Alkema, Dinand 
  
Geomorphologic impact assessment 
A lot of authors have proposed methodologies to evaluate geomorphologic assets and hazards. In general they are based 
on a detailed geomorphologic map which, in combination with additional information on e.g. lithology, hydrogeology, 
slope angle and of historic events, allows a quantitative assessment of the assets and the dynamics of the active 
processes in the area of interest. They permit to evaluate the direct impact of the development on the geomorphologic 
assets. These methodologies are not sufficient to assess the indirect impact and the risks posed by geomorphologic 
processes and more rigorous techniques need to be applied. Indirect impact, risk, direct risk and indirect risk are the 
result of geomorphologic processes or the result of changes in the geomorphologic processes due to the development. 
To be able to forecast the dynamics of the geo-morphologic processes and their interaction with the development, more 
fundamental knowledge about the mechanics of the geomorphologic system is required. It is here that system analysis 
can play major role. 
3 GEOMORPHOLOGY AS A SYSTEM ANALYSIS 
Geomorphologic processes are too complex to be studied as a whole. For a better understanding it is necessary to study 
separately the catchment basin system, the slope system, the fluvial system, etc., that can be understood by (a group of) 
experts. This will lead to an understanding of how that specific system functions. Then the task awaits to integrate all 
this knowledge into a integrated picture of the total. System analysis offers a framework to define causes, mechanisms 
and effects of the processes in terms of mass and energy. But the problem is to integrate some of these open systems 
into a synthesis that represents the complexity of the geomorphologic processes with their interactions. 
Conceptual model 
An integrated system synthesis can be represented by a conceptual model. The conceptual model is the assemblage of 
all possible elements that may be of importance for a geomorphologic system and through links one can indicate that in 
some way the various elements are related or interact (fig. 1). Some links may indicate cause-effect relations, according 
to mass and energy. A correct conceptual model helps to define the system, and functions as discussion tool for those 
scientists that are involved in the analysis. In the study of a geomorphologic system it is necessary to link it with the 
anthropic system. For each element one can ask the question “why is this element important for my task?”. This will 
ultimately lead to the recognition that we need data about each element because they affect human concerns — things 
that we care about, like human life and health, but also economic and environmental considerations. The construction of 
a conceptual model is very important. Those elements should be included in the model that are sensitive to the 
development and that have a link with human concerns: if the development changes the characteristics of an element 
then eventually it will affect things we care about. 
(well-being J \_congestion_~ ; in quanti jn quality 
^ ^ A 
Loss of industrial I" Loss of agricultural 
Concerns roads cen sa 
A A 
Sensitivity | ia | | ze Infrastructure | Industry Agriculture 
A N R À N detto. A A k 
\ Damageto | I X 
Spread of constructions : Magnitud | 
i Soil loss/ > 
ila Material deposition X | Duration 
S Y A A 
       
           
      
" Decrease Decrease 
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
Groundwater 
table 
  
  
  
  
  
  
  
   
| Satellite imaged 
Input ....Aenal Phot 
x1 
  
Fieldwork 
  
Fig. 1: An example of a conceptual model. 
  
International Archives of Photogrammetry and Remote Sensing. Vol. XXXIII, Part B7. Amsterdam 2000. 55