Aquatic chemistry is becoming both a rewarding and substantial area of inquiry and is drawing many prominent scientists to its fold. Its literature has changed from a compilation of compositional tables to studies of the chemical reactions occurring within the aquatic environments. But more than this is the recognition that human society in part is determining the nature of aquatic systems. Since rivers deliver to the world ocean most of its dissolved and particulate components, the interactions of these two sets of waters determine the vitality of our coastal waters. This significant vol ume provides not only an introduction to the dynamics of aquatic chem istries but also identifies those materials that jeopardize the resources of both the marine and fluvial domains. Its very title provides its emphasis but clearly not its breadth in considering natural processes. The book will be of great value to those environmental scientists who are dedicated to keeping the resources of the hydrosphere renewable. As the size of the world population becomes larger in the near future and as the uses of materials and energy show parallel increases, the rivers and oceans must be considered as a resource to accept some of the wastes of society. The ability of these waters and the sediments below them to accommodate wastes must be assessed continually. The key questions relate to the capacities of aqueous systems to carry one or more pollutants."

Metal pollution in the aquatic environment

Since the IPCC Third Assessment Report (TAR), our understanding of the implications of climate change for coastal systems and low-lying areas (henceforth referred to as ‘coasts’) has increased substantially and six important policy-relevant messages have emerged. Coasts are experiencing the adverse consequences of hazards related to climate and sea level (very high confidence). Coasts are highly vulnerable to extreme events, such as storms, which impose substantial costs on coastal societies [6.2.1, 6.2.2, 6.5.2]. Annually, about 120 million people are exposed to tropical cyclone hazards, which killed 250,000 people from 1980 to 2000 [6.5.2]. Through the 20th century, global rise of sea level contributed to increased coastal inundation, erosion and ecosystem losses, but with considerable local and regional variation due to other factors [6.2.5, 6.4.1]. Late 20th century effects of rising temperature include loss of sea ice, thawing of permafrost and associated coastal retreat, and more frequent coral bleaching and mortality [6.2.5]. Coasts will be exposed to increasing risks, including coastal erosion, over coming decades due to climate change and sea-level rise (very high confidence). Anticipated climate-related changes include: an accelerated rise in sea level of up to 0.6 m or more by 2100; a further rise in sea surface temperatures by up to 3°C; an intensification of tropical and extratropical cyclones; larger extreme waves and storm surges; altered precipitation/run-off; and ocean acidification [6.3.2]. These phenomena will vary considerably at regional and local scales, but the impacts are virtually certain to be overwhelmingly negative [6.4, 6.5.3].

https://ro.uow.edu.au/cgi/viewcontent.cgi?article=1192&context=scipapers

Coastal systems and low-lying areas

Foreword 1. Introduction 2. Runoff, erosion and delivery to the coastal ocean 3. Temporal variations 4. Human impacts Appendices. Global River Database: Appendix A: North and Central America Appendix B: South America Appendix C: Europe Appendix D: Africa Appendix E: Eurasia Appendix F: Asia Appendix G: Oceania References Index.

/pdf/river-discharge-to-the-coastal-ocean-a-global-synthesis-571z1g19ts.pdf

River Discharge to the Coastal Ocean: A Global Synthesis

We provide a brief synopsis of the unique physical and ecological attributes of sandy beach ecosystems and review the main anthropogenic pressures acting on the world's single largest type of open shoreline. Threats to beaches arise from a range of stressors which span a spectrum of impact scales from localised effects (e.g. trampling) to a truly global reach (e.g. sea-level rise). These pressures act at multiple temporal and spatial scales, translating into ecological impacts that are manifested across several dimensions in time and space so that today almost every beach on every coastline is threatened by human activities. Press disturbances (whatever the impact source involved) are becoming increasingly common, operating on time scales of years to decades. However, long-term data sets that describe either the natural dynamics of beach systems or the human impacts on beaches are scarce and fragmentary. A top priority is to implement long-term field experiments and monitoring programmes that quantify the dynamics of key ecological attributes on sandy beaches. Because of the inertia associated with global climate change and human population growth, no realistic management scenario will alleviate these threats in the short term. The immediate priority is to avoid further development of coastal areas likely to be directly impacted by retreating shorelines. There is also scope for improvement in experimental design to better distinguish natural variability from anthropogenic impacts. Sea-level rise and other effects of global warming are expected to intensify other anthropogenic pressures, and could cause unprecedented ecological impacts. The definition of the relevant scales of analysis, which will vary according to the magnitude of the impact and the organisational level under analysis, and the recognition of a physical–biological coupling at different scales, should be included in approaches to quantify impacts. Zoning strategies and marine reserves, which have not been widely implemented in sandy beaches, could be a key tool for biodiversity conservation and should also facilitate spillover effects into adjacent beach habitats. Setback and zoning strategies need to be enforced through legislation, and all relevant stakeholders should be included in the design, implementation and institutionalisation of these initiatives. New perspectives for rational management of sandy beaches require paradigm shifts, by including not only basic ecosystem principles, but also incentives for effective governance and sharing of management roles between government and local stakeholders.

/pdf/threats-to-sandy-beach-ecosystems-a-review-50zdg3kglj.pdf

Threats to sandy beach ecosystems: A review

Author Posting. © Annual Reviews, 2007. This is the author's version of the work. It is posted here by permission of Annual Reviews for personal use, not for redistribution. The definitive version was published in Annual Review of Earth and Planetary Sciences 36 (2008): 601-647, doi:10.1146/annurev.earth.35.031306.140139.

/pdf/coastal-impacts-due-to-sea-level-rise-3e2h8eh3jm.pdf

Coastal Impacts Due to Sea-Level Rise

Modern and ancient wave-cut platforms on Ben Lomond Mountain in central California are broadly similar in shape. They have a seaward slope composed of two segments: a steeper, slightly concave inshore segment, with gradients of generally 0.02 to 0.04 (20 to 40 m/km), and a flatter, planar offshore segment with gradients of 0.007 to 0.017 (7 to 17 m/km). The flattest inshore and offshore gradients measured were, respectively, 0.015 (15 m/km) and 0.005 (5 m/km), suggesting that these are close to minimum gradients for erosional platforms in central California. The inshore segments are generally 300 to 600 m wide and extend to a depth of 8 to 13 m. Platforms are widest in areas where soft sandstone crops out and where there has been least uplift. Major storm waves now break in water 7 to 12 m deep. We conclude that inshore platform segments were associated with storm-wave surf zones and that offshore segments were associated with the zone of deep-water wave transformation. A gradient of 0.005 for the offshore segment would keep wave energy at the bottom constant (Zenkovich, 1967). A steeper gradient for the inshore segment would enable backwash undertow to counteract the strong onshore movement of surf, so that available coarse sediment could be moved laterally. Slopes less than the minimum would so dissipate wave energy in offshore areas that the surf zone would not be able to provide the needed longshore transport for coarse sediment, and beach progradation would result. Thus, platforms have a shape that allows efficient conversion of wave energy into erosion and longshore transport; their seaward gradient is not used for the downhill transport of sediment. Platform gradients decrease with time, at least until the minimum is achieved. Whether the offshore segments were eroded at their existing depths or were eroded by surf zones as sea level rose remains a matter of controversy. Ben Lomond platforms have been uplifted and progressively tilted in a seaward direction, indicating that late Tertiary domical uplift has continued into Quaternary time. Uplift rates have ranged from 0.16 m/1,000 yr near Santa Cruz to 0.26 m/1,000 yr near Greyhound Rock. Tilts have varied from 0.001 (1 m/km) for the lowest prominent platform to 0.009 (9 m/km) for the highest platform (which may be as old as 10 6 yr). Because of uplift, platforms must have been cut at times of eustatically high sea level.

Form, genesis, and deformation of central California wave-cut platforms

The long‐term sustainability of California’s beaches depends on periodic deliveries of sand and gravel from coastal rivers and streams. To assess the long‐term health of California’s beaches, this study characterized the current state of fluvial sediment delivery and quantified, on a littoral cell basis, the cumulative impacts of dams in decreasing annual discharge. Presently, more than 500 dams impound more than 42,000 km2 (or 38%) of California’s coastal watershed area. Flow modeling suggests that by diminishing flood hydrographs, these dams have reduced the average annual sand and gravel flux to 20 major littoral cells by 2.8 million m3/yr (or 25%). In 70% of the streams considered in this study, suspended sediment loads during equivalent discharge events have declined over the past three decades, which indicates that dams have also significantly reduced downstream sediment supplies. Approximately 23% (or 274 km) of the 1193 km of beaches in California are downcoast from rivers that have had s...

https://www.jstor.org/stable/10.1086/345922

Reductions in Fluvial Sediment Discharge by Coastal Dams in California and Implications for Beach Sustainability

Significant sea-cliff erosion and storm damage occurred along the central coast of California during the 1982‐1983 and 1997‐1998 El Nino winters. This generated interest among scientists and land-use planners in how historic El Nino‐Southern Oscillation (ENSO) winters have affected the coastal climate of central California. A relative ENSO intensity index based on oceanographic and meteorologic data defines the timing and magnitude of ENSO events over the past century. The index suggests that five higher intensity (relative values 4‐6) and 17 lower intensity (relative values 1‐3) ENSO events took place between 1910 and 1995. The ENSO intensity index correlates with fluctuations in the time series of cyclone activity, precipitation, detrended sea level, wave height, sea-surface temperature, and sea-level barometric pressure. Wave height, sea level, and precipitation, which are the primary external forcing parameters in sea-cliff erosion, increase nonlinearly with increasing relative ENSO event intensity. The number of storms that caused coastal erosion or storm damage and the historic occurrence of largescale sea-cliff erosion along the central coast also increase nonlinearly with increasing relative event intensity. These correlations and the frequency distribution of relative ENSO event intensities indicate that moderate- to high-intensity ENSO events cause the most sea-cliff erosion and shoreline recession over the course of a century.

Influence of El Niño–Southern Oscillation (ENSO) events on the evolution of central California's shoreline

Long-term cliff retreat and erosion hotspots along the central shores of the Monterey Bay National Marine Sanctuary

Fine-grained sediment delivered to the continental margin of central and northern California is dominated by input from coastal rivers. Suspended sediment from northern California rivers (the Eel, Klamath-Trinity, Mad, Smith, and Mattole Rivers, and Redwood Creek) amounts to 81% of the sediment produced between Point Conception and the Oregon border. Steep and uns Table hillslopes combined with high rainfall and land use alterations produce average annual sediment yields up to nearly $2800 tons/km^{2}$. Offshore circulation during periods of peak sediment discharge is dominated by the northerly flowing Davidson Current. LANDS AT imagery reveals large clockwise gyres that transport suspended sediment at least 100 km offshore in surface waters. Along the central coast the regional sediment yields are less than those along the northern California coast by an order of magnitude. Lower precipitation and numerous impoundments and diversions reduce sediment discharge. The Russian, Sacramento and San Joaquin Rive...

Gary B. Griggs

Papers

Form, genesis, and deformation of central California wave-cut platforms

Reductions in Fluvial Sediment Discharge by Coastal Dams in California and Implications for Beach Sustainability

Influence of El Niño–Southern Oscillation (ENSO) events on the evolution of central California's shoreline

Long-term cliff retreat and erosion hotspots along the central shores of the Monterey Bay National Marine Sanctuary

Sources, Dispersal, and Clay Mineral Composition of Fine-Grained Sediment off Central and Northern California