Isotopic composition in precipitation and groundwater in the northern mountainous region of the Central Valley of Costa Rica

Abstract

The linkage between precipitation and recharge is still poorly understood in the Central America region. This study focuses on stable isotopic composition in precipitation and groundwater in the northern mountainous region of the Central Valley of Costa Rica. During the dry season, rainfall samples corresponded to enriched events with high deuterium excess. By mid-May, the Intertropical Convergence Zone poses over Costa Rica resulting in a depletion of O/O and H/H ratios. A parsimonious four-variable regression model (r= 0.52) was able to predict daily δO in precipitation. Air mass back trajectories indicated a combination of Caribbean Sea and Pacific Ocean sources, which is clearly depicted in groundwater isoscape. Aquifers relying on Pacific-originated recharge exhibited a more depleted pattern, whereas recharge areas relying on Caribbean parental moisture showed an enrichment trend. These results can be used to enhance modelling efforts in Central America where scarcity of long-term data limits water resources management plans.

Isotope hydrology of a tropical coffee agroforestry watershed: Seasonal and event‐based analyses

“…Others also determined that enhanced moisture recycling processes, including strong localized convective events due to evapotranspiration fluxes, resulted in high LMWL intercepts and slopes, whereby d ‐excess increased as a result (Froehlich et al, ; Gat & Matsui, ). Therefore, the increases in the d ‐excess value that we observed during the dry and transitional seasons are likely indicative of increased continental moisture recycling (Froehlich et al, ; Gat, Bowser, & Kendall, ; Sánchez‐Murillo et al, ). The average d ‐excess value (+15.0‰) we observed confirms that moisture recycling is an important component of the local hydrology in this region.…”

Moisture transport and seasonal variations in the stable isotopic composition of rainfall in Central American and Andean Páramo during El Niño conditions (2015–2016)

“…For these relations, the corresponding isotopic composition variations with rainfall amount showed a decrease of 3.1‰ per 100 mm at Chirripó and 5.9‰ per 100 mm at Cajas, respectively. In general, these isotopic rates are consistent with those reported by Sánchez‐Murillo et al () for the intermountainous region of Costa Rica (2.8‰ per 100 mm, highest elevation ~3,400 m asl) and by Gonfiantini et al () for Bolivia (6.6‰ per 100 mm, Yungas–Altiplano, highest elevation ~5,200 m asl).…”

“…These observations show that water vapour transported from this moisture source was likely subjected to moisture recycling when the air masses travelled across the Caribbean slope of Costa Rica during this period. This effect was also reported by Rhodes et al () and Sánchez‐Murillo et al (, ) in Monteverde (Pacific domain) and the Central Valley of Costa Rica, respectively. Rainfall originating from the less frequent precipitation source, the Pacific Ocean, was also linked with d ‐excess values around +10‰.…”

DOC Transport and Export in a Dynamic Tropical Catchment

“…This study was conducted at the Wildlife Refuge Cerro Dantas located within the Braulio Carrillo National Park, on the Caribbean slope of central Costa Rica (Figure a). Cerro Dantas is part of the Barva volcano edifice, and the parental material is primordially basaltic and andesitic volcanic rocks (Figure b; Sánchez‐Murillo et al, ). Quebrada Grande is a small (2.6 km 2 ) and mixed primary and secondary forested catchment with minimum anthropogenic activity in the last 100 years.…”