| Title: | Regionalization of meso-scale physically based nitrogen modeling outputs to the macro-scale by the use of regression trees |
| Authors: | Künne, A., M. Fink, H. Kipka, P. Krause and W.-A. Flügel |
| Year: | 2012 |
| Journal: | Advances in Geosciences |
| Volume (Issue): | 31 |
| Pages: | 15-21 |
| Article ID: | |
| DOI: | 10.5194/adgeo-31-15-2012 |
| URL (non-DOI journals): | |
| Model: | J2000-S |
| Broad Application Category: | pollutant only |
| Primary Application Category: | regionalization of input parameters |
| Secondary Application Category: | nitrogen cycling/loss and transport |
| Watershed Description: | 190 km^2 Helme, 850 km^2 Upper Gera and 230 km^2 Lossa Rivers, located in the State of Thuringia in east central Germany. |
| Calibration Summary: | |
| Validation Summary: | |
| General Comments: | |
| Abstract: | In this paper, a method is presented to estimate
excess nitrogen on large scales considering single field processes.
The approach was implemented by using the physically
based model J2000-S to simulate the nitrogen balance
as well as the hydrological dynamics within meso-scale test
catchments. The model input data, the parameterization, the
results and a detailed system understanding were used to generate
the regression tree models with GUIDE (Loh, 2002).
For each landscape type in the federal state of Thuringia a
regression tree was calibrated and validated using the model
data and results of excess nitrogen from the test catchments.
Hydrological parameters such as precipitation and evapotranspiration
were also used to predict excess nitrogen by
the regression tree model. Hence they had to be calculated
and regionalized as well for the state of Thuringia. Here the
model J2000g was used to simulate the water balance on the
macro scale. With the regression trees the excess nitrogen
was regionalized for each landscape type of Thuringia. The
approach allows calculating the potential nitrogen input into
the streams of the drainage area. The results show that the
applied methodology was able to transfer the detailed model
results of the meso-scale catchments to the entire state of
Thuringia by low computing time without losing the detailed
knowledge from the nitrogen transport modeling. This was
validated with modeling results from Fink (2004) in a catchment
lying in the regionalization area. The regionalized and
modeled excess nitrogen correspond with 94 %.
The study was conducted within the framework of a
project in collaboration with the Thuringian Environmental
Ministry, whose overall aim was to assess the effect of agroenvironmental
measures regarding load reduction in the water
bodies of Thuringia to fulfill the requirements of the European
Water Framework Directive (Base et al., 2007; Fink,
2006; Fink et al., 2007). |
| Language: | English |
| Keywords: | |