Introducing the Case Study Areas: Hydro-climatic and Governance Contexts - Climate Change and Water Governance: Adaptive Capacity in Chile and Switzerland - page 104

important industry for the region. In the agricultural corridor of the interior valleys,
the export agribusiness is focused on avocados, cherimoyas and flowers. Recently,
drip feed irrigation has been applied to the hill sides, to cultivate otherwise dry and
unproductive land.

6.3.1 Climatic Detail

Again, a more detailed discussion of climate change impacts on the Aconcagua
basin will be discussed in Chap. 9 , but for now, I shall highlight some of the key
characteristics of the basin as detailed by Reyes Carbajal ( 2007 ). The total area of
the watershed (see Map 6.3 ) is 7,340 km 2 (45% of Valparaiso Region), which covers
a highly variable region where the Andes rise to more than 5,000 m.a.s.l. within
200 km of the coastline (Vicuña et al. 2011 ). Two climate types are observed in the
Aconcagua basin: warm Mediterranean and cold climate in the high Andes. Mean
annual temperature is 5.2 °C but in summer it increases above 27 °C. Mean annual
monthly precipitation at the coast is approximately 395 mm/year, in the central part
of the basin it is 261 mm/year, presenting dryer areas and less amount of precipita-
tion because of its relief. At higher elevations precipitation increases to 467 mm/
year. Basin-average annual runoff at the coast side is over 50 mm/year and in the
central part less than 20 mm/year. Higher values occur in summer and spring as a
result of glacier and snow melt, lower flows occur during autumn and winter espe-
cially in the upper part above 1,000 m altitude where the flow regime is nival. At
lower elevations the regime becomes mixed; nivo-pluvial.
In the Andes, glacial melt water supports river flow and water supply for tens of
millions of people during the long dry season, and precipitation can be close to zero
during summer (Pellicciotti et al. 2008 ). Hydrological impact studies have shown
that warming leads to changes in the seasonality of river flows in areas where a high
percentage of winter precipitation currently falls as snow (Kundzewicz et al. 2007 ) .
The IPCC (Kundzewicz et al. 2007 ) have shown that higher temperatures will gen-
erate increased glacier melt. Studies in the Aconcagua basin have suggested that the
increase in the melt water production from the glaciers in the upper section of the
Aconcagua basin have already taken place and that the glaciers are now in a phase
of diminishing contribution to the basin stream flow (Pellicciotti et al. 2007 ) .
Studies into temperature trend analysis have shown that in the Aconcagua region,
and specifically in the upper Aconcagua River Basin a statistically significant
increase in both summer and winter air temperature in the last decades has been
observed (Pellicciotti et al. 2008 ) . Carrasco et al. ( 2005 ) have observed an elevation
in the snow line in central Chile by 127 m in the last quarter of the twentieth century.
In another study by (Reyes Carbajal 2007 ), analysing hydro-climatic trends in the
basin, decreases in summer run off were observed mainly in the upper part of the
basin, as a result of a reduction in glacial coverage and snow depth in the drainage
watershed.