Optical Water Quality of Inland Waters: A Landscape Perspective

Abstract

Optical water quality (OWQ) relates the composition of waters to their light transmission and thereby light availability for aquatic plants, visual range for aquatic animals, and suitability for recreational uses. This fundamental role of OWQ has led to numerous studies on the optical properties in rivers and lakes, which we overview here with a landscape perspective. International examples illustrate how the kinds and amounts of light-attenuating substances depend on landscape features on scales ranging from the river reach to the orientation of mountain ranges. OWQ is profoundly affected by increased nutrient discharges and sediment mobilization from human activities such as agriculture. Proper monitoring of OWQ is needed to fully understand and address these consequences. Remote sensing has potential for broad-scale surveys of OWQ, although currently its applications to inland waters are limited by low spatial resolution. A better understanding of OWQ will advance water management and remote sensing capabilities, as well as provide further insight into water quality impacts associated with global changes in climate, energy use, and land use.