Thirdly, the multiplication of a concentration of suspended-sediment or a solute with the stream discharge gives the mass of that suspended or dissolved constituent moved over time. Such calculations are important in erosion studies, nutrient budget estimation, and pollution studies. The choice of method depends on the characteristics of the stream and on the application.
Some rivers also have large changes in velocity across the river channel.
This cannot be corrected, so the more accurate current metering method is recommended. Braystoke' current meter and counter. Current metering is an accurate method of river gauging except where the river is very shallow. Under such conditions, an alternative method of dilution gauging can be used. Two approaches to dilution gauging can be used - 'constant injection method' and the 'integration or gulp injection method'.