Rivers: Erroneous Perceptions and Faulty Predictions

Stanley A. Schumm
Department of Earth Resources, Colorado State University
Mussetter Engineering, Inc., Fort Collins, CO
stans@mussei.com

In spite of the tremendous advances in geomorphology during the last 50 years, frequently our perceptions can lead to faulty conclusions and predictions. Erroneous perceptions can be the result of training (What did your professor tell you?), of experience (Where have you been?), and of self-interest (What can be gained?).

Perceptions can be two kinds:

1. a perception of stability, that change is anomalous and that general relations (hydraulic geometry) are everywhere applicable (Ohio and Snake River, and Rocky Mountain streams), and
2. a perception of instability, that once change has commenced, it will continue and be a major long-term problem (cutoffs and degradation of Mississippi and Nile Rivers, southwestern USA arroyos and southeastern USA channelized streams.

The examples illustrate how to avoid mistakes by taking a broad, spatial, and temporal view of a problem.