341 
Carten- 
_t, wenn 
spektrale 
25 YEARS OF SEQUENTIAL PHOTOGRAPHIC 
MONITORING OF A TIDAL ENVIRONMENT 
id ziemlich 
I. S. Zonneveld*) 
2 er Displays 
erung für 
zusam 
ABSTRACT 
arte der 
rglichen. 
Between 1950'and 1974 photos were made each year of a tidal accrection 
from a high tension pylon with a height of 55 metres. 
The photography was performed as part of the vegetation and landscape 
agrenzungen 
succession studies in a freshwater tidal area 3 Biesbosch 3 situated in the 
ahme einiger 
Southwestern part of the Netherlands (confluence Rhine and Maas). 
2 h Umklas 
The equipment used was very simple: Ordinary commercial cameras 
(25 x 24 mm 3 and 60 x 60 mm) with focal lengths of 50 and 80 3 and 130 mm 
ch, eine 
respectively 3 a rowingboat and canoe and a mental resistance against acrophobia. 
n Unterschieden 
For the evaluation of the material a simple mirror stereoscope and an 
s den Ergeb- 
optical pantograph were used. 
The series of photographs clearly shows the geomorphological process of 
RTS-Daten 
silting up 3 erosion 3 gully formation and lateral shift of accretions. 
ekarten für 
Riant (vegetation-) succession can be followed in rather great detail in 
lgerung ist 
a semi-quantitative way. 
The most important species could be recognized individually. Earlier 
wurde, und 
conclusions made on the plant succession derived from side by side 
ndbarkeit auf 
occurrence 3 could largely be confirmed. Speed and impact of changes caused 
notwendig sind. 
by the changing tidal amplitude 3 due to the dutch "Delta scheme" 3 could 
be followed. 
RÉSUMÉ 
Des photographies ont été faites annuellement , entre 1950 et 1974 3 à partir 
d’un pylône à haute tension haut de 55 mètres 3 pour l’étude de 1’ élévation 
de la hauteur de la marée. 
*) Ass. Prof, in Vegetation Survey and Ecology