APPLICATION OF STABLE ISOTOPES TOEVALUATE GROUNDWATER RECHARGE OF ACOASTAL AQUIFER IN NORTH-CENTRAL CHILEAND ITS ROLE IN VEGETATION DYNAMICS

摘要

The understanding of the water sources for plant growth is one of the key elementsto evaluate the present and long term primary productivity in arid ecosystems. We usestable isotope tools to evaluate the recharge mechanisms in a coastal aquifer locatedin the arid zone of north-central Chile. The main water sources in the study area, fog,rain and groundwater, were isotopically characterized over a decade. The isotope dataconfirmed that fog does not play any role in groundwater recharge. The water tableand isotope data showed that during low water conditions (dry periods), the aquifer ismaintained primarily by water recharged in the higher part of the Romeral basin. Duringhigh water table conditions (wet periods), recharge associated with local precipitationbecomes a significant source of groundwater recharge. The aquifer responded very fastto rains with amounts over the average level for precipitation (like El Ni?o conditions),