You Want Me to Predict What?

Geomorphic models have a wide range of capabilities in terms of prediction, and this range is part of the reason for this volume. Haff [1996] pointed out that landscape-scale geomorphic models are fundamentally ill-suited to precise prediction and that reductionism is ill-suited to landscapescale problems. Geomorphic models run the gamut of spatial and temporal scales and modeling approaches, from linked sediment transport and computational fluid dynamics reductionist models applied to one or two meander bends [Nelson and Smith, 1989] to more rules-based landscape evolution models applied to entire orogens [Tucker and Slingerland, 1996]. Some problems involve a limited range of processes and scales and, thus, allow more straightforward simulation and precise prediction [Iverson, 2000; Denlinger and Iverson, 2001]. Landscape-scale geomorphic models, conversely, cannot in general give precise predictions. With faster computers, better models, and improved visualization techniques that include realistic, color, 3D, and/or animated graphics, modelers may become overenthusiastic about what they can predict. These enthusiasms may be picked up by or sold to managers, who have many reasons for wanting to know the future. In responding to pressures for answers, managers can imagine real-world uses for the realism they see depicted in such graphics, make connections that are not reasonable, and come to expect predictions of the unpredictable. If modelers are not careful they run the risk of making promises that cannot be fulfilled. Only later, as the enormity of certain promises made sinks in, does the modeler say in exasperation, “You want me to predict what?” Depending on the answer, the modeler may then be placed in the position of either dancing rapidly to meet expectations or backpedaling to dispel them. As society becomes more interested in geomorphic problems, or as geomorphologists become more interested in societally relevant issues, the geomorphologist faces a risky opportunity. Beyond the opportunity to do research, societally relevant issues offer geomorphologists a certain satisfaction that is rarely found in, e.g., investigations of charmanticharm asymmetries in high energy photoproduction Prediction in Geomorphology Geophysical Monograph 135 Copyright 2003 by the American Geophysical Union 10.1029/135GM04 You Want Me to Predict What?