Geoscience Reference
In-Depth Information
Table 14.8
Changes of parameters of modelled relief in different relief types of the scale 1:25,000
with the basic contour line interval 5 m (source: the authors)
3
High-quality DEM
Low-quality DEM
2D
area
[km
2
]
LCL
[km]
3D area
[km
2
]
∗
3D area
[km
2
]
∗
NOP
∗
NOP
∗
Relief type
RAS [m]
Flat land
0-30
9.370
4
4.000
10
15
4.004
0
20
Hilly area
30-150
103.258
4
4.051
1
20
4.070
0
20
Highland
150-300
190.690
4
4.158
5
30
4.298
0
20
Mountain area
300-600
278.485
4
4.288
5
15
4.576
0
20
14.3 Terrain Sensitivity
Terrain sensitivity is the ability of digital relief expression to influence the results of
spatial modelling, which includes influence by the earth's surface. Terrain sensitivity
in models of spatial phenomena depend on all stages of surface processing, starting
with the selection of source data, through to determination of resolution, interpola-
tion methods and their parameters, etc. It is caused by generalised expression of the
earth's surface in digital data structures (Voženílek, 2002a).
Physical geographic models also include various derived parameters of the
earth's surface, e.g. morphometric characteristics and shape of relief. This is the
reason why a number of studies (e.g. Etzelmuller, 2000; Wolock & McCabe, 2000;
Tucker, Catani, Rinaldo, & Bras, 2001) discuss the suitability of using source data
for relief expression. However, they take into account generalised sources of altimet-
ric data (contour lines) whereas to express relief more accurately and to decrease
the influence of inaccurately expressed relief it is necessary to use hypsometric
representation as close to primary sources of altimetric data as possible (Schoorl,
Sonneveld, & Veldkamp, 2000).
14.4 Influence on Modelling Physical Geographic Phenomena,
Using the Example of Erosion Processes
Development of modelling of erosion processes currently clearly heads towards
mathematical expression of subprocesses leading to soil erosion and towards imple-
menting such a model in the GIS environment. From the point of view of acquiring
input information the GIS is becoming an essential source. In the area of acquiring
data about relief (inclination, orientation, slope length, curvature and drained areas)
DEMs represent a dominant development environment. The speed and accuracy of
calculation is crucial. Remote sensing is a source of further information, concern-
ing especially land use and seasonal changes in soil qualities. Taking into account
the specificity of some data it is necessary to acquire them by field research, or
potentially by laboratory work.
Search WWH ::
Custom Search