Anthropogenic impacts on global organic river pollution

Organic pollution of rivers by wastewater discharge from human activities negatively impacts people and ecosystems. Without treatment, pollution control relies on a combination of natural degradation and dilution by natural runoff to reduce downstream effects. To implement integrated water management for organic river quality at global scale, a crucial step is to develop a spatial analysis of organic river pollution threats. This thesis provides for the first time a quantitative picture of the global sanitation crisis through its impact on organic river pollution from the threats of (1) increasing wastewater discharge due to urbanization and intensification of livestock farming, and (2) reductions in river dilution capacity due to climate change and water extractions. Using in-stream Biochemical Oxygen Demand (BOD) as an overall indicator of organic river pollution, historical (2000) and future (2050) BOD concentrations in global river networks are calculated. Despite significant self-cleaning capacities of rivers, the number of people affected by organic pollution (BOD È 5 mg/l) is projected to increase from 1.1 billion in 2000 to 2.5 billion in 2050. With developing countries disproportionately affected, the results point to a growing need for affordable wastewater solutions.