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The nutrient discharges from point and
diffuse sources in more than 200 German river
basins were estimated for the periods 1983–1987 and
1993–1997 employing the MONERIS model. This
model distinguishes between six diffuse pathways
and point source emissions from waste water treat-
ment plants and direct industrial discharges. It was
estimated that the total nitrogen input into the
German river systems amounts to about 819,000 t N year^–1
in the period 1993 to 1997. These emissions have decreased since the mid-eighties by
about 266,000 t N year^–1, mainly caused by the reduction of point discharges. For phosphorus the
emissions have been reduced by 56,290 t P year^–1 and amount to 37,250 t P year –1 in the period 1993–
1997. Based on emission data a retention module estimates riverine nutrient loads. The comparison of
the model output with the observed loads shows a deviation as low as 30% and 50% for nitrogen and
phosphorus, respectively. The regional resolution of the model indicates the relative importance of dif-
ferent pathways for phosphorus and nitrogen input into river systems.
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