TY - JOUR

T1 - A note on using a digital camera to measure suspended sediment load in Maputo Bay, Mozambique

AU - Hoguane, A.M.

AU - Green, Clare

AU - Bowers, David

AU - Nordez, Sonia

PY - 2012/5/1

Y1 - 2012/5/1

N2 - This article explores the possibility of using digital photography to measure the concentration of suspended sediments in coastal water. Photographs of water colour were taken with a commercially available camera at 21 stations in Maputo Bay, Mozambique, using a short tube with one end immersed in the water to remove surface reflection. Surface water samples were collected at the same time and analysed to determine concentrations of chlorophyll-a and phaeopigments (‘total’ pigments), coloured dissolved organic matter, and total and mineral suspended sediment (MSS) concentration. The optics of the water in the bay is dominated by MSS, which absorbs 75% or more of the light in the red, green and blue parts of the spectrum. As the concentration of MSS increases, the proportion of blue light in the water leaving signal decreases and the proportion of red light increases. The ratio of red to blue ‘counts’ measured with the camera correlates well with the MSS concentration (R 2 = 0.71). There is a weaker but statistically significant relationship between total pigments and the ratio of blue to green counts. We conclude that digital photography is an effective and inexpensive method of quantifying suspended material in these waters although the relationship proposed is likely to be site specific

AB - This article explores the possibility of using digital photography to measure the concentration of suspended sediments in coastal water. Photographs of water colour were taken with a commercially available camera at 21 stations in Maputo Bay, Mozambique, using a short tube with one end immersed in the water to remove surface reflection. Surface water samples were collected at the same time and analysed to determine concentrations of chlorophyll-a and phaeopigments (‘total’ pigments), coloured dissolved organic matter, and total and mineral suspended sediment (MSS) concentration. The optics of the water in the bay is dominated by MSS, which absorbs 75% or more of the light in the red, green and blue parts of the spectrum. As the concentration of MSS increases, the proportion of blue light in the water leaving signal decreases and the proportion of red light increases. The ratio of red to blue ‘counts’ measured with the camera correlates well with the MSS concentration (R 2 = 0.71). There is a weaker but statistically significant relationship between total pigments and the ratio of blue to green counts. We conclude that digital photography is an effective and inexpensive method of quantifying suspended material in these waters although the relationship proposed is likely to be site specific

M3 - Article

VL - 3

SP - 259

EP - 266

JO - IEEE Geoscience and Remote Sensing Letters

JF - IEEE Geoscience and Remote Sensing Letters

SN - 1545-598X

IS - 3

ER -