Quantifying impacts of forecast uncertainties on predicted storm surges

In this paper, we propose a framework for quantifying risks, including (1) the effects of forecast errors, (2) the ability to resolve critical grid features that are important to accurate site-specific forecasts, and (3) a framework that can move us toward performance-based/cost-based decisions, within an extremely fast execution time. A key element presently lacking in previous studies is the interrelationship between the effects of combined random errors and bias in numerical weather prediction (NWP) models and bias and random errors in surge models. This approach examines the number of degrees of freedom in present forecasts and develops an equation for the quantification of these types of errors within a unified system, given the number of degrees of freedom in the NWP forecasts. It is shown that the methodology can be used to provide information on the forecasts and along with the combined uncertainty due to all of the individual contributions. A potential important benefit from studies using this approach would be the ability to estimate financial and other trade-offs between higher-cost “rapid” evacuation methods and lower-cost “slower” evacuation methods. Analyses here show that uncertainty inherent in these decisions depends strongly on forecast time and geographic location. Methods based on sets of surge maxima do not capture this uncertainty and would be difficult to use for this purpose. In particular, it is shown that surge model bias can play a dominant role in distorting the forecast probabilities.     

Improving Cascadia subduction zone residents’ tsunami preparedness: quasi-experimental evaluation of an evacuation brochure

Natural Hazards - This study surveyed 227 residents in three US Pacific Coast communities that are vulnerable to a Cascadia subduction zone tsunami. In the Brochure condition, information was...     

Review: “Jacob’s Zoo”—how using Jacob’s method for aquifer testing leads to more intuitive understanding of aquifer characteristics

The interpretation of aquifer responses to pumping tests is an important tool for assessing aquifer geometry and properties, which are critical in the assessment of water resources or in environmental remediation. However, the responses of aquifers, measured by time-drawdown relationships in monitoring wells, are nonunique solutions that are affected by many factors. Jacob’s Zoo is a collection of graphical interpretations that allows students and practitioners to develop an intuitive feel for how natural hydrogeological systems work, and develop a set of skills that provide a better understanding of aquifer properties far beyond interpretation of pumping tests. Jacob’s Zoo, based on the work of Jacob (1950), fosters a deeper understanding, although few practitioners realize the full utility of the method. Jacob CE (1950) Flow of groundwater, In: Rouse H (ed) Engineering Hydraulics, Wiley, New York. P 321–386.

     

A deeply stratified archaeological and sedimentary sequence in the Delaware river valley of the middle Atlantic region,United States

A stratified sedimentary and archaeological sequence over seven meters thick is under investigation on Upper Shawnee Island in the Upper Delaware Valley, Monroe County, Pennsylvania. Artifact deposits identified to date include Early Archaic (7380 B.C.), possible Middle Archaic (4300/3300 B.C.), Late Archaic (1565 B.C.), and Middle and Late Woodland components. This paper focuses on the Early Archaic deposits at approximately 4.3 meters below the surface and the implications that the entire profile has for paleoenvironmental change. The sedimentary sequence represents several major changes in depositional processes. Of special interest is a dramatic decrease in landscape stability and an increase in flood depositions during the mid-Holocene, circa 4300/3300 B.C. Similar changes are evident at archaeological sites in the Middle and Lower sections of the Delaware Valley and appear to be a reflection of regional climatic change.     

The origin of Island mammoths and the quaternary land bridge history of the Northern Channel Islands,California

Pygmy proboscidean remains of Mammuthus exilis occur abundantly in late Quaternary deposits on the Northern Channel Islands, California. On the assumption that ancestral elephants could not have swum to the islands and must therefore have walked out, various land bridges have been hypothesized that link the northern islands to the mainland by a peninsula. Geological evidence for a land bridge, however, is lacking, and new evidence shows that elephants are excellent swimmers and skilled at crossing watergaps. The Santa Barbara Channel was narrowed to only 6 km during glacially lowered sea levels. Modern elephants swim much further, and at speeds ranging from 0.96–2.70 km/hr. Motives for California elephants to cross Pleistocene watergaps are inferred from motives that lead modern elephants in Asia and Africa to cross watergaps. These are the visual and olfactory sensing of islands and of insular food during times of drought or fire-induced food shortage. Diminutive size of M. exilis principally reflects lack of island predators, an adaption to periodic food stress in a finite forage area affected by periodic drought and fire, and an adaptation for keeping population numbers high to maintain genetic variability and to ensure survival despite accidents. A late Quaternary scenario describes the environmental setting of the Santa Barbara Channel and the conditions that led to proboscidean dispersal to the preexistent super-island Santarosae.     

Chemical diffusion of fluorine in jadeite melt at high pressure

The chemical diffusion of fluorine in jadeite melt has been investigated from 10 to 15 kbars and 1200 to 1400°C using diffusion couples of Jadeite melt and fluorine-bearing jadeite melt (6.3 wt.% F). The diffusion profile data indicate that the diffusion process is concentration-independent, binary, F-O interdiffusion. The F-O interdiffusion coefficient ranges from 1.3 × 10^?7 to 7.1 × 10^?7 cm²/sec and is much larger than those obtained by Kushiro (1983) for Si-Ge and Al-Ga interdimision in jadeitic melts. The Arrhenius activation energy of diffusion is in the range of 36 to 39 kcal/mole as compared with 19 kcal/mole for fluorine tracer diffusion in a lime-aluminosilicate melt. The diffusivity and activation energy of F-O interdiffusion vary slightly with pressure, but the pressure dependence of F-O, Al-Ga and Si-Ge interdiffusion may be related to the relative volumes of the interdiffusing species for each pair. The magnitude of chemical diffusivity of fluorine is comparable to that of the chemical diffusivity of water in obsidian melts. The diffusivities of various cations are significantly increased by the addition of fluorine or water to a silicate melt. This fact, combined with the high diffusivity of fluorine, suggests that the F^? ion is the principal diffusing species in dry aluminosilicate melts and that dissolved fluorine will accelerate chemical equilibration in dry igneous melts.     

Dynamics of NH4 + and NO3 − uptake in the water column of the Neuse River Estuary,North Carolina

In an attempt to more fully understand the dissolved inorganic nitrogen dynamics of the Neuse River estuary, ¹⁵NH₄ ⁺ and ¹⁵NO₃ ^? uptake rates were measured and daily depth-integrated rates calculated for seven stations distributed along the salinity gradient. Measurements were made at 2–3-wk intervals from March 1985 to February 1989. Significant dark NH₄ ⁺ uptake occurred and varied both spatially and seasonally, accounting for as much as 95% of light uptake with the median being 33%. Apparent NH₄ ⁺ uptake ranged from 0.001 μmol N 1^?1 h^?1 to 4.2 μmol N 1^?1 h^?1, with highest rates occurring during late summer-fall in the oligohaline estuary. Apparent NH₄ ⁺ uptake was significantly related to NH₄ ⁺ concentration (p<0.01); however, the regression explained <3% of the variation. Daily-integrated NH₄ ⁺ uptake ranged from 0.1 mmol N m^?2 d^?1 to 133 mmol N m^?2 d^?1 and followed the trend of apparent uptake. Annual NH₄ ⁺ uptake of the estuary was significantly lower in 1988 than for any other year. Dark uptake of NO₃ ^? was only 14% of maximum light uptake. Apparent NO₃ ^? uptake rates ranged from 0.001 μmol N 1^?1 h^?1 to 1.84 μmol N 1^?1 h^?1 with highest rates occurring in the oligohaline estuary. Apparent NO₃ ^? uptake was significantly related to NO₃ ^? concentration (p<0.01); however, the regression explained <5% of the variation. In general, NO₃ ^? uptake was only 20% of total dissolved inorganic nitrogen (DIN) uptake. Daily-integrated NO₃ ^? uptake ranged from 0.1 mmol N m^?2 d^?1 to 53 mmol N m^?2 d^?1 and followed similar patterns of apparent uptake. Annual NH₄ ⁺ uptake was 11.39 mol N m^?2 yr^?1, 10.28 mol N m^?2 Yr^?1, 10.93 mol N m^?2 yr^?1, and 7.38 mol N m^?2 yr^?1, and 1.84 mol N m^?2 yr^?1, with the 4-yr mean being 10.0. Annual NO₃ ^? uptake was 3.12 mol N m^?2 yr^?1, 3.40 mol N m^?2 yr^?1, 1.96 mol N m^?2 yr^?1, and 1.84 mol N m^?2 yr^?1, with the 4-yr mean being 2.6. The total annual DIN uptake was more than twice published estimates of phytoplankton DIN demand, indicating that there is an important heterotrophic component of DIN uptake occurring in the water column. The extrapolation of nitrogen demand from primary productivity results in serious underestimates of estuarine nitrogen demand for the Neuse River estuary and may be true for other estuaries as well.     

Late-Wisconsin vegetational changes in unglaciated Eastern North America

Recent pollen and macrofossil data from the Southeast is consistent with a displacement of boreal forest species by over 1000 km during full-glacial time. Data from west of the Appalachians suggests a displacement of some 600 km. Thus boreal forests were developed in a broad area south of the ice margin. Few deciduous forest elements persisted in that region. The displacement appears to have been azonal. There is good evidence to suggest a significant mid-Wisconsin interstadial (23,00036,000 BP) characterized by a more temperate biota.     

Tidal flushing of an estuarine embayment subject to recurrent dinoflagellate blooms

A rhodamine dye tracer study was conducted over eight tidal cycles to investigate mixing and tidal exchange processes in Perch Pond, a Cape Cod embayment subject to recurrent blooms of the toxic dinoflagellate, Gonyaulax tamarensis. Dye injected at the inlet to Perch Pond during flood tide became well-mixed within the pond in one day and was removed at an effective first order rate of 0.36 d^?1, equivalent to a 70% utilization of the maximum possible tidal exchange. This relatively high flushing efficiency can be attributed to a density-driven circulation within the pond, consisting of a subsurface inflow of high salinity dense water on the flood tide followed by removal of lighter surface layers through the shallow inlet during ebb tide. The formation of a frontal convergence near the inlet on flood tide is consistent with the observed distribution of G. tamarensis cysts and shelifish toxicity. It is also clear that phytoplankton like G. tamarensis, whose maximum growth rates approximate the rate of tidal flushing, can only bloom within the embayment by avoiding the outflowing surface waters. Mixing within the pond is probably less efficient and population losses greater during dry periods when the pond salinity is higher and the stratification weaker.     

Measurement of cordgrass,Spartina alterniflora,production in a macrotidal estuary,Bay of Fundy

A one-year field study was conducted of the growth, mortality, and loss dynamics of aSpartina alterniflora low marsh in the Minas Basin, a macrotidal estuary at the head of the Bay of Fundy. Data were used to examine the suitability of four methods for estimating annual net aerial primary production (NAPP) of a marsh subject to energetic tidal flooding. Shoots start to grow in April and reach maximum height (about 0.5 m) and weight in October. Maximum shoot density (900–1,600 m^?2) occurs around June and drops thereafter due to the export of entire shoots. The average shoot produces about seven leaves and at least 2–3 are lost during the growing season. All remaining vegetation dies before the end of November. Methods based on harvesting vegetation underestimated NAPP, especially at lower elevations where export is greater due to more frequent and prolonged tidal flooding. The highest NAPP values, on the order of 500–600 g m^?2 y^?1, were obtained using methods based on the population dynamics of individual shoots. These methods are recommended for energetic tidal environments because they include the production of vegetation exported during the growing season.