| As part of the study on the Mantaro river basin's (central Andes of
Perú) current vulnerability to climate change, the temporal and spatial
characteristics of frosts were analysed. These characteristics included
intensity, frequency, duration, frost-free periods, area distribution and
historical trends. Maps of frost risk were determined for the entire river
basin, by means of mathematical algorithms and GIS (Geographic Information
Systems) tools, using minimum temperature – 1960 to 2002 period,
geomorphology, slope, land-use, types of soils, vegetation and life zones,
emphasizing the rainy season (September to April), when the impacts of frost
on agriculture are most severe. We recognized four categories of frost
risks: low, moderate, high and critical. The critical risks (with a very
high probability of occurrence) were related to high altitudes on the basin
(altitudes higher than 3800 m a.s.l.), while the low (or null) probability of
occurring risks were found in the lower zones (less than 2500 m a.s.l.). Because
of the very intense agricultural activity and the high sensitivity of the
main crops (Maize, potato, artichoke) in the Mantaro valley (altitudes
between 3100 and 3300 m a.s.l.), moderate to high frost risks can be expected,
with a low to moderate probability of occurrence. Another significant result
was a positive trend of 8 days per decade in the number of frost days during
the rainy season. |