351 
3h today 
resour- 
Two specific test sites are located within the valley. The first one 
was established for hydrological studies by the Swiss Institute for Snow 
and Avalanche Research, Weissfluhjoch-Davos, to analyse the water balance 
based on the snowpack, runoff from snowmelt etc. (Lit. 2). The second one of 
about 10 hectares belongs to the Swiss Forest Experiment Station to study 
conser 
is. as 
a thou- 
c and 
systems 
problems of reforestation along the timber line in an avalanche-danger zone. 
Extensive measurements on the micro- and local climate, snowpack, vegetation, 
soils, phenology etc. have been carried out inside and outside the specific 
test site for more than ten years (Lit. 3-5). In cooperation with the Depart 
ment of Geography, University of Zürich, vegetation and land-use mapping and 
its changes are carried out especially in relation to the snowmelting pro 
cess (Lit. 6). 
ears as 
i effects, 
is the 
3 of bio- 
1.2. Grevasalvas test site 
lain vari- 
to a 
ete sen- 
Lve 
This test area is located on the sun exposed slope of the upper Enga- 
dine, high above the lake of Sils. It includes part of the upper subalpine 
(forest and meadows), alpine (pastures) and nival belt (snow and rocks) 
between 1'800 and 2’950 m. Three small and today only temporarily inhabited 
hamlets are situated in the area. 
Grevasalvas forms a small and clearly defined unique landscape which 
is characterized by its transitional position between the southern slope and 
r de- 
3cussed 
earth 
luring 
the central part of the Alps, leading to frequent and .drastic changes in the 
local weather conditions. 
The Department of Geography, University of Zürich, and the Swiss 
Institute for Meteorology have installed an extensive ground measuring 
system, which should be extended further and used as a longterm observation 
es in 
network. 
thematic 
Both test sites were covered continuously with b&w aerial photography 
(Fig. 4a) of different scales and at different seasons. Additional color, 
IR-color and IR-scanner surveys (Fig. 2) were flown. 
the data, 
for its 
2. METHODS 
2.1. Mapping and inventories 
n toward 
a well 
f-shrubs, 
Some 
bottom 
ine 
In the first step detailed mapping and inventories of as many single 
features as possible in its seasonal aspects and changes are necessary. The 
examined thematic groups are the following: 
- climatic features: wind, temperature, precipitation, solar 
radiation, 
- surface features: land-use, vegetation, snow, hydrology, landforms, 
altitude, exposure, gradient of slopes, 
- subsurface features: geology, soils, soil moisture,