355 
Hotos 
upare 
with 
ely 
struc- 
aterial 
the 
aiform 
high 
npor- 
tographs 
fast and 
ase. 
moun- 
íistru- 
Lon 
Drtho- 
observation and the precision required. Since the official Swiss data-bank 
is based on a square grid of 100 x 100 m, the use of the same size or an 
easy divisible fraction of it is advisable (50/25 m). For Grevasalvas a 
square grid of 50 x 50 m was selected. 
3. RESULTS 
So far the inventory and mapping procedure for both test areas could be 
carried out for the most important surface features (snow, vegetation, land- 
use, phenology etc.). But additional data-sets in particular of the seasonal 
and yearly changes as well as ground measurements (climatic elements) are 
still needed. The information system for the Grevasalvas test site is estab 
lished and fully operational. The necessary software for the data output in 
form of computer maps is available. Consequently all necessary preparations 
and the basic data-sets for successful ecological studies are completed and 
the remote sensing methods for an easy additional data input are tested. 
Only very selected examples of this inventory phase may be presented 
here, dealing primarily with the interpretation of fast changing surface 
features. Since the methodological approach is rather different for the two 
test sites, the results will be presented separately. 
d ma 
is 
bion 
is 
n cor- 
a 
etc.). 
Ltative 
rical 
. The 
equal, 
photo 
3m, 
ting 
1er 
3.1. Dischma Valley 
Fig. 3 shows a generalized map of the snowmelting process in its dyna 
mics for a "normal" year (i960), e.g. an year of average snowfall and of no 
substantial late snowstorms in spring. The interpretation was carried out on 
b&w photographs of an average scale of 1 : 60'000 and the boundaries were 
transferred onto a map 1 : 10*000. The snowcover is classified into seven 
different categories (100-99» 98-38, 87-63» 62-38, 37-13» 12-2 and 1-0 J /> 
snowcovered land). 
The situation as described was mapped for three different dates.(14.5.60, 
31.5.60 and 22.6.60) during the most important melting period. Fig. 3 inclu 
des only the boundaries between snowcovered and snowfree areas (87 ^ and more 
snowfree area) for the three dates and consequently the zones which got snow- 
free in between two dates, providing an excellent picture of the dynamics in 
volved. 
The combination of the three maps 1 : 10'000 showing the distribution 
of the snowcover in great detail allows an extensive further qualitative and 
quantitative evaluation of the changes in the snowcover and its correlation 
with the relief, exposure and especially the vegetation and phenology (Lit. 
10). In addition the comparison of different specific locations (e.g. an 
altitudinal belt, slopes of the same gradient and the same exposure etc.) 
regarding its relation to snowmelt may be easily evaluated. 
For a further study of the correlation between snowcover and plant com 
munities the melting process for two extreme winters (one with a minimal