Precipitation
Dominates Interannual Variability of
Riverine Nitrogen Loading across the Continental United States
Eva Sinha
Anna M. Michalak
10.1021/acs.est.6b04455.s001
https://acs.figshare.com/articles/journal_contribution/Precipitation_Dominates_Interannual_Variability_of_Riverine_Nitrogen_Loading_across_the_Continental_United_States/4223871
Excessive
nitrogen loading to waterways leads to increased eutrophication
and associated water quality impacts. An understanding of the regional
and interannual variability in nitrogen loading and associated drivers
is necessary for the design of effective management strategies. Here
we develop a parsimonious empirical model based on net anthropogenic
nitrogen input, precipitation, and land use that explains 68% of the
observed variability in annual total nitrogen flux (<i>Q</i><sub>TN</sub>) (76% of ln(<i>Q</i><sub>TN</sub>)) across
242 catchment years. We use this model to present the first spatially
and temporally resolved estimates of <i>Q</i><sub>TN</sub> for all eight-digit hydrologic unit (HUC8) watersheds within the
continental United States (CONUS), focusing on the period 1987–2007.
Results reveal high spatial and temporal variability in loading, with
spatial variability primarily driven by nitrogen inputs, but with
interannual variability and the occurrence of extremes dominated by
precipitation across over three-quarters of the CONUS. High interannual
variability and its correlation with precipitation persist at large
aggregated scales. These findings point to a fundamental challenge
in managing regions with high nutrient loading, because these regions
also exhibit the strongest interannual variability and because the
impact of changes in management practices will be modulated by meteorological
variability and climatic trends.
2016-10-22 00:00:00
CONUS
High interannual variability
water quality impacts
Q TN
HUC
anthropogenic nitrogen input
Continental United States Excessive nitrogen loading
Riverine Nitrogen Loading
Precipitation Dominates Interannual Variability
interannual variability
eight-digit hydrologic unit
242 catchment years