About this Research Topic
Global rivers transport large quantities of dissolved and particulate matter to the ocean, transform significant amounts of carbon and nutrients en route, and support considerable in situ aquatic production. Global river systems are becoming increasingly impounded, in particular in developing economies where the demands for energy, recreation, and irrigation are increasing rapidly. These dams redistribute seasonal and annual water flows, which causes further changes to the hydrology, ecology, and biogeochemistry in rivers and downstream ecosystems. Most prominently, reservoirs substantially extend water residence time in watersheds, causing enhanced in-stream autotrophy and carbon metabolism, nutrient retention, and greenhouse gas emissions from reservoirs and downstream rivers. These processes are thought to substantially change river systems from passive terrestrial pipes to reactors, yet these changes are not well understood at the watershed scale.
To quantity watershed-scale perturbations by river impoundments necessitates a mechanistic understanding of the cause, strength, and duration of reservoir-specific processes. Considering large seasonal variability in both natural and managed reservoirs, year-round field or modeling research is particularly important. These studies are however relatively rare. The aim of this Research Topic is to gather studies with a particular interest in the effects of reservoirs on river hydrology, biogeochemistry, and ecology, and provide a platform for the aquatic community to present field and/or theoretical investigations on relevant mechanisms and processes. We aim to promote the scientific community's understandings of reservoir-relevant riverine perturbations through these studies.
We are particularly interested in biogeochemical processes that result in enhanced loss or retention of carbon or nutrients (nitrogen, phosphorus, silicon, etc.) in reservoirs. Since various aquatic physical and ecological processes (e.g., eutrophication and related phytoplanktonic and microbial processes) are either causes or consequences of the reservoir biogeochemistry, they are considered highly relevant. We welcome studies that incorporate whole season dynamics or the mechanisms of cascade reservoirs. We also welcome studies from different perspectives or employing different approaches, which include but are not limited to field investigations, remote sensing, statistical or physical modeling, and theoretical studies. Proposed subtopics are listed as follows:
• Biogeochemical perturbations of carbon and nutrients dynamics in reservoirs
• Water column or reservoir bed greenhouse gases emission dynamics and surface emission
• Aquatic microbial community in reservoirs
• Remote sensing of physical, biogeochemical, and ecological processes in reservoirs
• Dam-removal effects on river hydrology and biogeochemistry
• Watershed-scale perturbations by river impoundments
Topic Editor Lee Brown has received financial support from Yorkshire Water Services Ltd. The other Topic Editors declare no competing interests with regard to the Research Topic subject.
Keywords: rivers, reservoirs, biogeochemistry, ecology, hydrology, nutrients, carbon, greenhouse gases, dam removal
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