Lowland areas are characterised by specific properties, such as flat
topography, low hydraulic gradients, shallow groundwater, and high potential
for water retention in peatland and lakes. The investigated mesoscale
catchments Stör, Treene and Kielstau are located in Northern Germany
within lowland areas. Covering areas from 50 to 517 km2, these rural
catchments have sandy, loamy and peaty soils and are drained in high
fraction by open ditches and tile drainage. Using the river basin model
SWAT, sensitivity analyses were carried out through an automatic routine
that is based on the Latin-Hypercube (LH) and a One-factor-At-a-Time (OAT)
sampling. The objective of this study is to investigate how specific
landscape features influence the model behaviour. There are two research
questions: a) What are the most sensitive parameters in the studied lowland
catchments? b) What differences occur between these landscape features in
comparison to mountainous or low mountain range catchments?
The results show that groundwater and soil parameters were found to be most
sensitive in the studied lowland catchments and they turned out to be the
most influential factors on simulated water discharge. The most sensitive
parameter was the threshold water level in shallow aquifer for baseflow
(GWQMN). In contrast, many studies of mountainous or low mountain range
catchments show that the most sensitive parameters were the surface runoff
parameters. |