5. CONCLUSIONS
In this work, we developed a description of the atmospheric moisture
sources that define rain over the Caribbean and Andean subregions in
Colombia. This contribution integrates relevant information from the
isotopic composition of precipitation with results from the mathematical
modeling FLEXPART to better describe the structure of the regional
moisture sources and the relative contribution in terms of amount and
ecological relevance. This approach refines the strategy of moisture
accounting by considering the optimal transport day instead of the
canonical 10-day mean lifetime of water vapor in the atmosphere,
avoiding, as much as possible (under)overestimations in the moisture
contributions. In this sense, our calculations are more realistic and
robust.
The differentiation between regions in the country allowed us to
identify a variation in the amount and seasonality of moisture
contribution from different sources. Our results indicate a
predominance of terrestrial moisture sources (56% and 59% annual mean
contributions for the Caribbean and Andes regions, respectively),
followed by oceanic moisture sources, dominated by the contribution from
the Pacific in the Andean Region (26% contribution) and the Atlantic in
the Caribbean region (28%).
The quantification of moisture sources in each region reveals that
precipitation regimes depend on the seasonality of the regional
composition of moisture sources and the diverse underlying mechanisms,
and the physical variables related to each zone, including variables
such as topography, geographic location, and environmental features. The
isotopic analysis results reveal that the processes which give origin to
precipitation in the Andean region are linked to the advance of moisture
flow into the continent, and are related to orographic ascent, as can be
seen in the LMWLs. For the Caribbean region, the closeness factor to the
main sources such as the Caribbean Sea and the Atlantic Ocean has a high
influence on the precipitation regime. However, an important influence
from the Pacific Ocean is also evident for this region.
The teleconnections between the sources and targets clarify that water
resources management should consider not only surface hydrology, but
also the links that directly influence the precipitation regime. The
dynamics of the climate system at the local level is conditioned by
phenomena that depend synergistically on other places, involving the
transfer of vital ecosystem services. In this work, in particular, we
found that the precipitation regime of the Colombian Andes is highly
conditioned by meteorological and ecological processes within the
region, as well as in neighboring Amazon and the Orinoco, such that
ecological alterations associated with deforestation or land use could
have impacts on the amount of moisture that is transported from these
regions, threatening water, energy and economic security in the region.