TITLE:
Evaluation of Different Topographic Parameters Extracted from the Digital Elevation Measurements with the Use of Geostatistical Interpolation Methods
AUTHORS:
Fahmy F. F. Asal
KEYWORDS:
Topographic Parameters, Gradient Slope, Aspect Slope, Shaded Relief, Contourline, Profiling, Ordinary Kriging Models
JOURNAL NAME:
International Journal of Geosciences,
Vol.14 No.12,
December
29,
2023
ABSTRACT: Gradient slope, aspect slope, profiling and
contourlines are important topographic parameters that can be derived from
digital elevation data obtained from different sources with exploitation of
different interpolation techniques. Geostatistical interpolation methods such
as ordinary kriging models constitute reliable alternatives to deterministic
approaches in creation of continuous surface models from discrete elevation
data. This research aimed at extraction, analysis, and evaluation of different
terrain parameters elevation measurements with the use of different ordinary
kriging models including the linear model, the circular model, the spherical
model, the exponential models, and the Gaussian model. Different ordinary
kriging models under ESRI ArcView 3.3 package along with its 3D analyst and
Spatial analysis extensions have been exploited in extraction of gradient slope
maps, aspect slope maps, and hillshade maps in addition to contourline maps
from a sample of elevation data. Visual analysis of the gradient slope maps
shows great similarities between the slope maps from the linear, circular,
spherical, and exponential OK models, however, that from OK Gaussian models
look very different as different sizes and arrangements of the colour patches,
referring to different tones and different textures where smooth tones and
smooth textures dominate the gradient slope map from the OK Gaussian model.
Thus, gradient slope degradation and smoothing are considerably high in the
gradient slope map from Gaussian model compared to the slope maps from the
other four OK models. Also, the mean slope in the Gaussian model records the
lowest value with the lowest value of the standard deviation of slopes in the same
map reflecting less structured and highly smoothed gradient slope map compared
to the slope maps from the other OK models. Thus, similar sizes of the colour
patches and similar tones and similar texture dominate the different aspect
slope maps. This is not the case in Figure 2(e) which depicts the aspect slope map
extracted with the use of the Gaussian OK model where the smooth colour
patches, smooth tones and smooth textures can be observed. Also, the Aspect
map, hillshade map and the contourline map from Gaussian OK model are visually
and statistically different from their corresponding maps created with the
other four OK models. Finally, analysis of extracted two groups of profiles
shows that the profiles extracted with the use of linear, circular, spherical,
and exponential OK models run close and show highly corrugated and varied
terrain. This is different from the profiles with the use of the Gaussian model
which are less corrugated and tend to smooth and approximate different parts of
the terrains.