H23F-1631
Using integrated models to diagnose scaling of hydrologic processes to the continent.
Tuesday, 15 December 2015
Poster Hall (Moscone South)
Reed M Maxwell1, Laura E Condon1,2, Stefan J Kollet3,4, Katharine Maher5, Roy Haggerty6 and Mary Michael Forrester1, (1)Colorado School of Mines, Hydrologic Science and Engineering Program and Department of Geology and Geological Engineering, Golden, CO, United States, (2)Syracuse University, Civil and Environmental Engineering, Syracuse, NY, United States, (3)Forschungszentrum Jülich, Agrosphere (IBG 3), Jülich, Germany, (4)Centre for High-Performance Scientific Computing in Terrestrial System, ABC/J Geoverbund, Jülich, Germany, (5)Stanford University, Geological and Environmental Sciences, Stanford, CA, United States, (6)Oregon State University, College of Earth, Ocean and Atmospheric Sciences, Corvallis, OR, United States
Abstract:
The terrestrial hydrologic cycle (groundwater, overland flow, land surface and vegetation) is a complex, coupled system with processes spanning a wide range of scales. Surface and subsurface flow dynamics govern residence time or water age, which is a key metric of flow, storage and water availability for human use and ecosystem function. However, open questions remain regarding the timing and distribution of these flowpaths, and how they interact with geology and hydrologic variables such as recharge at large scales. Although observations in small catchments have shown a fractal distribution of ages, residence times are difficult to directly quantify or measure in large basins. Here, we present the results of flow and transport simulations of major watersheds across North America. These results are used to compute distributions of water ages. The watersheds evaluated have peak ages from 1.5 – 10.5 years, in agreement with ages from isotopic observations using bomb-derived radioisotopes. The peak age is controlled by the mean hydraulic conductivity, which is a function of the prevailing geology. All river basins are also characterized by a wide range of residence times—from 0.1 to 10,000 years. The shape of the residence time distribution depends on aridity, which in turn determines water table depth and the frequency of shorter flowpaths. Finally, we present a path forward where computational hydrology can be used, in conjunction with observations and theory, to understand scaling relationships.
