Continental-scale Isotope Hydrology

Abstract:

Studies that explore isotope hydrology at global scales are rare. This collaborative research uses isotopic data to track water as it flushes through shallow, critical zone systems, and also through deeper, groundwater flow systems. This presentation focuses on tropical regions which, by 2050, will host half of the world’s population. Some of the key findings are: 1) that plant transpiration water supplies may be disconnected from groundwater recharge and streamflow in many tropical settings, 2) that a substantial fraction of tropical river flows are replenished by rainfall that reaches the river in less than ~2 months, 3) that more frequent intensive rainstorms brought about by global climate warming may augment groundwater renewal across the tropics, 4) that even though groundwater comprises ~99% of fresh water stored in the tropics, only a small fraction of this resource is refilled during one human lifespan. These pan-continent studies juxtapose extratropical and tropical isotope hydrology in an effort to demonstrate some of the divergent considerations and isotope-based-approaches relevant to low-latitudes ecohydrology.