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SYMPOSIUM PHOTO INTERPRETATION, DELFT 1962 
and aerial photographs of the area taken some years before that, provided a 
sequential study of the behaviour of the coast. The final siting of the bund was 
based on the information so obtained. Aerial photography is also being used in a 
sequential sense in the study of silting of the Chenderoh Lake in Perak. 
The Klang Gates Dam 
The ability of a three-dimensional view provided by an aerial photographic 
perspective to furnish greater detail than can be obtained from either a recon 
naissance flight or from an ordinary topographic map, was taken advantage of 
in the Klang Gates Dam project. This dam is located at the Klang Gates gorge 
about eight miles north-east of Kuala Lumpur. The Klang river, emerging 
from a fairly wide valley, crosses the hard rock of the Klang Gates ridge which 
is composed almost entirely of white quartz. This ridge of quartz, which is 
about 500 feet wide at the gorge, can be traced distinctly on the photographs 
for a distance of more than 10 miles. Stereo pairs reveal the prevalent fracture 
patterns in amazing detail. These details, supplemented by those obtained by 
ground survey, furnished the “information regarding the disposition of greatest 
fracturing intensity and consequent weakness, more than adequate for the re 
quirements of dam design” [1]. 
Landslides 
Landslides frequently occur in Malaya. They may vary from the small 
surface slips which temporarily block roads to the calamitous slide which 
occurred last year in Ringlet with the loss of 17 lives. The Ringlet disaster has 
urged photogrammetrists to explore the possibilities of using aerial photo 
graphy for the detection of potential landslides and to see how aerial photo 
graphy may be employed as a tool in the investigation of landslides from the 
point of view of both prevention and control. 
Almost vertical cuttings can be made in virgin and consolidated lateritie soil 
for a height of some 60 feet. If the slopes are left unturfed and undrained, the 
surface runoff soon carves out gullies and other typical erosion features which 
can be clearly identified on aerial photographs. The relative age of a gully 
system is typically indicated by the more developed system of distributaries. 
The homogeneity of the soil is reflected by whether the pattern of the gullies 
is smooth or angular. In steep newly cut slopes, surface slips generally occur 
after a short torrential rain. These result from the weakening of the soil strength 
through saturation of the surface layer. 
If unconsolidated, which is the condition of the soil dumped indiscriminately 
onto the top of existing slopes in terracing for construction, surface erosion is 
accompanied by considerable seepage of water into the soil. The material, 
being loose, is more porous. Slips therefore tend to occur along the lubricated 
planes of contact between the new fill and the firmer and more impervious 
original slopes.