. This study highlights the potential of low-cost GNSS technology as an effective, cost-efficient alternative for long-term and sustainable deformation monitoring, which is essential for disaster management in geohazard-prone regions.]]>
