Tracer hydrology of the data‐scarce and heterogeneous Central American Isthmus

Abstract

Numerous socio-economic activities depend on the seasonal rainfall and groundwater recharge cycle across the Central American Isthmus. Population growth and unregulated land use changes resulted in extensive surface water pollution and a large dependency on groundwater resources. This work combines stable isotope variations in rainfall, surface water, and groundwater of Costa Rica, Nicaragua, El Salvador, and Honduras to develop a regionalized rainfall isoscape, isotopic lapse rates, spatial-temporal isotopic variations, and air mass back trajectories determining potential mean recharge elevations, moisture circulation patterns, and surface watergroundwater interactions. Intra-seasonal rainfall modes resulted in two isotopically depleted incursions (W-shaped isotopic pattern) during the wet season and two enriched pulses during the mid-summer drought and the months of the strongest trade winds. Notable isotopic sub-cloud fractionation and near-surface secondary evaporation were identified as common denominators within the Central American Dry Corridor. Groundwater and surface water isotope ratios depicted the strong

Aplicación de Isótopos estables e hidroquímica para la comprensión del sistema hidrológico en Laguna de Tiscapa. Managua, Nicaragua

“…Por otra parte, la composición isotópica en Tiscapa se encuentra más cerca a la composición del agua subterránea (medio -6.88 ‰ en δ 18 O). En Figura 2, se indica la existencia de pozos con una composición isotópicamente más enriquecidos, estos se ubican en zona entre Laguna de Tiscapa y Lago Xolotlán, lo cual se puede atribuir a que la extracción de agua en los pozos han provocado conos de abatimiento, en la Figura 1.B, se puede observar que los puntos muestreados próximos a laguna en zona oeste presenta composición media de -6.7‰ en δ 18 O y los ubicados en zona noreste composición media de -5.6 ‰ en δ 18 O, lo que sugiere una probable interacción de Laguna de Tiscapa con el agua subterránea, ocasionando que el agua subterránea se esté enriqueciendo isotópicamente hasta -1.1 ‰ en δ 18 O, de forma similar Sánchez (Sánchez-Murillo, et al, 2020) ha reportado que la alta conectividad entre lagos y agua subterránea en Nicaragua, producen enriquecimiento del agua subterránea aproximadamente en -1.74 ‰ en δ 18 O.…”

Chirripó Hydrological Research Site: advancing stable isotope hydrology in the Central American Páramo

“…CHRS data are also key to identify inputs from the central Pacific Ocean and local evapotranspiration fluxes. Overall, as water vapour encounters the main mountain range, orographic distillation and convergence increase, resulting in depleted precipitation arriving from the Pacific domain (Fig 2b;Sanchez-Murillo et al, 2020a). The lesser contribution of recycled water vapour arriving at CHRS is indicated by thed -excess variations in precipitation (d-excess values>10 The first isotopic characterization of the surface water system of CHRS indicate that the evaporation conditions in the glacial lakes are highly influenced by input from precipitation that is in isotopic equilibrium with local water vapour, yielding low evaporation to inflow ratios (< 20%, Esquivel-Hernandez et al, 2018).…”

Tracing Water Sources and Fluxes in a Dynamic Tropical Environment: From Observations to Modeling

“…Similar factors affecting leeward/windward isotopic lapse rates have been recognized in other tropical regions (Gonfiantini et al, 2001). The large sensibility of dδ/dz gradients to local circulation features, coupled with the strong seasonal and interannual bias, emphasizes the need for robust and long-term stations (>4 years; Putman et al, 2019), in particular when δ-elevation rates are used to derive critical water management information, such as mean recharge elevations (MREs), either from simple regression analysis or Bayesian methods (Yamanaka and Yamada, 2017;Sánchez-Murillo et al, 2020).…”

“…A P/GW ∼ 1 indicates a rapid recharge via preferential flow paths. Caribbean and Pacific isotopic lapse rates were used to calculate potential mean recharge elevations (MRE in m asl) under the assumption that groundwater isotope ratios under baseflow conditions are representative of mean annual recharge conditions (Yamanaka and Yamada, 2017;Sánchez-Murillo et al, 2020). Isoscapes show a remarkable spatial variability of δ 18 O, with an enriched composition over coastal areas as a result of rainfall forming at lower altitudes and a low-level convergence favored by higher temperatures.…”

“…(ii) Spring water, surface water and groundwater (both timeseries and seasonal spatial snapshots), hydrothermal fluids, and soil water (Sánchez-Murillo et al, 2014, Sánchez-Murillo et al, 2017a, Sánchez-Murillo et al,2019bCorrales-Salazar et al, 2016;Ramírez-Leiva, et al, 2017;Salas-Navarro et al, 2019). (iii) Useful isotope-informed applications and estimations, such as stratiform and convective rainfall separation, high resolution isoscapes, recharge mechanisms and elevations, and contribution of magmatic fluids; and tracer-aided rainfall-runoff modeling to estimate flow pathways, runoff generation processes and water ages Birkel and Soulsby, 2016;Dehaspe et al, 2018;Sánchez-Murillo et al, 2020).…”