Research from the past four years, mostly dealing with estimating monthly and annual loads, is emphasized. However, because this topic has not appeared in previous IUGG reports, some research prior to 1990 is included. The motivation for studying sediment transport has shifted during the past few decades. In addition to its role in filling reservoirs and channels, sediment is increasingly recognized as an important part of fluvial ecosystems and estuarine wetlands.
Nutrients play a critical role in determining the ecology of rivers, lakes and estuaries.
Scientists, regulators, and resource managers increasingly want to understand nutrient fluxes. Tools for estimating sediment and nutrient transport are changing. Recent research has been directed at developing methods for reducing the number of samples required to obtain acceptable load estimates. A motivation for developing these methods is economics. Such sampling programs appear to be increasingly vulnerable to government cost-cutting.