Observations of coastal cliff base waves,sand levels,and cliff top shaking

Concurrent observations of waves at the base of a southern California coastal cliff and seismic cliff motion were used to explore wave–cliff interaction and test proxies for wave forcing on coastal cliffs. Time series of waves and sand levels at the cliff base were extracted from pressure sensor observations programmatically and used to compute various wave impact metrics (e.g. significant cliff base wave height). Wave–cliff interaction was controlled by tide, incident waves, and beach sand levels, and varied from low tides with no wave–cliff impacts, to high tides with continuous wave–cliff interaction. Observed cliff base wave heights differed from standard Normal and Rayleigh distributions. Cliff base wave spectra levels were elevated at sea swell and infragravity frequencies. Coastal cliff top response to wave impacts was characterized using microseismic shaking in a frequency band (20–45 Hz) sensitive to wave breaking and cliff impacts. Response in the 20–45 Hz band was well correlated with wave–cliff impact metrics including cliff base significant wave height and hourly maximum water depth at the cliff base (r² = 0.75). With site‐specific calibration relating wave impacts and shaking, and acceptable anthropogenic (traffic) noise levels, cliff top seismic observations are a viable proxy for cliff base wave conditions. The methods presented here are applicable to other coastal settings and can provide coastal managers with real time coastal conditions. Copyright © 2016 John Wiley & Sons, Ltd.     

Characterization of complex fluvial systems using remote sensing of spatial and temporal water level variations in the Amazon,Congo, and Brahmaputra Rivers

The Surface Water and Ocean Topography (SWOT) satellite mission will provide global, space‐based estimates of water elevation, its temporal change, and its spatial slope in fluvial environments, as well as across lakes, reservoirs, wetlands, and floodplains. This paper illustrates the utility of existing remote sensing measurements of water temporal changes and spatial slope to characterize two complex fluvial environments. First, repeat‐pass interferometric SAR measurements from the Japanese Earth Resources Satellite are used to compare and contrast floodplain processes in the Amazon and Congo River basins. Measurements of temporal water level changes over the two areas reveal clearly different hydraulic processes at work. The Amazon is highly interconnected by floodplain channels, resulting in complex flow patterns. In contrast, the Congo does not show similar floodplain channels and the flow patterns are not well defined and have diffuse boundaries. During inundation, the Amazon floodplain often shows sharp hydraulic changes across floodplain channels. The Congo, however, does not show similar sharp changes during either infilling or evacuation. Second, Shuttle Radar Topography Mission measurements of water elevation are used to derive water slope over the braided Brahmaputra river system. In combination with in situ bathymetry measurements, water elevation and slope allow one to calculate discharge estimates within 2.3% accuracy. These two studies illustrate the utility of satellite‐based measurements of water elevation for characterizing complex fluvial environments, and highlight the potential of SWOT measurements for fluvial hydrology. Copyright © 2010 John Wiley & Sons, Ltd.     

Expansion of landscape characterisation methods within the Hydrogeological Landscape Framework: application in the Australian Capital Territory

The Hydrogeological Landscape (HGL) Framework is a landscape-characterisation tool that is used to discern areas of similar physical, hydrogeological, hydrological, chemical and biological properties, referred to as HGL Units. The HGL Framework facilitates prioritisation of natural-resource management investment by identifying current and potential hazards in the landscape. Within prioritised regions, on-ground management actions are tailored for specific Management Areas within individual HGL Units. The HGL Unit boundaries are determined through expert interpretation of spatial and field based datasets, such as climate, landform, geology, regolith, soil, stream network, groundwater flow systems, water quality and vegetation assemblages. The resulting HGL Units are validated by an interdisciplinary team using field assessment and biophysical testing. The use of the HGL Framework for new applications creates opportunities for refinement of the existing methodology and products for end users. This paper uses an application in the Australian Capital Territory as a case study to illustrate two enhanced techniques for the landscape characterisation component of the HGL Framework: use of an unsupervised statistical learning algorithm, Self-Organising Maps (SOM), to further validate HGL Units; and landform modelling to assist in delineation of Management Areas. The combined use of SOM and landform modelling techniques provides statistical support to the existing expert and field-based techniques, ensuring greater rigour and confidence in determination of landscape patterns. This creates a more refined HGL Framework landscape-characterisation tool, facilitating more precise hazard assessment and strategic natural-resource management by end users.     

Impact of river network type on the time of concentration

Time of concentration (T _c) is one of the frequently used parameters to characterize the response of a drainage basin to a rainfall event. Conceptually, it is the time runoff travels from the hydraulically most distant location in a basin to its outlet. T _c was found to vary depending on river basin characteristics such as slope, soil infiltration, and flow path. In this study, we investigate if the drainage network type information can be used as an input to hydrological models, by estimating the time of concentration separately for different network types. Sixty-eight basins which have areas ranging from 24 to 965 km² in arid and non-arid regions of the USA are compared and the effect of climate is also analyzed. It is found that the slope of the linear relationship between T _c and the maximum hydraulic length of flow path shows different correlation coefficients ranging from 0.80 to 0.98 for different network types. It is observed that the slope of the regression line between T _c and the maximum hydraulic length of flow path is the lowest for dendritic networks (slope of 0.26), while pinnate networks have the steepest slope of the regression line (slope of 0.59). This indicates that the drainage network type has a direct impact on the hydrological behavior of the basin and can represent a direct input in hydrological modeling.     

Polyphase tectonic subsidence evolution of the Vienna Basin inferred from quantitative subsidence analysis of the northern and central parts

International Journal of Earth Sciences - The Vienna Basin is a tectonically complex Neogene basin situated at the Alpine–Carpathian transition. This study analyzes a detailed quantification...     

Variability of soil physical and hydraulic properties at the Mojave Global Change Facility,Nevada: Implications for water budget and evapotranspiration

The purposes of this study, conducted at the Mojave Global Change Facility in Nevada, USA, were to examine whether, and to what extent, spatial structure in soil physical properties would manifest as similar spatial structure in hydraulic properties and in spatial differences of evapotranspiration (ET) predictions. Soil samples were collected from 0 to 5 and 5 to 10 cm depths at each of 96 test plots. Hydraulic properties were estimated using textural properties and bulk density in the pedotransfer function method and then examined for spatial structure using variogram analysis. Results show a fining of texture at both depths in the northeast (downslope) quadrant, which led to higher water-holding capacity. Weak spatial structure was observed for most properties (ranges ～75 m). Hydraulic property data were then used as input to a one-dimensional numerical model (HYDRUS-1D) applied at each of the 96 sites for 159 days. Four different shrub cover percentages (0, 10, 20, and 30%) were used. The results showed a predominant soil evaporation-dominated water balance in the northeast quadrant of the site, regardless of plant cover. Elsewhere, plant transpiration was more dominant as percent cover decreased. Results revealed the important role that soil hydraulic properties play in near-surface water balance.     

Sedimentology and sequence stratigraphy of the middle Jurassic Tarbert Formation, Oseberg South area (northern North Sea)

This paper describes the development of a regressive-to-transgressive shoreline wedge within the Middle Jurassic Tarbert Formation in the Oseberg South area (northern North Sea), as interpreted from core and log data from more than hundred wells. The wedge is described in terms of four facies associations (FA1–FA4). The lower, regressive portion of the wedge (FA1–FA2) contains both coarsening upward wave/storm-dominated shoreline deposits as well as coal-bearing paralic deposits, and was deposited during ascending regression. The upper, transgressive portion of the wedge (FA3–FA4) is characterised by wave-dominated estuarine deposits, exhibiting an upward change from inner to central to outer estuarine deposits. In contrast to some earlier studies, it is argued that this part was deposited during accretionary transgression. The present study documents an estuarine system that developed without any preceding fall of relative sea level and valley incision. It is argued that differential fault-induced subsidence created a broad gentle sag wherein one or several estuarine systems developed as the depositional system became transgressive. The subtle fault-induced subsidence is related to the tectonic evolution in the North Sea Basin.     

Determination of Partition Coefficients for Selected PAHs between Water and Dissolved Organic Matter

The fate and transport of highly hydrophobic chemicals are affected by the partitioning between water and dissolved organic carbon. Large variation in the partition coefficient (K_DOCw) is often found, due to the selection of model organic matter or potential experimental artifacts. To investigate the roles of the type of organic matter on the partitioning of highly hydrophobic compounds, the partition coefficients of eight selected polycyclic aromatic hydrocarbons (PAHs), with 3–6 aromatic rings, were determined using a passive dosing/extraction method between water and model dissolved organic matter (humic acid, fulvic acid, sodium dodecyl sulfate micelle (SDS), and 2‐hydroxypropyl‐β‐cyclodextrin). Although the K_DOCw values for 3–4 ring PAHs in this study were close to those reported in the literature, experimental K_DOCw values between Aldrich humic acid (AHA) and water were higher than values reported in the literature for 5–6 ring PAHs. The K_DOCw values were highest for AHA, followed by SDS and Suwannee river fulvic acid (SFA). The slopes of the linear regression between log K_DOCw and log K_ow were 1.23 (± 0.13), 0.82 (± 0.09), and 0.59 (± 0.13) for AHA, SDS, and SFA, respectively. The differences in the K_DOCw values between AHA and the other organic matter (SDS, SFA, and CD) increased with increasing hydrophobicity of the PAHs, showing that the sorption of highly hydrophobic chemicals to the humic acid fraction may be important in the presence of mixed organic matter.     

Characterization of a TCE DNAPL Zone in Alluvium by Partitioning Tracers

Partitioning interwell tracer tests (PITT) were used ID determine the spatial distribution and volume of residual trichloroethene (TCE) present in alluvium beneath the Portsmouth Gaseous Diffusion Plain in southern Ohio. Its first use at this site was in support of the design of a surfactant flood to remove the residual DNAPL (dense nonaqueous phase liquids) from the alluvial aquifer. The second application assessed the performance of the surfactant flood. The average DNAPL saturation in the first PITT was 0.1 to 0.2% in a swept pore volume of 4500 gallons (17.000 L). A second PITT was undertaken following the surfactant flood and yielded an average residual saturation of 0.06% in a swept pore volume of 3400 gallons (13.000 L), the reduction in pore volume being due to the confinement of the tracers to the lower sand and gravel unit of the alluvium. The design, operation, and analysis of the two PM Is provided strong evidence of a buried channel that controls the spatial distribution of the residual TCI: DNAPL in the basal sand and gravel aquifer and must be considered in the eventual full remediation of this aquifer.     

海陆风环流的计算方法

给出海陆风环流的计算方法,得到了计算方程,该方程为一个复偏微分方程,可用松弛迭代法数值求解。利用该方程,对珠江口及香港地区的海陆风环流作了高分辨率的计算,结果表明用该方法计算得到的海陆风环流是可信的,其与实际观测及Mass模式的计算结果十分吻合。