Quantifying the effectiveness of superposed roughness elements to reduce dust emissions at the Salton Sea using computational fluid dynamics simulations

The Salton Sea region faces significant air quality challenges, with particulate matter ≤10 μm (aerodynamic diameter, i.e., PM10) concentrations exceeding regulatory standards for 24-hour mean values established by the US Environmental Protection Agency (150 µg m⁻³) and the State of California (50 µg m⁻³). The lake’s receding shoreline has exposed areas of lakebed, creating potential sources for wind-blown dust. In response, the Salton Sea Management Plan aims to construct habitats and implement dust suppression strategies for areas expected to be exposed by 2028. A key component of this effort is to use roughness elements superposed on the exposed lakebed to mitigate dust emissions by reducing wind shear and inhibiting saltation. This study uses computational fluid dynamics to analyze array effectiveness across multiple wind directions for a defined roughness element size, density (number per hectare), and distribution (nominally a staggered array). In contrast to other studies of roughness arrays, we utilize roughness element locations and orientations from an existing array at the Salton Sea and perform a surface integral over the exposed surface to predict emissions. A relation between mass flux of PM10 and shear stress was used in the post-processing of simulated wind shear on the surface, to estimate the total emissions of PM10 before and after the installation of the roughness array. Our findings demonstrate a significant reduction in both shear stress on the intervening surface and dust emissions compared to the same area without the roughness, a result that is further supported by measurements. This research underscores the potential of engineered roughness arrays to improve air quality in regions affected by dust emissions.