The analysis of the form of the Earth's terrain has lagged significantly behind research of the processes that produce those forms in geomorphology. Furthermore, a considerable amount of geomorphic research has focused on two-dimensional analyses that quantify shape rather than the three-dimensional spatial form of surficial features. These emphases have produced a situation whereby current understanding of continuous terrain is not equated with repeatable, measurable attributes but rather with qualitative or simplified empirical interpretations. This Faculty Early-Career Development (CAREER) award will support research to quantitatively assess the three-dimensional form of alluvial fans. Alluvial fans are depositional features that result from sedimentary deposition of alluvium, debris flows, colluvium, or a combination of all three at the foot of a steep slope. The objectives of this line of research are to produce a detailed understanding of alluvial fan form and to use this information to generate a precise process-response model explaining fan evolution in arid as well as humid environments. High-resolution terrain data for a set of alluvial fans will be gathered using global positioning system (GPS) surveying, airborne laser-swath mapping (ALSM), and soft-copy photogrammetry techniques. The investigator will convert the terrain data into grid-based digital elevation models (DEM). In addition, spatial information on fan sedimentary units will be gathered using ground-penetrating radar (GPR). The DEM and sedimentary data will be integrated, stored, analyzed, and visualized using a geographic information system (GIS). Several geostatistical and spatial statistical procedures will be performed to analyze the spatial arrangement and relationships of the internal and external structure identified in the alluvial fans. The spatial relationships will be used to produce the process-response model. The model will be innovative because form will have equally quantifiable measures to compare with the depositional units. The study results and data will be readily transferable to the classroom providing active-learning experiences based on innovative data collection, theory, and analytical educational experiences at the undergraduate and graduate levels. The investigator intends to get underrepresented students participating in research and assisting them by fostering a dynamic student-centered learning environment
The anticipated outcomes of this research should provide a quantitative explanation for similarity and differences between fans generated from disparate processes as well as an assessment of how form varies under different environmental settings. The findings will show how the spatial arrangement of sedimentary units impacts alluvial fan surface morphology. Quantification of alluvial fan form and its relation to formative processes are topics with scientific, applied, and educational merit. The use of arithmetical and statistical techniques will provide repeatable and comparative values that will advance the understanding of form in geographic science. The capacity of the current research to produce accurate information on fan form promotes direct application of these measures for improving conditions of human settlements and protecting them from natural hazards. Urban sprawl in many cities throughout the world has caused development to expand onto fan surfaces. Inhabiting these environments places people at risk and puts a burden on society to pay for damages from flooding and debris flows. Scientific inquiries are beginning to unravel some of the causal mechanisms associated with flooding, channel avulsion, and debris flows on fans, and this study will elucidate how they link to fan morphology. Precise information about alluvial fan form therefore should help produce better tools for hazard mitigation and a firmer factual knowledge base that engineers can use to develop safer building pads and structures. The project also will provide integrative learning opportunities for undergraduate and graduate students.
