LCZO -- Stable Isotopes -- Stable Isotope (δ18O and δ2H) Data -- Puerto Rico -- (1994-2013)

OVERVIEW

Description/Abstract

Like many mountainous areas in the tropics, watersheds in the Luquillo Mountains of eastern Puerto Rico have abundant rainfall and stream discharge and provide much of the water supply for the densely populated metropolitan areas nearby. Projected changes in regional temperature and atmospheric dynamics as a result of global warming suggest that water availability will be affected by changes in rainfall patterns. It is essential to understand the relative importance of different weather systems to water supply to determine how changes in rainfall patterns, interacting with geology and vegetation, will affect the water balance. To help determine the links between climate and water availability, stable isotope signatures of precipitation from different weather systems were established to identify those that are most important in maintaining streamflow and groundwater recharge. Precipitation stable isotope values in the Luquillo Mountains had a large range, from fog/cloud water with δ2H, δ18O values as high as +12 ‰, −0.73 ‰ to tropical storm rain with values as low as −127 ‰, −16.8 ‰. Temporal isotope values exhibit a reverse seasonality from those observed in higher latitude continental watersheds, with higher isotopic values in the winter and lower values in the summer. Despite the higher volume of convective and low-pressure system rainfall, stable isotope analyses indicated that under the current rainfall regime, frequent trade -wind orographic showers contribute much of the groundwater recharge and stream base flow. Analysis of rain events using 20 years of 15 -minute resolution data at a mountain station (643 m) showed an increasing trend in rainfall amount, in agreement with increased precipitable water in the atmosphere, but differing from climate model projections of drying in the region. The mean intensity of rain events also showed an increasing trend. The determination of recharge sources from stable isotope tracers indicates that water supply will be affected if regional atmospheric dynamics change trade- wind orographic rainfall patterns in the Caribbean.

For more data a USGS open file report is available: Stable Isotope (δ18O and δ2H) Data for Precipitation, Stream Water, and Groundwater in Puerto Rico http://dx.doi.org/10.3133/ofr20141101

Creator/Author

Martha A. Scholl|Angel Torres-Sanchez|Manuel Rosario-Torres

CZOs

Luquillo

Contact

Martha Scholl; mascholl@usgs.gov

Subtitle

Stable Isotope (δ18O and δ2H) Data for Precipitation, Stream Water, and Groundwater in Puerto Rico

SUBJECTS

Disciplines

Hydrology|Water Chemistry|Climatology / Meteorology

Topics

Stable Isotopes

Subtopic

Stable Isotope (δ18O and δ2H) Data

Keywords

Stable isotope|δ18O|δ2H|Precipitation|Stream Water|Groundwater|water balance|fog water|cloud water

Variables

δ18O|δ2H|precipitation

Variables ODM2

delta-18O of H2O|Deuterium|Precipitation

TEMPORAL

Date Start

1994-08-31

Date End

2013-03-26

SPATIAL

Field Areas

Northeastern Puerto Rico and the Luquillo Mountains|Rio Icacos|East Peak|Rio Mameyes

Location

Puerto Rico

North latitude

18.4119

South latitude

18.1707

West longitude

-65.8473

East longitude

-65.6751

REFERENCE

Citation

Scholl, M.A., Torres-Sanchez, A., and Rosario-Torres, M., 2014, Stable isotope (δ18O and δ2H) data for precipitation, stream water, and groundwater in Puerto Rico: U.S. Geological Survey Open-File Report 2014–1101, 29 p., http://dx.doi.org/10.3133/ofr20141101.

CZO ID

3850