Annual water, sediment, nutrient, and organic carbon fluxes in river basins: A global meta‐analysis as a function of scale

Mutema, M and Chaplot, V and Jewitt, G and Chivenge, P and Bloschl, G (2015) Annual water, sediment, nutrient, and organic carbon fluxes in river basins: A global meta‐analysis as a function of scale. Water Resources Research, 51 (11). pp. 8949-8972. ISSN 0043-1397

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Process controls on water, sediment, nutrient, and organic carbon exports from the landscape through runoff are not fully understood. This paper provides analyses from 446 sites worldwide to evaluate the impact of environmental factors (MAP and MAT: mean annual precipitation and temperature; CLAY and BD: soil clay content and bulk density; S: slope gradient; LU: land use) on annual exports (RC: runoff coefficients; SL: sediment loads; TOCL: organic carbon losses; TNL: nitrogen losses; TPL: phosphorus losses) from different spatial scales. RC was found to increase, on average, from 18% at local scale (in headwaters), 25% at microcatchment and subcatchment scale (midreaches) to 41% at catchment scale (lower reaches of river basins) in response to multiple factors. SL increased from microplots (468 g m−2 yr−1) to plots (901 g m−2 yr−1), accompanied by decreasing TOCL and TNL. Climate was a major control masking the effects of other factors. For example, RC, SL, TOCL, TNL, and TPL tended to increase with MAP at all spatial scales. These variables, however, decreased with MAT. The impact of CLAY, BD, LU, and S on erosion variables was largely confined to the hillslope scale, where RC, SL, and TOCL decreased with CLAY, while TNL and TPL increased. The results contribute to better understanding of water, nutrient, and carbon cycles in terrestrial ecosystems and should inform river basin modeling and ecosystem management. The important role of spatial climate variability points to a need for comparative research in specific environments at nested spatiotemporal scales.

Item Type: Article
Divisions: RP-Resilient Dryland Systems
Uncontrolled Keywords: climate, spatial scale, organic carbon and nutrient erosion, sediments, water pollution, runoff coefficient, organic carbon fluxes, meta-analysis, soil erosion
Subjects: Others > Soil
Others > Soil Science
Others > Climate Change
Others > Water Resources
Depositing User: Mr Ramesh K
Date Deposited: 24 Jul 2018 08:36
Last Modified: 24 Jul 2018 08:36
Official URL:
Acknowledgement: Data used in the current analyses were obtained free of charge from cited literature, and we acknowledge generating secondary data from primary sources in some instances to suit our requirements. The research leading to these results has received funding from the European Community’s Seventh Framework Programme (FP7/2007-2013) under the WHaTeR project (Water Harvesting Technologies Revisited) grant 266360. We would also like to thank the Austrian Science Fund (project P 23723-N21) and the ERC Advanced grant ‘‘Flood Change’’ for financial support. We are also grateful for the comments and suggestions from the journal Editors and three anonymous reviewers.
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