B. Merz et A. Bardossy, Effects of spatial variability on the rainfall runoff process in a small loess catchment, J HYDROL, 213(1-4), 1998, pp. 304-317
Numerous field experiments have revealed that hydrological processes and pa
rameters can show considerable spatial variability. When modelling the rain
fall runoff process, the influence of this variability on the runoff should
be assessed. For regionalization purposes, it is an important question if
and how this variability is reflected in the behaviour on a larger scale. A
quasi-three-dimensional, process-oriented model is used to understand the
influence of spatial variability on the runoff behaviour. The study area, "
Neuenburger Pfad", is a small loess catchment in southwestern Germany. Beca
use of low infiltration capacity of the loess soil, runoff is produced by i
nfiltration excess overland flow. Three examples are presented which elabor
ate on the effects of different types of spatial variability. The first exa
mple shows that an agricultural road plays a crucial role in the runoff beh
aviour of the investigated catchment. The second example studies the role o
f the spatial distribution of soil parameters. It demonstrates the importan
ce of structured variability in heterogeneous fields. Purely random fields
result in hydrographs similar to the homogeneous case, whereas fields with
structured variability yield very different runoff. The third example is co
ncerned with the effects of different soil moisture interpolations, which s
erve as initial state for the runoff model. The examples presented show tha
t spatial variability can have a dominant influence on the rainfall runoff
behaviour. For sound modelling, a close inspection of the particular catchm
ent characteristics is necessary. Structured variability should be included
in hydrological models because of the larger influence compared to stochas
tic variability. To understand the extent and the significance of catchment
variability, an interdiciplinary teamwork should be fruitful. (C) 1998 Pub
lished by Elsevier Science B.V. All rights reserved.