Department of Geography

Wednesday Workshop Series
Speaker: TBD
Topic: TBD

Jose Constantine
Department of Geosciences
Williams College

Tropical Insights into Meandering Rivers: From the Self-Deforming Rivers of the Amazon to the Frozen Rivers of Borneo

Meandering rivers abound the globe and have fascinated artists and scientists for centuries. Recent decades of research led to important progress in our ability to explain why straightened rivers end up returning back to their meandering selves. But much of this research was focused on how the individual forms of meanders could force water to dig out the sides of river channels. Although it is true that the curved form of meanders drive an erosive behavour in river flow, recent observations from across tropical river systems have revealed new insights into the ways that meandering rivers can evolve. The meandering rivers of the Amazon Basin provide perhaps the last opportunity to study undisturbed river systems, with satellite imagery revealing an important role of sand grains. Sediment eroded from the Andean Mountains ends up moving through and eventually depositing within many of the rivers draining the Amazon. These sediment deposits end up deforming the riverbeds of meanders, helping to drive the erosive potential of river flow. The paradox is that the more Andean sediment supplied to these rivers, the more sediment they end up excavating from their valley floors. On the other side of the globe, the meandering rivers of Borneo could not be more different in terms of their behavour. Although they looks incredibly similar to their Amazonian counterparts, Bornean rivers appear frozen in place, with some of the lowest migration rates reported in scientific literature. Their valley floors are empty of features we expect to see in meandering rivers, and their response to widespread deforestation has been surprising. Palm oil plantations are replacing ancient tropical forest at rates that are unrivaled, but Bornean rivers have only gradually responded. Migration rates have increased somewhat, and there is some evidence that the mechanisms driving riverbank erosion have changed. However, there is no doubt that the response of Bornean rivers has been muted. This talk will summarize these new research findings, placing them in context with our ever evolving theory explaining the origin and evolution of the most dynamic of riverscapes.

Wednesday Workshop Series
Speaker: TBD
Topic: TBD

Spatial Risk Estimation for Individualized Auto Premiums based on Geographic Information System

Dipak K. Dey
Department of Statistics
University of Connecticut

This presentation is based on analyzing big auto insurance claim data to improve spatial risk estimation and classification. We explore a spatial variant of the double generalized linear model (DGLM), in which Tweedie distribution, as a special case, is used to model the pure premium, and the spatial correlation is incorporated via graph Laplacian regularization. The estimated spatial effects are then used to generate risk rankings at the county/zip code level. Simulation results and real data analysis showcase the efficacy of the new methods. Besides our recent progress, the challenges we face in large-scale predictive modeling and our future directions will also be discussed. In particular, we focus on collision data and build models for each state in US separately.

Wednesday Workshop Series
Speaker: TBD
Topic: TBD