The effect of colour depth and image resolution on laboratory scale study of aquifer saltwater intrusion

Georgios Etsias, Gerard Hamill, Eric Benner, Jesus Fernandez Aguila, Mark McDonnell, Raymond Flynn

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Increased water consumption combined with the effects of sea level rise and change in rainfall patterns have intensified seawater intrusion in coastal aquifers. Sandbox setups have been utilized over the years to recreate saline intrusion on a laboratory scale and study the mechanisms of this phenomenon. Recreating saltwater concentration fields from light intensity values is a widely applied image analysis practice in such investigations. The current paper investigates the effect of image colour depth and resolution on this procedure. Glass beads of three different diameters were utilized to recreate three homogeneous and one heterogeneous aquifer in a sandbox setup. High resolution images of saltwater intrusion were acquired using a digital camera. From these images, new ones with modified colour depth (16-bit and 8-bit) and smaller resolution were reconstructed. Deriving regression coefficients for the 16-bit experimental images was 36% ~ 51% faster than doing so for their equivalent 8-bit versions. Nevertheless, utilizing lower colour depth images did not lead to a significant increase in the regression error, constituting their use a viable alternative in cases where data storage limitations apply. Smaller versions of the 16-bit experimental images were processed to derive saltwater concentration flow fields. These fields were compared with those of the original data, and the difference between the basic saline intrusion characteristics was quantified. The toe length of the intruding wedge, the width of the mixing zone and the angle of intrusion were calculated for all four downscaled images. The relative difference from the original images for each parameter is up to 0.36%, 1.63% and 0.35% respectively. This indicates that lower resolution experimental images can be employed to derive accurate estimations of the basic saltwater intrusion characteristics, while minimizing processing time.
Original languageEnglish
Number of pages5
Publication statusPublished - 27 Aug 2020
EventCivil Engineering research in Ireland 2020 -, Cork, Ireland
Duration: 27 Aug 202028 Aug 2020


ConferenceCivil Engineering research in Ireland 2020
Internet address


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