Publication Details

Category Text Publication
Reference Category Journals
DOI 10.1016/j.scitotenv.2019.134145
Licence creative commons licence
Title (Primary) Spatial patterns of water quality impairments from point source nutrient loads in Germany's largest national River Basin (Weser River)
Author Yang, S.; Büttner, O.; Kumar, R. ORCID logo ; Jäger, C.G.; Jawitz, J.W.; Rao, P.S.C.; Borchardt, D.
Source Titel Science of the Total Environment
Year 2019
Department ASAM; CHS
Volume 697
Page From art. 134145
Language englisch
Keywords Point source nutrient loads; Dilution; In-stream nutrient uptake; Eutrophication; Hydrological alteration
Abstract We employed the well-established Horton-Strahler, hierarchical, stream-order (ω) scheme to investigate scaling of nutrient loads (P and N) from ~845 wastewater treatment plants (WWTPs) distributed along the river network in urbanized Weser River, the largest national basin in Germany (~46K km2; ~8.4 million population). We estimated hydrologic and water quality impacts at the reach- and basin-scales, at two steady river discharge conditions (median flow, QR50; low-flow, QR90). Of the five WWTPs class-sizes (1 ≤ k ≤ 5), ~68% discharge to small low-order streams (ω < 3). We found large variations in capacity to dilute WWTP nutrient loads because of variability in (1) treated wastewater discharge (QU) within and among different class-sizes, and (2) river discharge (QR) within low-order streams (ω < 3) resulting from differences in drainage areas. For QR50, reach-scale water quality impairment assessed by nutrient concentration was likely at 136 (~16%) locations for P and 15 locations (~2%) for N. About 90% of these locations were lower-order streams (ω < 3). At QR50 and only with dilution, basin-scale cumulative nutrient loads from multiple upstream WWTPs increase impaired locations to 266 (~32% of total) for P. Considering in-stream uptake decreased P-impaired streams to 225 (~27%), suggesting the dominant role of dilution in the Weser River basin. Role of in-stream uptake diminished along the flow paths, while dilution in larger streams (4 ≤ ω ≤ 7) minimizes the impact of WWTP loads. Under QR90 conditions [(QR50/QR90) ~ 2.5], water quality impaired locations will likely double for the basin-scale analyses. Long-term water quality data suggested that diffuse sources are the primary contributors for water quality impairments in large streams. Our data-modeling synthesis approach is transferable to other urbanized river basins and extends understanding of point source impacts on water quality across spatial scales.
Persistent UFZ Identifier
Yang, S., Büttner, O., Kumar, R., Jäger, C.G., Jawitz, J.W., Rao, P.S.C., Borchardt, D. (2019):
Spatial patterns of water quality impairments from point source nutrient loads in Germany's largest national River Basin (Weser River)
Sci. Total Environ. 697 , art. 134145 10.1016/j.scitotenv.2019.134145