“InfraRivChange”: A Web-Based Application to Monitor River Migration at Sites of Critical Bridge Infrastructure in the Philippines

Shifting rivers represent a geomorphic hazard at sites of critical bridge infrastructure, particularly in rivers where migration rates are high. Conventional attempts to map and measure shifts in the position of rivers usually requires manual digitization of satellite imagery using Geographic Information Systems (GIS); this type of analysis is time consuming and so can only be applied to a handful of bridge sites, using a small number of satellite images. As part of the CDRI Fellowship, a cloud computing platform Google Earth Engine (GEE) was used to upscale hazard monitoring assessments at large bridges in the Philippines using Earth observation (EO) data. A user-friendly web-application was designed that enables stakeholders to monitor the relative risk of river migration by analysing thousands of satellite images. The “InfraRivChange” web-application uses freely available satellite imagery from Landsat (30 m spatial resolution) and Sentinel (10 m spatial resolution). The workflow is demonstrated and results from the Gamu Bridge on River Cagayan (Landsat imagery), Itawes Bridge on River Chico (Landsat imagery) and Don Mariano Marcos Bridge on River Lagben (Sentinel imagery) are shown. Outputs can be used by key decision-makers (e.g., the Department of Public Works and Highways) to assess the relative risk of river migration at sites of critical bridge infrastructure. It is recommended to use the “InfraRivChange” web-application as a lowcost remote sensing approach to monitor shifting rivers at sites of critical bridge infrastructure. It is envisioned that the web-application can be applied to other critical infrastructure adjacent to rivers (e.g. road, rail and pipelines) and extended elsewhere to other dynamic riverine settings.