THE ROLE OF SPATIAL RESOLUTION AND CONTOUR INTERVAL IN DRUMLIN DELINEATION AND MEASUREMENT

Although drumlins are well studied and provide valuable insight into subglacial processes, the method in which drumlins are identified and measured is frequently subjective, inconsistent, and time consuming. Therefore, the purpose of this research was threefold: (1) to test the influence spatial resolution and contour interval have on calculations of drumlin morphometry in Central New York, (2) to determine if there is an optimum resolution and contour interval in which drumlin studies should be conducted, and (3) to design a relatively objective GIS technique to conduct drumlin morphometry studies. This was accomplished by generating a 1m Digital Elevation Model (DEM) and then generating subsequent resolutions of 3m, 5m, 10m, 30m, and 80m. Each DEM was then contoured using intervals of 2m, 3m, 4m, 5m, 8m, 10m, and 12m. All drumlins were identified and extracted by means of the lowest enclosed contour line. The spatial characteristics (i.e. area, elongation, orientation) of each drumlin were calculated and compared to establish optimum resolutions and contour intervals. Coarse resolutions (i.e. 80m, 30m) cause significant changes in measurements, opposed to fine resolutions (i.e. 10m, 5m, 3m, 1m) which have relatively negligible differences. As a result, a 10m DEM is the coarsest resolution in which there is a minimal loss of detail and is therefore considered to be the optimum resolution to conduct a drumlin morphometry study in this drumlin field. As a result, it is recommended that an optimum spatial and vertical resolution is determined before conducting morphometric studies of landforms. The GIS technique used in this study can be applied to other drumlin fields, which would provide a standardized method for drumlin analyses, and can potentially be used to analyze the morphology of other glacial features (i.e. cirque, flutes, moraines).