This book presents a detailed analysis of processes affecting fluvial discharge of water, sediment and dissolved solids to the ocean, covering 1534 rivers, with full quantitative data also available online. A key resource for researchers, professionals and graduate students in hydrology, oceanography, geomorphology and environmental policy. Now available in paperback with corrections.
"Rivers provide the primary link between land and sea. Utilizing the world's largest database, this book presents a detailed analysis and synthesis of the processes affecting fluvial discharge of water, sediment and dissolved solids. The ways in which climatic variation, episodic events, and anthropogenic activities - past, present and future - affect the quantity and quality of river discharge are discussed in the final two chapters. The book contains 26 tables and more than 165 figures - many in full color - including global and regional maps. The book's extensive appendix presents the 1534-river database as a series of 44 tables that provide quantitative data regarding the discharge of water, sediment and dissolved solids. The complete database is also presented within a GIS-based package available online at www.cambridge.org/milliman. River Discharge to the Coastal Ocean provides an invaluable resource for researchers, professionals and graduate students in hydrology, oceanography, geology, geomorphology and environmental policy"--
Freshwater provided from river discharge influences the dynamics and circulation of most continental shelves around the world. It has profound effects on the transport and fate of materials and substances originated from rivers and estuaries, as well as on the ocean biogeochemistry and marine ecosystems. The effect of buoyancy forcing and its modification by windstress off the Oregon coast are studied here, with an emphasis on the downwelling season (fall/winter). Six years of data are used in this study, from 2006 to 2012, obtained by a network of coastal oceanographic observations. During the downwelling season, buoyancy-forcing resulting from significant freshwater input from multiple river sources along the coast, together with the predominantly downwelling-favorable windstress and the large-scale Davidson Current, drives what we have named the Oregon Coastal Current (OCC). Based on a 2-layer model, the dominant forcing mechanism of the OCC is buoyancy, followed by the Davidson Current, and then the wind stress, accounting for 61% (±22.6%), 26% (±18.6%) and 13% (±11.7%) of the along-shore transports, respectively. The OCC is a surface-trapped coastal current, with transports comparable to the summertime upwelling jet off the Oregon coast. Offshore of the OCC, the seasonal evolution of the salinity field is controlled by different mechanisms at two distinct times: prior and after the remotely forced spring transition (RFST). After the RFST, along-shelf advection of the Columbia River Plume by remotely forced southward currents dominate the salinity variability. Prior to the RFST, this variability is dominated by cross-shelf freshwater fluxes from the OCC, influencing an offshore distance of approximately 33 km from the OCC's edge. The rate-of-change of salinity over this region can be explained in terms of eddy and wind-driven Ekman cross-shelf freshwater fluxes, however it was not possible to distinguish their relative contributions. Based on the estimated freshwater loss from the OCC, a leaking pipe model was developed, and it was estimated that the along-shelf freshwater fluxes through a cross-shelf section off Newport can be explained by the summed discharges from 3-4 rivers upstream, reaching as far as the Siuslaw of Umpqua rivers. Salinity off Oregon is also variable at interannual time scales. Low salinities during the upwelling season (spring/summer), produced by increased river discharges from the Columbia River are correlated to El Niño/La Niña. The lowest salinity recorded off Newport, was registered during an extreme La Niña event of 2011. For the first time the Columbia River Plume was tracked from mid-shelf all the way into the Yaquina Bay estuary. Finally, the effect of wind-forcing and flow-topography interaction are investigated, in a continental shelf in the absence of freshwater input, off the Brazilian coast. Our results demonstrate that on larger scales, the sea surface temperature variability along the coast is mainly controlled by wind-driven upwelling, while upwelling due to flow-topography interaction is responsible for the smaller scale sea surface temperature variability.
A comprehensive, state-of-the-art synthesis of biogeochemical dynamics and the impact of human alterations at major river-coastal interfaces for advanced students and researchers.
Rivers smaller than the Amazon tend to be excluded from earth system modeling efforts. Does it matter? Do sub-grid-scale rivers have significant impacts on offshore primary productivity? Using the Eel River in northern California, the river with the largest sediment yield per drainage area in the continental United States, as a test case, this question is explored using two approaches. First, a data-driven analysis of relevant time series taken on land, by buoy, and from space, demonstrates very little evidence of direct impact of Eel River discharge on contemporaneous coastal ocean primary productivity - but to the extent that that evidence exists, it seems to occur during years of greatest river discharge. To further analyze mechanistic drivers, a coupled mesoscale modeling framework unifying ocean, watershed and atmospheric representations is formulated and run in hindcast over the 2002-2010 period. Monthly average climatologies, interannual variabilities, and event-driven analysis of each year's largest river discharge are all examined for evidence of a river-ocean connection expressed through primary production. Storm event-generated turbulence appears to dominate the primary productivity during the winter months. The impact of the river seems to be largely independent of nutrient load, because its dissolved nitrate is less than that of the coastal ocean. There is no evidence that riverine delivery of gradually bioavailable detritus has a significant effect. Although a sufficiently super-nitrous river shows the ability to sustain a plume-nutrient-driven-bloom even at periods of extremely low flow, this is not currently a realistic scenario for the Eel River. The possibility remains that another micronutrient not studied in the modeling framework, such as iron, could be important to this system.
Tide gauges show that global sea level has risen about 7 inches during the 20th century, and recent satellite data show that the rate of sea-level rise is accelerating. As Earth warms, sea levels are rising mainly because ocean water expands as it warms; and water from melting glaciers and ice sheets is flowing into the ocean. Sea-level rise poses enormous risks to the valuable infrastructure, development, and wetlands that line much of the 1,600 mile shoreline of California, Oregon, and Washington. As those states seek to incorporate projections of sea-level rise into coastal planning, they asked the National Research Council to make independent projections of sea-level rise along their coasts for the years 2030, 2050, and 2100, taking into account regional factors that affect sea level. Sea-Level Rise for the Coasts of California, Oregon, and Washington: Past, Present, and Future explains that sea level along the U.S. west coast is affected by a number of factors. These include: climate patterns such as the El Niño, effects from the melting of modern and ancient ice sheets, and geologic processes, such as plate tectonics. Regional projections for California, Oregon, and Washington show a sharp distinction at Cape Mendocino in northern California. South of that point, sea-level rise is expected to be very close to global projections. However, projections are lower north of Cape Mendocino because the land is being pushed upward as the ocean plate moves under the continental plate along the Cascadia Subduction Zone. However, an earthquake magnitude 8 or larger, which occurs in the region every few hundred to 1,000 years, would cause the land to drop and sea level to suddenly rise.
Environmental problems in coastal ecosystems can sometimes be attributed to excess nutrients flowing from upstream watersheds into estuarine settings. This nutrient over-enrichment can result in toxic algal blooms, shellfish poisoning, coral reef destruction, and other harmful outcomes. All U.S. coasts show signs of nutrient over-enrichment, and scientists predict worsening problems in the years ahead. Clean Coastal Waters explains technical aspects of nutrient over-enrichment and proposes both immediate local action by coastal managers and a longer-term national strategy incorporating policy design, classification of affected sites, law and regulation, coordination, and communication. Highlighting the Gulf of Mexico's "Dead Zone," the Pfiesteria outbreak in a tributary of Chesapeake Bay, and other cases, the book explains how nutrients work in the environment, why nitrogen is important, how enrichment turns into over-enrichment, and why some environments are especially susceptible. Economic as well as ecological impacts are examined. In addressing abatement strategies, the committee discusses the importance of monitoring sites, developing useful models of over-enrichment, and setting water quality goals. The book also reviews voluntary programs, mandatory controls, tax incentives, and other policy options for reducing the flow of nutrients from agricultural operations and other sources.
Following a decision by the Arctic Ocean Sciences Board (AOSB) in July 1996 the then chainnan, Geoffrey Holland, wrote a letter of invitation to a meeting to plan a "Symposium on the Freshwater Balance of the Arctic". The meeting was held in Ottawa on November 12-13 1996 and was attended by representatives of various organisations, including the U.S. National Science Foundation (NSF), as well as individual scientists. Results of this meeting included: • Co-sponsorship with AOSB by the Scientific Committee on Ocean Research (SCOR), the Arctic Climate System Study (ACSYS) and the Global Energy and Water Cycle Experiment (GEWEX). • A decision to apply for funding as a Advanced Research Workshop (ARW) of the North Atlantic Treaty Organisation (NATO) Scientific Affairs Division. • That expenses would be covered in part by funds available through an existing NSF grant to the SCOR Executive offices in Baltimore, MD. • The appointment of myself to be Chairman/Manager for the Symposium. • Provision of a recommended list of Scientific Advisors to assist the Chainnan in selecting key speakers.
