Geomorphic challenges to restoring Puget Sound beaches

Beaches constitute more than 50% of Puget Sound’s 4000 km shoreline. More than a quarter are armored or buried under fill and many others have been impacted indirectly by changes to adjacent shorelines and to sediment transport regimes. Restoring these beaches typically involves removing bulkheads and groins, excavating historic fill, replacing lost sediment, and replumbing tidal inlets and stream mouths. We often emphasize process-based restoration, but for beaches, what does this mean? Geomorphic processes operating on beaches include erosion, deposition, overwash, sediment supply and transport, stream flow, and shoreline migration. These physical processes in turn impact ecosystems by shaping the distribution of habitats and dictating disturbance patterns. Process-based restoration means allowing sediment to move, flooding to occur, and landforms to migrate, all of which can impact existing ecosystems and threaten the human landscape, adding significantly to project complexity and risk. Successful restoration requires understanding basic beach behavior, but it also involves awareness of the different spatial and temporal scales at which processes occur and recognizing that beach systems are inherently dynamic. Ultimately, we recognize that the goal should be to restore processes, not to create static landscapes, something that will become increasingly relevant in an era of rapidly rising sea levels. We will look at beach projects from around the Salish Sea and examine geomorphic factors that influence their performance. While some of these are fairly site-specific design issues, others are related to the complex challenges of restoring dynamic features in landscapes that continue to evolve over time. The lessons inform not only how we build projects, but what we monitor and how we define restoration in 21st century coastal systems

Feeder Bluffs on Puget Sound: Tools for Improved Management

Much of Puget Sound’s shoreline consists of mixed sand and gravel beaches, dominated by longshore sediment transport and organized into hundreds of discrete littoral cells. Sediment supply within these cells is often provided by erosion of the steep coastal bluffs, which are composed of abundant, coarse-grained Pleistocene sediment. Bluffs that provide beach sediment are referred to as feeder bluffs and are important to the long-term maintenance of Puget Sound beaches. At the same time, development of Puget Sound’s shoreline has led to widespread construction of seawalls and revetments to control bluff erosion, with the unintended consequence of reducing natural sources of beach sediment. Coastal managers are concerned that this will adversely impact beach conditions. Impair nearshore ecological functions, and reduce resilience to rising sea level. Until recently, regional mapping of feeder bluffs existed. In 2012-2013, we combined existing information with new data and completed a sound-wide coverage of eroding bluffs, along with related beach and coastal landforms. Mapping was conducted using detailed field observations, supplemented with geologic information and aerial photographs. Bluffs were categorized based on their potential ability to deliver beach sediment. We found that of Puget Sound’s 4000 km of shoreline, about 2200 km are beaches. Of these about 600 km are feeder bluffs and about 50 km were mapped as exceptional. About 35% of the region’s beaches were mapped as modified or armored. The maps of feeder bluffs will be provided on Ecology’s online Coastal Atlas, allowing access and integration with other nearshore data. In addition, web-based material provides background information on geology and beaches and guidance on how to interpret and apply his information. This will assist planners and resource managers in improving shoreline management, assessing Puget Sound nearshore health, and identifying coastal restoration priorities

Recent progress toward reducing seawalls in Puget Sound

Recovery efforts for Puget Sound have focused on improving shoreline function by reducing seawalls (e.g. rock and concrete bank protection) and encouraging alternatives, such as soft shore protection. Shoreline armor was one of the key stressors identified by the Puget Sound Partnership in 2010 to protect and restore habitat. Armor is one of the Puget Sound Vital Signs, those measures used by the Puget Sound Partnership to track ecosystem health. One of the targets associated with the Vital Sign, a net reduction of the total extent of armor between 2011 and 2020, is tracked using the Hydraulic Project Approval (HPA) permitting database maintained by the Washington Department of Fish and Wildlife. Projects are categorized as new, replacement and removed armor. A summary of permit information indicates that generally, trend in new shoreline armor decreased from 2005 – 2016, while the pace of hard armor removal increased. Two additional targets identified by the Partnership, emphasizes the importance of keeping intact eroding bluffs (locally referred to as feeder bluffs) that maintain Puget Sound beaches, and encouraging the use of softer, nature-based approaches to erosion control. The HPA data, combined with recent detailed mapping of coastal landforms, provide an indication of progress towards the feeder bluff target. Soft shoreline techniques have long been of interest on Puget Sound, but have been slow to be widely adopted. These soft techniques are difficult to categorize, as many are hybrids, combining natural elements and beach nourishment with more conventional rock or concrete structural measures. New technical guidance, combined with increased regulatory emphasis and locally-based outreach efforts, have led to improvements in the implementation and the success of new methods of addressing erosion. We describe significant regulatory, educational, scientific, and restoration efforts focused on this issue in Puget Sound

Armoring on Puget Sound: Progress towards a better baseline

The construction of seawalls and similar structures along Puget Sound’s shoreline impacts geomorphic processes and ecological functions. The extent of shoreline armor has been adopted by the Puget Sound Partnership as a vital sign indicator, is used by local, state, and federal groups as a measure of ecosystem function, and has been employed as a tool for prioritizing restoration actions. As a result, we recognized the importance of accurately characterizing the extent, character, and distribution of shoreline armor. The objectives of our project were to review existing data sources, assess methodologies, identify gaps in data quality or coverage, and to recommend steps for developing a reliable baseline for future monitoring and analyses. Previous efforts have suggested that approximately 27% of the region’s 4000 km of shoreline is armored, but our ability to answer important questions has been hampered by the quality and consistency of datasets, poorly documented methodologies, and the ability to relate armor with other shoreline information. In particular, we had difficulty associating armor with its geomorphic setting – bluffs and spits, small estuaries, river deltas, and artificial human landscapes – which greatly influences ecological impacts, management decisions, and restoration strategies. We noted the need for clear definitions and protocols for mapping and characterizing shoreline structures. Some attributes, such as condition and waterward extent, are ecologically important but difficult to measure. Environmentally friendlier soft or hybrid structures are particularly hard to identify and categorize. Our preliminary results provide a clearer picture of where armoring occurs and where there remain significant problems with data reliability and geographic consistency. We have begun a collaborative process to develop a high quality regional dataset of shoreline armor that will provide better understanding of the impacts of existing armor, a reliable baseline for assessing future change, and a tool to support prioritization for protection and restoration

Astronometry with the Hubble Space Telescope : trigonometric parallaxes of planetary nebula nuclei NGC 6853, NGC 7293, Abell 31 and DeHt 5

Original article can be found at: http://www.iop.org/EJ/journal/1538-3881 Copyright American Astronomical Society. DOI: 10.1088/0004-6256/138/6/1969We present absolute parallaxes and relative proper motions for the central stars of the planetary nebulae NGC 6853 (The Dumbbell), NGC 7293 (The Helix), Abell 31, and DeHt 5. This paper details our reduction and analysis using DeHt 5 as an example. We obtain these planetary nebula nuclei (PNNi) parallaxes with astrometric data from Fine Guidance Sensors FGS 1r and FGS 3, white-light interferometers on the Hubble Space Telescope. Proper motions, spectral classifications and VJHKT2M and DDO51 photometry of the stars comprising the astrometric reference frames provide spectrophotometric estimates of reference star absolute parallaxes. Introducing these into our model as observations with error, we determine absolute parallaxes for each PNN. Weighted averaging with previous independent parallax measurements yields an average parallax precision, σπ/π = 5%. Derived distances are: d NGC 6853 = 405+28 –25 pc, d NGC 7293 = 216+14 –12 pc, d Abell 31 = 621+91 –70 pc, and d DeHt 5 = 345+19 –17 pc. These PNNi distances are all smaller than previously derived from spectroscopic analyses of the central stars. To obtain absolute magnitudes from these distances requires estimates of interstellar extinction. We average extinction measurements culled from the literature, from reddening based on PNNi intrinsic colors derived from model SEDs, and an assumption that each PNN experiences the same rate of extinction as a function of distance as do the reference stars nearest (in angular separation) to each central star. We also apply Lutz-Kelker bias corrections. The absolute magnitudes and effective temperatures permit estimates of PNNi radii through both the Stefan-Boltzmann relation and Eddington fluxes. Comparing absolute magnitudes with post-AGB models provides mass estimates. Masses cluster around 0.57 , close to the peak of the white dwarf mass distribution. Adding a few more PNNi with well-determined distances and masses, we compare all the PNNi with cooler white dwarfs of similar mass, and confirm, as expected, that PNNi have larger radii than white dwarfs that have reached their final cooling tracks.Peer reviewe

Proteins from photosynthetic bacteria

Digitized by Kansas Correctional Industrie