In situ measurements of rapidly fluctuating,high sediment concentrations

A new instrument — an almometer — has been developed which measures, instantaneously and continuously, changes in the vertical density distribution of sediment. The almometer consists of two acrylic cylinders, one contains a fluorescent lamp, the other 64 photo-electric cells placed at 1 - or 2-cm intervals. These two tubes are anchored perpendicular to the bottom 30 cm apart.The amount of sediment that can be measured ranges from 10 to 500 g of sediment per liter of water. Calibration shows that differences in sediment size or mineralogy have little effect on the concentration resistance relationship if the size mean is within the sand range and the sediment is not monomineralic.