This area was chosen as study site because 
the landscape was rather undamaged and 
different kinds of landscape forming pro 
cesses were expected. 
Already in the 17th century part of the 
area has been used for agriculture. The 
first farm in the Amsterdam Waterwork Dunes 
was located in a duneslack called "Haeghs- 
velt",a part of the case study site. There 
were small fields but most of the area was 
grazed by livestock (cattle & sheep). This 
agricultural use continued until about 
1920. figure 2 shows an old map (of 1746) 
with dune plains in agricultural use , the 
Haeghsvelt is one of them . In between the 
dunes are indicated as mole-hills. Nowadays 
we still can recognize the fields surroun 
ded with ditches, indicating that groundwa 
ter reached the surface in those days. 
Another usage of the dunes is the catchment 
of drinking water. The catchment of drin 
king water in the Amserdam Waterwork Dunes 
started in 1853, the channel close to the 
study site was dug in 1887. As groundwater 
catchment exceeded the effective amount of 
precipitation, the groundwatertable dropped 
. The originally wet valleys and dune-rill 
(Gevers,1826) ran dry because groundwater 
table dropped about 5 meters. Figure 3 
shows at the left, the situation in 1916 , 
thirty years after the channel was dug. The 
groundwater table has already dropped three 
to five meters. In 1948 the phreatic level 
dropped to less than two meters above sea- 
level. Since the midfifties the area just 
to the north of the study area is being 
used for the infiltration with riverwater. 
The groundwater level raised again, because 
groundwater catchment no longer exceeded 
the amount of precipitation. 
3 MATERIAL AND METHOD 
The material, available in archives, for 
this study seemed to be of very different, 
but sufficient quality. Five sets of ste 
reoscopic photographs formed an interesting 
time serie (table 1). 
Table 1 Available stereoscopic photomate 
rial . 
year 
scale 
type 
1938 
1:10600 
black & white photo. 
1958 
1:19100 
black & white photo. 
1968 
1: 4000 
black & white photo. 
1979 
1: 4900 
false colour diapos. 
1985 
1: 5100 
false colour diapos. 
The interpretation of aerial photographs 
occured in three main steps ( Zonneveld, 
1979): 
1) Analysis 
detection 
recogniotion and identification 
- delineation 
2) Classification 
3) Field check 
fig. 2 Detail of old map ("Kaartboek van Rijnland", 1746) 
365