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Core Ideas Photogrammetric techniques for spatiotemporal measure of topographic data Physical data for validation and development of soil erosion modeling technology Automated analysis presentation package Rill and ephemeral gully monitoring at high spatial and temporal resolution When flowing water concentrates on hillslopes, the erosivity of the water may only be limited by the erodibility of the soil. Over time, concentrated flow paths may become permanent drainage channels, and such rills and ephemeral gullies often have negative impacts on crop yield and downstream sedimentation. Spatiotemporal topographic assessments of rill and gully dimensions compliment hydraulic erosion estimates, and they can elucidate soil erosion processes and provide data for model validation. Accurate and detailed topographic assessments, however, can be cost prohibitive. The objectives of this study are to describe and evaluate a topographic assessment method with relatively high spatial and temporal resolution, to discuss its costs and limitations, and to provide an assessment procedure for erosion characterization and data optimization. Three locations are evaluated that are pertinent to soil erosion research on the field, plot, and laboratory scale. In each setting, the sites are monumented and monitored using photogrammetric techniques. Photogrammetry is a simple, robust means to track landscape evolution and morphodynamic changes in rills and ephemeral gullies. The assessment procedure describes study site attributes at a variety of spatial and temporal scales, it is cost‐effective, workforce empowering, and reliable, and the analysis and presentation can be automated. Capturing this type of information is critical to an improved understanding of the fundamental principles necessary to enhance modeling technology to estimate erosion potential at various scales and to assess the efficacy of conservation practices.

Concentrated surface runoff, such as associated with ephemeral gully channels, increases erosion and transfers fine sediment and associated agrichemicals from upland areas to stream channels. Ephemeral gully erosion on cropland may contribute up to 40 % or more of the sediment delivered to the edge of agricultural fields, significantly threatening the health of downstream ecological services. Typically, conservation practices developed for sheet and rill erosion are also expected to treat ephemeral gully erosion, but technology and tools are needed to account for the separate benefits and effects of practices on various sediment sources. Without improved research studies, subjective observations will continue to be used to satisfy quality criteria in lieu of scientifically defensible, quantitative methods to estimate the impact of gully erosion. Ephemeral gully channels evolve by one, or combination of, complex physical process in the form of incision, headcut migration upslope, and channel sidewalls expansion (widening). This study focused on the latter, ephemeral gully channel widening relationships. The impact of various width functions on erosion can be very significant and is dependent on discharge, slope, soil properties, and management conditions. A description

BackgroundMarine diseases are of increasing concern for coral reef ecosystems, but often their causes, dynamics and impacts are unknown. The current study investigated the epidemiology of Aplysina Red Band Syndrome (ARBS), a disease affecting the Caribbean sponge Aplysina cauliformis, at both the individual and population levels. The fates of marked healthy and ARBS-infected sponges were examined over the course of a year. Population-level impacts and transmission mechanisms of ARBS were investigated by monitoring two populations of A. cauliformis over a three year period using digital photography and diver-collected data, and analyzing these data with GIS techniques of spatial analysis. In this study, three commonly used spatial statistics (Ripley’s K, Getis-Ord General G, and Moran’s Index) were compared to each other and with direct measurements of individual interactions using join-counts, to determine the ideal method for investigating disease dynamics and transmission mechanisms in this system. During the study period, Hurricane Irene directly impacted these populations, providing an opportunity to assess potential storm effects on A. cauliformis and ARBS.ResultsInfection with ARBS caused increased loss of healthy sponge tissue over time and a higher likelihood of individual mortality. Hurricane Irene had a dramatic effect on A. cauliformis populations by greatly reducing sponge biomass on the reef, especially among diseased individuals. Spatial analysis showed that direct contact between A. cauliformis individuals was the likely transmission mechanism for ARBS within a population, evidenced by a significantly higher number of contact-joins between diseased sponges compared to random. Of the spatial statistics compared, the Moran’s Index best represented true connections between diseased sponges in the survey area. This study showed that spatial analysis can be a powerful tool for investigating disease dynamics and transmission in a coral reef ecosystem.

Abstract. Spatio-temporal measurements of landform evolution provide the basis for process-based theory formulation and validation. Over time, field measurements of landforms have increased significantly worldwide, driven primarily by the availability of new surveying technologies. However, there is no standardized or coordinated effort within the scientific community to collect morphological data in a dependable and reproducible manner, specifically when performing long-term small-scale process investigation studies. Measurements of the same site using identical methods and equipment, but performed at different time periods, may lead to incorrect estimates of landform change as a result of three-dimensional registration errors. This work evaluated measurements of an ephemeral gully channel located on agricultural land using multiple independent survey techniques for locational accuracy and their applicability in generating information for model development and validation. Terrestrial and unmanned aerial vehicle photogrammetry platforms were compared to terrestrial lidar, defined herein as the reference dataset. Given the small scale of the measured landform, the alignment and ensemble equivalence between data sources was addressed through postprocessing. The utilization of ground control points was a prerequisite to three-dimensional registration between datasets and improved the confidence in the morphology information generated. None of the methods were without limitation; however, careful attention to project preplanning and data nature will ultimately guide the temporal efficacy and practicality of management decisions.