Study on morpho- and hydro-dynamics of multi-box culverts

Abstract

Culverts are used to convey a large range of flow rates and sediment load through road embankments. They customarily are designed to convey flow events having a 50-year return period. Often times, the multi-barrel culverts are preferred as they require a lesser upstream headwater elevation compared with single-barrel culverts. Most of the time, however, culverts convey flows that are of lower velocity and lesser depth than the design flows. During the transitions from high to low flows sediment deposition inherently occurs in the upstream transitioning the stream to culvert cross-section. Repetition of these flow transitions over the time results in the increase of the sediment deposits that often become "stabilized" due to the growth of vegetation, hence reducing permanently the capacity of culverts to handle large flows. The present paper investigates details of the mechanics of the formation of the sediment deposits in the upstream vicinity of the culverts and mitigation designs that ensure an efficient, hydraulic-driven cleaning effect.