| Title: | A method to assess instream water quality - the role of nitrogen entries in a north German rural lowland catchment |
| Authors: | Schmalz, B., K. Bieger and N. Fohrer |
| Year: | 2008 |
| Journal: | Advances in Geosciences |
| Volume (Issue): | 18 |
| Pages: | 37-41 |
| Article ID: | |
| DOI: | 10.5194/adgeo-18-37-2008 |
| URL (non-DOI journals): | |
| Model: | SWAT |
| Broad Application Category: | hydrologic and pollutant |
| Primary Application Category: | nitrogen cycling/loss and transport |
| Secondary Application Category: | tile drainage effects and/or processes |
| Watershed Description: | 50 km^2 Kielstau River, which is located in a lowland area of the State of Schleswig-Holstein in northern Germany. |
| Calibration Summary: | |
| Validation Summary: | |
| General Comments: | |
| Abstract: | The objective of this study was the detection
and assessment of nutrient entry pathways in a complex
mesoscale lowland catchment. The central aim was the development
of a transferable method for an efficient estimation
of instream water quality in rural environments. The
investigated Kielstau catchment with a size of approximately
50 km^2 is located in the North German lowlands. Land use
is dominated by agriculture as well as pasture and is characterised
by extensive artificial drainage systems. Additionally
wastewater treatment plants influence the river water quality.
Six measuring campaigns were carried out over the period
of one year. Each time, water quality was assessed at 16
locations along a 12 km longitudinal transect of the stream
to consider the influence of each tributary or inflow. The results
showed that the applied measuring method was useful to
assess nutrient entry pathways into surface waters from diffuse
and point sources. Some tributaries increased the main
stream NO3-N concentrations especially in autumn. Using
a German classification system (LAWA, 1998), the NO3-
N results can mostly be assigned to water quality class III
(heavily contaminated). Water balance and nitrate loads were
modelled with the river basin scale model SWAT (Soil and
Water Assessment Tool, Arnold et al., 1998). The measured
and modelled discharges showed a good correlation. While
nitrate load range and dynamics are well represented during
the summer periods, they show a poor correlation during the
winter period. |
| Language: | English |
| Keywords: | |