Silvia Piovan

How many Carolina bays? An analysis of Carolina bays from USGS topographic maps at different scales

ABSTRACT Carolina bays are elliptical or oval geomorphologic depressions often characterized by the presence of shallow ponds or swamps, that occur in the Atlantic Coastal Plain of the US from Delaware to Florida. Explanations of their origin include meteor impacts, subsidence from subsurface karst, and thermo karst or thaw lakes. Quantification of the number of Carolina bays, which may help in forming theoretical explanations for their origin, is also elusive ranging from 10,000 to 500,000. This research demonstrates the large variations in numbers of Carolina bays as a function of mapping scale, the most important factor in enumerating topographic features. The systematic skills from analysts and cartographers in the United States Geological Survey, who mapped Carolina bays on two different scale map series in the national mapping program were exploited. The results indicate the number of Carolina bays is 20 times greater, when enumerated at a 1:24,000 scale as compared to a 1:100,000 scale. An empirical model of the frequency of Carolina bays using different minimum mapping units, (MMUs) was developed and applied to estimate bay frequency at any MMU. A more reliable estimate of the number of Carolina bays in the US from Florida to Virginia using an MMU of 0.1 ha is between 40,000 and 50,000.

Application of Mobile Data Capture with Imagery Support

Remote sensing technology and mobile devices are two data collection approaches that are proving invaluable in the disaster response phase of the hazard event. The adoption of these approaches is not universal and still faces significant challenges. The user community must understand the technology, learn how to acquire it, and be trained on its use before the disaster event. Much has been written about volunteered, unvolunteered, and crowd-sourcing of geospatial information for disaster response and recovery. While research in these areas continues, most U.S. federal and state agencies rely on authoritative data collected by authorized personnel. This research focuses on the use of geospatial technology with mobile devices by appointed users—those individuals with authorization to collect geospatial information for a governmental agency with authority in the disaster response process. This chapter describes a project to develop a web-app that allows appointed users to collect geospatial data in the field with Google Maps and user-supplied imagery and with pre-defined and user-defined structured forms. Although the original purpose focused on disaster response and recovery activities, such as the Urban Search and Rescue (USaR) house-to-house searches, the user-groups, purposes, and technologies rapidly changed in this two year project. Technology for the web environment rapidly changes, particularly for mobile devices. Our focus on the USaR teams changed to all parishes in the state of Louisiana. This project used an agile software development approach, which permitted the evolving nature of the user requirements. Without this agile approach the user community would not have adopted the application for emergency response.