In flowing water, turbidity curtains should be placed in which orientation concerning the flow direction?

The correct orientation for turbidity curtains in flowing water is parallel to the flow. This alignment is crucial to effectively contain and manage sediments and other particulates being carried by the water. When the curtain is placed parallel to the flow, it can effectively trap the sediment and minimize its dispersion downstream.

By positioning the turbidity curtain in this way, it allows for the natural flow to direct contaminants towards the curtain, where they can be captured more efficiently. This setup enhances the sediment control function of the curtain, ensuring that the turbidity is reduced and that water quality in the surrounding area is protected.

The other orientations would not provide the same level of effectiveness. For instance, a perpendicular placement would obstruct the flow but might allow sediment to pass underneath or to the sides. A diagonal orientation could also lead to gaps in coverage, making it less effective in containing turbidity. Surrounding the flow entirely is impractical, as it would create barriers that could disrupt natural waterways and potentially lead to unintended consequences in water movement. Thus, a parallel orientation is clearly the most practical and effective choice for turbidity curtains in flowing water.