P. K. Haff

Earth Surface Processes Research

Contact P. K. Haff for graduate student opportunities in the area of Earth Surface Processes, including Neogeomorphology

Areas of interest:

Neogeomorphology: The surface of the earth is undergoing profound changes due to human impact. By some measures the level of human impact is comparable to the effects of major classical geomorphic processes such as fluvial sediment transport. Human-driven landscape change is occurring rapidly, and it affects the public directly. Anthropic landscape change has no geologic precedent and may represent an irreversible transition to a new and novel landscape with which we have no experience. For these reasons prediction of future landscape trajectories will be of increasing importance. The remarkable circumstance of being alive at, and cognizant of, the opening of a new geologic epoch – the Anthropocene – offers unique opportunities to the geomorphology community. These opportunities include exposure to new and challenging intellectual problems, the exciting prospect that geomorphology can contribute centrally to the debate over the likely future of the earth’s surface, an increased level of public visibility, influence and support, and a chance to attract a larger number of the best students to an expanded geomorphology. Beyond a consideration of the physical landscape response to a given human impact, the new geomorphology must anticipate what form that impact might take. This branch of geomorphology is called here neogeomorphology. Neogeomorphology operates partly on the basis of knowledge of the physical forces that drive landscape change, as studied in classical geomorphology and geology, but also incorporates elements of economics and other social sciences that help define the larger context that conditions the role of the physical forces. The combination of physical and social forces that drive landscape change represents the Anthropic Force. Neogeomorphology is the study of the Anthropic Force and its present and likely future effects on the landscape. Unique properties associated with the Anthropic Force include consciousness, intention and anticipation. These properties support the occurrence of entirely novel geomorphic phenomena, such as landscape engineering and management, i.e., intentional influences on the evolution of the earth’s surface. The occurrence of short time-scale phenomena induced by anthropic landscape change, the direct effects of this change on society, and the ability to anticipate and intentionally influence the future trajectory of the global landscape, combine to underscore the importance of prediction in neogeomorphology. FOR DRAFT OF A PAPER ON NEOGEOMORPHOLGY click here (PDF version). If PDF doesn’t download correctly, click here for HTML version.

Limitations on prediction in the geological and other sciences: Sources of uncertainty or error that arise in attempting to scale-up the results of laboratory-scale sediment transport studies for predictive modeling of geomorphic systems include: (i) model imperfection, (ii) omission of important processes, (iii) lack of knowledge of initial conditions, (iv) sensitivity to initial conditions, (v) unresolved heterogeneity, (vi) occurrence of external forcing, and (vii) inapplicability of the factor of safety concept. Sources of uncertainty that are unimportant or that can be controlled at small scales and over short times become important in large-scale applications and over long time scales. Control and repeatability, hallmarks of laboratory-scale experiments, are usually lacking at the large scales characteristic of geomorphology. Heterogeneity is an important concomitant of size, and tends to make large systems unique. Uniqueness implies that prediction cannot be based upon first-principles quantitative modeling alone, but must be a function of system history as well. Periodic data collection, feedback, and model updating are essential where site-specific prediction is required. In large geomorphic systems, the construction of successful predictive models is likely to be based upon discovery of emergent variables and a corresponding dynamics, rather than upon scaling-up the results of well-controlled laboratory-scale studies.

Landscape Modeling: Waterbots are elements of a landscape evolution model based on discrete units of runoff that are able to pick up and deposit sediment. The waterbot model is a cellular automaton model that captures much of the essence of more detailed hydrologic models. Waterbots are similar to the precipitons introduced by Chase in his discrete model of runoff erosion. In the precipiton model, individual precipitons were viewed as mimicking the effects of single storms. The term waterbot is used to avoid a suggestion that a discrete waterbot “particle” necessarily represents the result of a particular precipitation event. Instead a waterbot represents an abstract unit of runoff that can reflect the result of either many storms, or of a single storm. Waterbots represent one of potentially several species of geobots, or geologic agents, that might be deployed on a digital landscape to handle a range of geomorphic chores. FOR A DRAFT OF A PAPER ON EROSION AND DEPOSITION PROCESSES IN THE BLACK MOUNTAINS, Death Valley, California, as simulated by the waterbot model, click here (PDF version). If PDF doesn’t download correctly, click here for HTML version.

Recent Abstracts