How I stopped worrying and learned to love contingency (J.D. Phillips, 2017)

Here it is! In one place! The collected unpublished musings of Professor Jonathan Phillips on all things geomorphic from May 2014 to August 2017, entitled The Perfect Planet. This document presents a collection of Professor Phillips blog posts, organized by theme.

In addition to reading through this collection of posts, people interested in disruptive ideas about geomorphology will also want to keep and eye on JDPs blog. We are working on getting JDP to post something here on xriver.net, too.

Professor Phillips from the Department of Geography at the University of Kentucky has been thinking long and hard about the place of equilibrium in geomorphology, as well as the importance of contingency. Several of his papers have been particularly important to me as I have developed my ideas about geomorphic systems and how to think about them.

With our current project of re-imagining the paradigm for studying geomorphology in mind, I was particularly taken with JDP’s most recent posts entitled HOW I STOPPED WORRYING AND LEARNED TO LOVE CONTINGENCY (part 1, part 2, part 3, part 4,¬† and part 5). They are well worth the time to read.

Adapting regime theory to a stochastic world

The concept of river regime is about as close to an equilibrium concept as you can get. Fundamentally, there are some problems that cannot be tackled using a regime-based paradigm, but there are some circumstances where such an approach can be quite useful, particularly for managers and consulting geoscientists who need easy-to-use tools with modest data requirements to answer extremely complex management questions with important socioeconomic consequences.

In our paper, Rob Millar and I have reviewed the basis for regime theory, and have developed a Monte Carlo simulation tool (available in the standalone UBCRM software package) that at least incorporates uncertainty, even if it does not truly recognize the stochastic nature of stream channel dynamics.  In the last section of the paper, we go to some length to articulate what we think are the limitations of a regime-based approach to river dynamics.

A stochastic model of wood recruitment and jam formation to evaluate forest disturbance effects

In this recent paper, Sarah Davidson links disturbances to the riparian forest to changes in fish habitat associated with instream large wood. The paper presents an analysis of the effects of forest fire regime, and considers various riparian logging scenarios. The focus of the analysis is to situate the mean response of the stream channel within the context of the range of channel conditions. The model uses a Monte Carlo modelling approach, applied to a conceptually simple model of channel and jam dynamics.

This kind of modelling approach is particularly useful when evaluating the particular response trajectories of a stream following disturbance, since it emphasizes the range of conditions, not simply the mean condition. The ideas presented in this paper (and a yet-to-be-published chapter from Sarah’s thesis on the Stochastic Channel Simulator, STOCASIM) have strongly influenced my thinking about the value of equilibrium concepts in fluvial geomorphology.

unreasonable expectations

IMG_1010.JPGOne of the main problems with how we as a community have approached the study of river dynamics is that we have created unreasonable expectations for those that are charged with managing rivers. For example, we describe thresholds for channel scour and migration, but fail to mention that the thresholds are fuzzy, and that rivers are unpredictable, chaotic systems. When we make a a prediction that channel change should occur for a flood of magnitude X, and then nothing much happens during such an event, we look foolish and the managers  lose confidence in the underlying science.

Continue reading “unreasonable expectations”