Jacob Napieralski

Towards a GIS assessment of numerical ice-sheet model performance using geomorphological data

A major difficulty in assimilating geomorphological information with ice-sheet models is the lack of a consistent methodology to systematically compare model output and field data. As an initial step in establishing a quantitative comparison methodology, automated proximity and conformity analysis (APCA) and automated flow direction analysis (AFDA) have been developed to assess the level of correspondence between modelled ice extent and ice-marginal features such as end moraines, as well as between modelled basal flow directions and palaeo-flow direction indicators, such as glacial lineations. To illustrate the potential of such an approach, an ensemble suite of 40 numerical simulations of the Fennoscandian ice sheet were compared to end moraines of the Last Glacial Maximum and the Younger Dryas and to glacial lineations in northern Sweden using APCA and AFDA. Model experiments evaluated in this manner were ranked according to level of correspondence. Such an approach holds considerable promise for optimizing the parameter space and coherence of ice-flow models by automated, quantitative assessment of multiple ensemble experiments against a database of geological or glaciological evidence.

The application of control charts to determine the effect of grid cell size on landform morphometry

Geoscientists have become increasingly dependent on digital elevation models (DEMs) to delineate and measure landforms and landscapes. However, the DEM grid cell size available may not be the optimum resolution; this can mask subtle changes in measurements and lead to erroneous results. This paper presents a standardized statistical technique (i.e. statistical process control charts (SPCC)) for determining the optimum DEM resolution (i.e. the coarsest resolution in which detail is not sacrificed) for landforms (e.g. drumlins). For this study, forty-four DEM resolutions, ranging from 1 to 80 m, were used to assess the effect of resolution on drumlin size, shape, and centroid. The results indicate that the optimum resolution for the size variables (width and length) was coarser than the optimum resolution for shape indices (elongation and rose curve). Drumlin location tends to drift in a predictable direction and rate as grid cell size coarsens above particular thresholds. The results prove that resolution plays a critical role in correctly evaluating drumlin morphometry and that care must be taken when utilizing DEMs to summarize drumlin characteristics. The creation of a standardized technique to describe drumlins will allow for scrutiny of previous work and straightforward comparative analyses between studies, while utilizing the optimum resolution will help decipher landform patterns, reveal relationships, and provide more insight into landform evolution.

Urban Stream Deserts as a Consequence of Excess Stream Burial in Urban Watersheds

The Rouge River watershed, a highly urbanized watershed in southeast Michigan, has substantial impervious surface coverage, relatively high population density, and modified stream network (e.g., stream straightening and burial, dams, and underground retention). The number of stream channels and order decreases, increasing flooding, reducing water quality, and decreasing aquatic species. This study defines, identifies, and describes the progression of the geographic pattern of urban stream deserts—defined as those areas within a watershed that exhibit no surface stream channels due to the effects of human development and population growth. Urban stream deserts are identified and characterized using three data sets: (1) historical aerial imagery, (2) historical census boundary and tables, and (3) stream network data. Flowlines digitized off aerial photos from 1949 are compared against 2013 flowlines to identify areas of the watershed now devoid of stream channels. In the Rouge River watershed, stream density has decreased since 1949, which coincides with a rapid population increase and systematic burial of urban streams. Urban stream deserts in the Rouge River watershed constitute 23 percent of the watershed area, but these areas included as much as 66 percent of the watershed population in 1950 (as the urban stream deserts were developing) and dropped to 41 percent in 2010. This conceptual model of urban stream deserts is applicable to many urban and industrialized areas that have replaced stream channels with infrastructure during periods of economic growth, only to experience depopulation, aging infrastructure, and, as a result, degraded, modified, or altogether buried stream networks.

Comparing predicted and observed spatial boundaries of geologic phenomena: Automated Proximity and Conformity Analysis applied to ice sheet reconstructions

Comparing predicted with observed geologic data is a central element of many aspects of research in the geosciences, e.g., comparing numerical ice sheet models with geomorphic data to test ice sheet model parameters and accuracy. However, the ability to verify predictions using empirical data has been limited by the lack of objective techniques that provide systematic comparison and statistical assessment of the goodness of correspondence between predictions of spatial and temporal patterns of geologic phenomena and the field evidence. Much of this problem arises from the inability to quantify the level of agreement between straight or curvilinear features, such as between the modeled extent of some geologic phenomenon and the field evidence for the extent of the phenomenon. Automated Proximity and Conformity Analysis (APCA) addresses this challenge using a system of Geographic Information System-based buffering that determines the general proximity and parallel conformity between linear features. APCA results indicate which modeled output fits empirical data, based on the distance and angle between features. As a result, various model outputs can be sorted according to overall level of agreement by comparison with one or multiple features from field evidence, based on proximity and conformity values. In an example application drawn from glacial geomorphology, APCA is integrated into an overall model verification process that includes matching modeled ice sheets to known marginal positions and ice flow directions, among other parameters. APCA is not limited to ice sheet or glacier models, but can be applied to many geoscience areas where the extent or geometry of modeled results need to be compared against field observations, such as debris flows, tsunami run-out, lava flows, or flood extents.

Identifying patterns of correspondence between modeled flow directions and field evidence: An automated flow direction analysis

Comparison of numerical model output that predicts spatial flow patterns against field observations is a necessity within several areas of the geosciences. However in many cases these comparisons are qualitative or relative in nature. Automated flow direction analysis (AFDA) is a new method designed to provide a systematic comparison between modeled flow patterns and field observations, with particular focus on two-dimensional linear features representing flow directions of natural phenomena. By subtracting vector output of time-dependent models from field-observed directions, the resultant mean residual and variance of the offset between these data sets can be used to identify patterns of correspondence and variation between model-predicted directions and field observations. The technique is demonstrated by comparison of modeled basal ice flow directions of the Fennoscandian Ice Sheet with observed lineations mapped in Northern Sweden. In this example, the analysis provides an effective means to quantitatively validate the modeled basal thermal and flow regime with observed glacial lineations. The technique has potential applications in a wide range of flow vector direction comparisons in the geosciences, for example lava flow, landslides, aeolian and fluvial processes.

A revised automated proximity and conformity analysis method to compare predicted and observed spatial boundaries of geologic phenomena

Quantitative assessment of the level of agreement between model-predicted and field-observed geologic data is crucial to calibrate and validate numerical landscape models. Application of Geographic Information Systems (GIS) provides an opportunity to integrate model and field data and quantify their levels of correspondence. Napieralski et al. [Comparing predicted and observed spatial boundaries of geologic phenomena: Automated Proximity and Conformity Analysis (APCA) applied to ice sheet reconstructions. Computers and Geosciences 32, 124-134] introduced an Automated Proximity and Conformity Analysis (APCA) method to compare model-predicted and field-observed spatial boundaries and used it to quantify the level of correspondence between predicted ice margins from ice sheet models and field observations from end moraines. However, as originally formulated, APCA involves a relatively large amount of user intervention during the analysis and results in an index to quantify the level of correspondence that lacks direct statistical meaning. Here, we propose a revised APCA approach and a more automated and statistically robust way to quantify the level of correspondence between model predictions and field observations. Specifically, the mean and standard deviation of distances between model and field boundaries are used to quantify proximity and conformity, respectively. An illustration of the revised method comparing modeled ice margins of the Fennoscandian Ice Sheet with observed end moraines of the Last Glacial Maximum shows that this approach provides a more automated and statistically robust means to quantify correspondence than the original APCA. The revised approach can be adopted for a wide range of geoscience issues where comparisons of model-predicted and field-observed spatial boundaries are useful, including mass movement and flood extents.

GIS and field-based spatiotemporal analysis for evaluation of paleo-ice sheet simulations

Abstract Reconstructing paleo–ice sheets is significant for paleoclimate reconstructions and evaluations of sea level low stands. Accurate reconstructions of paleo–ice sheet dimensions and dynamics necessitate the combination of field evidence and process modeling. In this study, a GIS-based technique was developed to quantitatively assess model output against geomorphic data. However, implementation of this technique is not straightforward and requires consideration of time-space relationships, data representation, resolution, and analytical design. Combined use of two software tools holds considerable promise for the use, application, and interpretation of refined ice sheet models.

Suburban Food Security: Walkability and Nutritional Access in Metropolitan Detroit

This article explored the relationship between the local food environment and walkability in the socioeconomically diverse, inner-ring suburbs of metropolitan Detroit. The availability and cost differentials of food were surveyed using a modified version of the Nutrition Environment Measures Survey for Stores (NEMS–S), and a geographic information system–based method was designed to map walkability relative to licensed food retail establishments. Results showed that minority communities lack access to fresh produce and nutritionally adequate foods, which is compounded by limited mobility. By incorporating local-based economic incentives, low-income communities can better align neighborhood goals of obtaining nutritionally adequate food (and other services) with economic opportunity.

Broadening Diversity in the Geosciences Through Teacher-Student Workshops That Emphasize Community-Based Research Projects

ABSTRACT The Geosciences Institute for Research and Education at the University of Michigan–Dearborn has been an example of a successful and effective model in increasing the participation of underrepresented groups in the geosciences. The program emphasizes involving middle school and at-risk high school students from the Detroit area public schools, along with their teachers in geoscience research projects, through a series of spring and summer workshops. The workshops introduce students to the geosciences by emphasizing how geology can be used as a tool to solve community-based environmental problems. Students work alongside their teachers and university faculty on projects ranging from an assessment of brownfield sites in southwestern Detroit to the installation of groundwater monitoring wells to the evaluation of how former land use is impacting groundwater and surface water quality. Spring workshops focused on students from three African-centered middle schools in Detroit, while the summer workshops focused more on middle school and high school teacher training, but included a small group of middle school and high school students. Instruments used to evaluate the effectiveness of the workshops included the Science Teaching Efficacy Belief Instrument, the Geoscience Concept Inventory, and survey questions from the Watershed Task. Pre- and postworkshop questionnaires and separate teacher–student focus groups demonstrate that we have not only increased student awareness of the geosciences, but we have also motivated students to pursue career opportunities in science. For example, more than half of the students completing the workshop (boys and girls alike) have expressed a strong interest in pursuing a career in the geosciences. Since its inception in 2005, we have reached over 100 middle and high school students, and 75 teachers. During this same period, the Earth Science major at the University of Michigan–Dearborn has tripled in size, and we have quadrupled the number of minority students taking introductory geology courses.

A century of stream burial in Michigan (USA) cities

ABSTRACT Following rapid expansion of urbanization over the last century, Michigan’s largest cities are characterized by relatively high population densities, high percentages of impervious surface coverage, and heavily modified stream networks (e.g. channelization, dams, or burial). Unfortunately, urban stream burial can be extensive and costly, but the spatiotemporal pattern of stream burial in most cities remains ambiguous and, for the most part, unmapped. This map illustrates the impact of stream removal in Michigan’s seven largest cities, both before and after rapid population growth and industrialization. Flowlines indicating the location of streams, artificial channels, and canals/ditches were accessed from the United States Geological Survey (USGS) National Hydrography Dataset (NHD) and digitized off historical USGS topographic maps between 1902 and 1929, ranging in scale between 1:62,500 and 1:24,000. A comparison between the two datasets showed all seven cities have stream networks altered or lost entirely to the practice of stream burial and removal. The City of Detroit has lost at least 85% of the stream channels since 1902, while other cities, such as Ann Arbor and Warren, have lost more than 60% of the stream network.