Physics Seminar: Realizing the Promise of the Eagleson Report

Greetings,

The Physics seminar this week will meet on Friday, October 25 at 3:00 pm.  You can join live in 210 Fawcett Hall or online at this link: 

https://wright.webex.com/meet/sarah.tebbens
 

The talk will be by Dr. Allen Hunt (live) and is titled "Realizing the Promise of the Eagleson Report." 
 

We hope you can join us.

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Abstract

35 years ago, the Hydrology Community came together to propose a new way forward for hydrologic sciences. This process had two overarching goals: 1) to identify the greatest challenges in research and education in the hydrologic sciences, 2) to develop the infrastructure to promote the solution of these problems. The resulting publication by the National Academy of Sciences has been referred to as the Eagleson Report. In a particularly prescient portion of this report (pp. 65-66, which I recommend everyone read in advance), a template for solution of the central problem of hydrology, the water balance (i.e., the prediction of evapotranspiration ET as a function of climate variables) is laid out, including the observation that the same template would serve for the carbon cycle.

Three years ago, my colleagues and I came up independently with a solution of the water balance, published in Water Resources Research. Unwittingly, I had laid out the same solution as proposed 30 years before. Because limitations of water and energy were addressed separately in different climate regimes, even though the result for ET was continuous across this boundary, its derivative was not. In 2021, we characterized this predicted sudden change in slope as a defect. In 2023, however, we found that the resulting prediction for the precipitation elasticity of streamflow, which generated a double peak in the elasticity as a function of aridity index, was verified across four continental- to global-scale datasets. In keeping with the solution proposed of ecological optimality, we also determined that the predictions of net primary productivity and tree species richness as functions of climate variables exhibited unprecedented accuracy. In retrospect, we can also show what information that permitted the solution in 2021 was missing in 1991, namely the exact forms of the scaling relationships employed to predict soil formation and vegetation growth on which the optimality was based, possibly explaining why the problem remained unsolved for an additional 30 years.