Water Across the Critical Zone: Scaling from Local to Global Hydrology

2014 CUAHSI Biennial Colloquia

Ying Fan Reinfelder / Rutgers University

Eagleson Lecture

Background: The Eagleson Lecture is named after Peter S. Eagleson, a scientist who integrated ecology and hydrology and redefined hydrology from an ad hoc engineering speciality to a multidisciplinary, global environmental geoscience, in which the green, living features of the ecosystems have an important part to play. He has been seeking to develop new models of dynamic hydrology, looking at the hydrological cycle as the key process linking the physics, biology and chemistry of the Earth system.

Talk Description:

Although we have an intuitive understanding of what groundwater does in the critical zone at the scales of a column (atmosphere-plant-soil-bedrock), along a topo-sequence (ridge to valley), and across a small watershed (e.g., ~ 3rd order streams and floodplains), this talk examines how relevant groundwater is to river-basin, continent and global-scale patterns and processes. Through global observation syntheses, conceptual and numerical models, this talk suggests that groundwater influence is far more globally prevalent than previously thought, it forms an environmental gradient not fully captured by climate, and it profoundly shapes the critical zone at continental to planetary scales. Four examples illustrate these ideas: (1) global distribution of wetlands, gallery forests and desert oases as ecological refugia, (2) dry-season evapotranspiration in the Amazon, (3) patterns in plant rooting depth from topo-sequence to global scales, and (4) continental weathering and planetary change. More importantly, these examples reveal critical disciplinary, scale and data gaps that prevent us from translating what we learn at CZO scales to what we attempt to predict at the planetary scale.