Joseph A. Carlin

Bio: Joseph A. Carlin is an academic researcher from California State University, Fullerton. The author has contributed to research in topics: Fluvial & Holocene. The author has an hindex of 6, co-authored 13 publications receiving 103 citations. Previous affiliations of Joseph A. Carlin include Texas A&M University.

Sediment resuspension by wind, waves, and currents during meteorological frontal passages in a micro-tidal lagoon

Abstract: Meteorological frontal passages are recognized as important mechanisms for remobilizing sediment in estuaries along the northern Gulf of Mexico, but few studies have addressed factors beyond wind speed as a predictor for resuspension. To better understand resuspension mechanisms during these events, this study investigated the effects of wind, waves, and currents on suspended sediment concentration near the seabed during frontal passages in the shallow, micro-tidal West Galveston Bay located along the Texas coast. In late January and early February 2013, two multi-day deployments of instrumented pods (an acoustic Doppler velocimeter, and an acoustic wave and current profiler) were conducted to capture two separate frontal passages. The results indicate that the bed shear stress under the combined effect of waves and currents showed a much stronger relationship to sediment resuspension (R2 = 0.90) than wind stress alone (R2 = 0.55), or currents alone (R2 = 0.72). Increases in the bed shear stress due to the combined effects of waves and currents resulted from increased wave height, which is strongly related to fetch within the bay. Therefore, understanding fetch-limited wave heights as a function of wind speed and direction, in conjunction with basin geometry, may be a better way to predict sediment resuspension during meteorological frontal passages in the shallow bays of the northern Gulf of Mexico.

Evidence for coseismic subsidence events in a southern California coastal saltmarsh

Abstract: Paleoenvironmental records from a southern California coastal saltmarsh reveal evidence for repeated late Holocene coseismic subsidence events. Field analysis of sediment gouge cores established discrete lithostratigraphic units extend across the wetland. Detailed sediment analyses reveal abrupt changes in lithology, percent total organic matter, grain size, and magnetic susceptibility. Microfossil analyses indicate that predominantly freshwater deposits bury relic intertidal deposits at three distinct depths. Radiocarbon dating indicates that the three burial events occurred in the last 2000 calendar years. Two of the three events are contemporaneous with large-magnitude paleoearthquakes along the Newport-Inglewood/Rose Canyon fault system. From these data, we infer that during large magnitude earthquakes a step-over along the fault zone results in the vertical displacement of an approximately 5-km2 area that is consistent with the footprint of an estuary identified in pre-development maps. These findings provide insight on the evolution of the saltmarsh, coseismic deformation and earthquake recurrence in a wide area of southern California, and sensitive habitat already threatened by eustatic sea level rise.

Image Processing

Abstract: MUCKE aims to mine a large volume of images, to structure them conceptually and to use this conceptual structuring in order to improve large-scale image retrieval. The last decade witnessed important progress concerning low-level image representations. However, there are a number problems which need to be solved in order to unleash the full potential of image mining in applications. The central problem with low-level representations is the mismatch between them and the human interpretation of image content. This problem can be instantiated, for instance, by the incapability of existing descriptors to capture spatial relationships between the concepts represented or by their incapability to convey an explanation of why two images are similar in a content-based image retrieval framework. We start by assessing existing local descriptors for image classification and by proposing to use co-occurrence matrices to better capture spatial relationships in images. The main focus in MUCKE is on cleaning large scale Web image corpora and on proposing image representations which are closer to the human interpretation of images. Consequently, we introduce methods which tackle these two problems and compare results to state of the art methods. Note: some aspects of this deliverable are withheld at this time as they are pending review. Please contact the authors for a preview.

Measuring, modelling and projecting coastal land subsidence

Abstract: Coastal subsidence contributes to relative sea-level rise and exacerbates flooding hazards, with the at-risk population expected to triple by 2070. Natural processes of vertical land motion, such as tectonics, glacial isostatic adjustment and sediment compaction, as well as anthropogenic processes, such as fluid extraction, lead to globally variable subsidence rates. In this Review, we discuss the key physical processes driving vertical land motion in coastal areas. Use of space-borne and land-based techniques and the associated uncertainties for monitoring subsidence are examined, as are physics-based models used to explain contemporary subsidence rates and to obtain future projections. Steady and comparatively low rates of subsidence and uplift owing to tectonic processes and glacial isostatic adjustment can be assumed for the twenty-first century. By contrast, much higher and variable subsidence rates occur owing to compaction associated with sediment loading and fluid extraction, as well as large earthquakes. These rates can be up to two orders of magnitude higher than the present-day rate of global sea-level rise. Multi-objective predictive models are required to account for the underlying physical processes and socio-economic factors that drive subsidence. Measuring coastal subsidence is essential to evaluating hazards associated with sea-level rise. This Review discusses the processes driving coastal subsidence, space-borne and land-based measurement techniques, as well as models for simulating observed subsidence and predicting future trends.

Role of delta-front erosion in sustaining salt marshes under sea-level rise and fluvial sediment decline

Abstract: Accelerating sea‐level rise and decreasing riverine sediment supply are widely considered to lead to global losses of deltaic marshes and their valuable ecosystem services. However, little is known about the degree to which the related erosion of the seaward delta front can provide sediments to sustain salt marshes. Here, we present data from the mesomacrotidal Yangtze Delta demonstrating that marshes have continued to accrete vertically and laterally, despite rapid relative sea‐level rise (∼10 mm yr−1) and a > 70% decrease in the Yangtze River sediment supply. Marsh progradation has decelerated at a lower rate than fluvial sediment reduction, suggesting an additional source of sediment. We find that under favorable conditions (e.g., a mesomacrotidal range, strong tidal flow, flood dominance, sedimentary settling lag/scour lag effects, and increasing high‐tide level), delta‐front erosion can actually supply sediment to marshes, thereby maintaining marsh accretion rates in balance with relative sea‐level rise. Comparison of global deltas illustrates that the ability of sediment remobilization to sustain marshes depends on coastal processes and varies by more than an order of magnitude among the world's major deltas.