2004 
  
tude 
two 
F in 
y of 
Was 
n 
Qe 
1€ 
W / 
cate 
s of 
not 
zen. 
) is 
aily 
S at 
vith 
ern 
the 
vith 
ded 
oler 
the 
rin 
one 
X a 
the 
er» 
lore 
The 
ne. 
arp, 
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B2. Istanbul 2004 
  
  
Figure 8 : orientations spectrum for DTM of the Vosges (Data 
from IGN’s BD ALTI®, 2003) ; each circle represents 1% of 
the total number of points in the DTM, steps of 7.5°. 
4.3.3 Orientation modes : Tt is interesting to know the 
mode(s) of orientation maps (figure 9) ; a visual study can 
provide an approximate determination. To complete the study 
of a graph, let us visualize the distribution function of the 
indicator (cumulative graph). 
ge 
| 
  
— 
|; up Y | 
| 
| 
| 
: | 
| 
| | 
; à + J nt ia : j 
Figure 9 : DTM of Briangon- Orientation graphs (left), data 
from IGN's BD TOPO® 2003. This function has a very clear 
profile ; the mode(s) correspond(s) to the maximum number of 
slope points ; distribution function of the orientations (right) 
5. CONCLUSION 
There exists a dynamic equilibrium which links the shapes of 
the terrain to the geomorphological processes which give rise to 
them ; thus, slopes measured in the field are simultaneously the 
result of a long chain of previous evolutionary processes as well 
as the result of actual processes currently in progress. Terrain 
shapes and evolutionary processes of slopes interact with to 
such a degree that it is difficult to disassociate them ; The 
present study is designed to justify the usefulness of 
geomorphometry as an interdisciplinary field rooted in 
hydrology, engineering science and geomorphology, from the 
social sciences. 
If the interpretation of terrain shapes cannot be disassociated 
from vegetation cover, climate and the nature of the ground, 
others seem more independent of this interface, such as geology 
and climate. In any case, this interface is associated with a 
surface that is studied for its own sake for the role it plays. This 
‘manner of proceeding requires the identification of irregularites 
on the basis of reliable indicators, constructed from models 
satisfactorily representing the surface of the ground. 
Geomorphometry does not pretend to understand the shapes of 
the relief. It can contribute valuable information due to the 
complex measurements it can provide with the objectivity of a 
statistical method. Nevertheless, for a measurement to be 
useful, the reality to be measured must first be defined and then 
be measurable with an acceptable approximation in relation to 
the objects studied. This involves sampling theory which is 
based on Shannon’s theorem. The difficulty in geomorphometry 
815 
consists in avoiding surplus information by adopting grid links 
which are too small, susceptible to interpolation static, which 
may also shrink the number of samples in the zones studied and 
may impoverish the statistical properties linked to the terrain 
shapes. » 
The authors have begun to program numerous indications 
around the Research Systems Incorporated’s Rivertools 
software. The task undertaken will be prolonged to result in a 
complete set of geomorphometric indicators chich can be used 
in geographic information systems . They will be added to the 
data already available in IGN’s Large Scale Referential, called 
RGE, to complete other environmental or thematic indicators 
and to promote the development of a new geography based on 
traditional human foundations and numerical indicators such as 
those presented above. 
References and Selected Bibliography : 
Deffontaines B., 1990. Développement d'une méthodologie 
morphostructurale et morphonéotectonique ; Analyse des 
surfaces enveloppes, du réseau hydrographique et des modèles 
numériques de terrain ; Application au Nord Est de la France. 
Thèse de Géologie structurale et de Télédétection, Université 
Paris VI, 1991, 194 p. 
Deffontaines B., Chorowicz J., 1991. Principle of drainage 
basin analysis from multisource data, Application to the 
structural analysis of the Zaire Basin, Tectonophysics, 194 : 
237-263. 
Depraetere, C., 1984a. Etudes | géomorphométriques 
comparatives en Afrique du Sud : applications hydrologiques et 
géomorphologiques, Thèse de 3°”° cycle en géographie, 
Université. Paris-Sorbonne, PIV. 
Depraetere, C. 1984b. Exemples d'Analyses 
Géomorphométriques dans les Appalaches à partir de Modéles 
Numériques de Terrain, Physio-Géo, n°17, pp: 49-76. 
Derruau M., 1974. Précis de géomorphologie, Masson et Cie, 
6ème Edition, Paris, 453 p., 171 fig., 62 pl. h.t., (chapitre XI: 
pp--117-122). 
Dewolf Y., 1982. Cours de géomorphologie, Univ. Paris VII, 
90p. 
Dufour, H. M., et Abgrall, F., 1988a. Eléments Remarquables 
du Relief : Définitions Numériques Utilisables, Bulletin CFC, 
n°95 
Dufour, H. M., 1988b Quelques idées générales concernant 
l'établissement et l'amélioration des Modéles Numériques de 
Terrain, Bulletin. d information. de l'I.G.N. 88/1. 
Dupéret, A., Contribution des MNT à la Géomorphométrie, 
Rapport de DEA SIG, Ecole Nationale des Sciences 
Géographiques et CNRS, Septembre 1989, 54p. 
Joly F., 1997. Glossaire de géomorphologie, Base de données 
sémiologiques pour la cartographie, Coll. U, Armand. Colin 
Ed., 325p.