Climate Change Impact on Water Resources in Northern Chile
Résumé
Northern Chile is characterized by desert-like climate. Five regions are recognized based on
their geomorphological features which are grouped into four areas, these are the Coastal
Plain and Range (Area I), the Central Depression (Area II), the Precordillera (Area III) and The
Western Range (Area IV+ including the Altiplano). Streams are very restricted in the
Tarapacá region, distributed mostly in the Altiplano and Precordillera where they flow
downwards through narrow ravines (“quebradas”) until infiltrating when reaching the
Central Depression, which concentrates the majority of groundwater resources. The study
aims to understand how climate change affects water resources by calculating Extreme
Climate Indices (ECI). The methodology encompasses the use of precipitation and
temperature data from 75 meteorological stations from the XV, I and II regions in Northern
Chile, as some neighboring stations in Bolivia and Northern Argentina in the monitored
period 1983 to 2012. ECI calculations were carried out using RClimdex script in the R
software. Variations in ECI are stronger in Area II. In this area maximum daily temperature
tends to increase whereas the minimum decreases producing an augmentation in
temperature daily oscillation. Evaporation is already very high in the Central Depression and
this temperature rise may trigger an increased rate in evaporated water during aquifer
recharge. Likewise this may also produce an increased rate in Prosopis Tamarugo (broadly
present) transpiration causing higher aquifer discharge. Consequently the water budget in
Central Depression aquifers may be reduced. Effects in other areas can also be observed- in
Area I the opposite effect to Area II occurs generating the increase of stratocumulus clouds
and augmenting fog availability something that coastal communities may take advantage of.
In Precordillera the flush-flooding likelihood is bigger as evidenced by an increase in the
R10mm index. Although there are 27 extreme climate indexes, only a few of them showed
clear trends in the monitored period but evidencing important effects on water resources,
especially in the most important aquifers in the Tarapacá region of Northern Chile.