Minimum Burial Depth for River-Crossing Pipelines under Clear-Water Flow Conditions

Canada possesses the third largest oil and gas pipeline network globally, with nearly 30% dedicated to crude oil transport. While pipelines offer an efficient means of transportation, those crossing rivers are especially vulnerable to riverbed scour. During high flow events, erosion of the soil surrounding buried pipelines can lead to unsupported spans and increased risk of vortex-induced vibrations (VIV), potentially causing structural fatigue and failure. This research aims to determine the minimum burial depth required to prevent scour around pipelines subjected to clear-water flow conditions. Addressing a critical gap in sediment transport and erosion protection design, the study holds significant relevance for civil and environmental engineering applications. A series of laboratory flume experiments were conducted, where a cylindrical pipeline was placed at varying embedment depths relative to a uniform sediment bed. Under steady unidirectional flow, the development of local scour around the pipe was monitored over time. High resolution images of the sediment bed were captured at regular intervals and analyzed using a custom MATLAB script. The code detected the sediment-water interface and converted pixel data into real-world coordinates. Elevation profiles were extracted and interpolated to measure scour depth and extent over time. Results showed that pipeline embedment plays a crucial role in resisting scour formation. Pipes fully embedded beneath the sediment experienced minimal to no scour, while shallow or exposed pipes developed significant scour holes that deepened and lengthened with time. These findings support the development of predictive guidelines for minimum burial depth and enhance understanding of the interaction between flow, sediment transport, and pipeline exposure. This study contributes valuable empirical data and a robust image-based analysis method for future research and design practices in river-crossing pipeline protection.