Laboratory investigation on measuring suspended sediment by portable laser diffractometer (LISST) focusing on particle shape

This paper deals with a laboratory investigation on measuring suspended sediment volume and mass concentration (SSC) and particle size distribution (PSD) by a portable submersible laser diffractometer (LISST-100X) focusing on effects of particle shape and inversion modes on the results. Experiments were carried out in a mixing tank using suspensions of glass beads, fine quartz sand, feldspar and mica powder particles of spherical, rounded, angular and flaky shapes respectively, at various SSCs. SSCs and PSDs measured by LISST were compared to SSCs from gravimetric analysis and to PSDs obtained from image analysis of dry particles and from a non-portable laser diffractometer. Experiments using spherical and rounded particles showed that LISST with the corresponding inversion modes, i.e. spherical and ‘random shaped’, provides PSD and SSC values similar to reference methods. For angular and flaky particles, however, SSCs were found to be overestimated by factors of 1.5 and 8 respectively. Measurements in a mixture of 70% feldspar and 30% mica powders showed that the SSC overestimation factor for mixed particle-type suspensions can be predicted as the weighted sum of the SSC factors of the components and their mixing ratio. For known highly non-spherical particle types, LISST SSCs can be corrected by a gravimetrically determined or predicted overestimation factor. Moreover, correction of overestimated contributions of lower size bins, the range of measureable SSC and time averaging of LISST measurements are addressed. Further investigations are necessary to assess effects of non-spherical particles and mixtures of various particle types on LISST SSC and PSD estimates.     

Simulations of Coastal Fog in the Canadian Atlantic with the Weather Research and Forecasting Model

Boundary-Layer Meteorology - We evaluate the efficacy of microphysics and planetary-boundary-layer (PBL) parametrizations of the Weather Research and Forecasting (WRF) model for simulation of the...     

Flood prediction and mitigation in coastal tourism areas,a case study: Hurghada,Egypt

Flood mitigation involves the management and control of floodwater movement, such as redirecting flood runoff through the use of floodwalls and flood gates, rather than trying to prevent floods altogether. The prevention and mitigation of flooding can be studied on three levels: on individual properties, small communities, and whole towns or cities. The current study area is located in Hurghada on the Red Sea, which is considered an important area for coastal tourism. The study area is located at distance 7.50 km from El Gouna city along the Red Sea and east of Hurghada–Al Ismaileya road. The aim of this research is to derive the runoff flow paths across the study area and their flow magnitudes under different rainfall events of 10, 25, 50, and 100 year return periods in order to design the flood mitigation measures to protect such important areas. Field data (e.g., topographic data and rainfall intensities) were collected for the study area. The results indicated that the site is exposed to high flash flood risk and protection work is required. In order to protect the area from flood risks, locations of number of drainage channels and dams were selected and designed based on flood quantity and direction. The proposed mitigation system is capable of protecting this crucial area from flood risks and increases the national income from tourism. This study can be applied in different areas of Egypt and the world.     

Structural geologic control with the limestone bedrock associated with piling problems using remote sensing and GIS: a modified geomorphological method

Geotechnical engineering and unpredictable piling problems of highly urbanized areas underlain by intensive geological fracture zones require a better understanding of their spatial pattern and developments. Unlike traditional techniques which use geophysical survey and visual interpretation of optical satellite images, this study presents a modified approach to revealing the buried geological fractures in karst terrain, which incorporates Wood??s algorithm. The algorithm binary maps were modified by applying additional Soble filter with 10% threshold and equalization enhancement. These modifications have proven good discrimination for morphological linear and curvilinear derived from DEM. Results of the modified method were compared to the existing geological map and validated by conducting field observations. The analysis of the results and corresponding geological and topographical maps showed the effectiveness of the method to recognize the pattern of buried geological fractures. The results obtained demonstrated that maps of the modified method can be used as a reference map prior to any site investigation.     

Deficiencies of the vertical slice method in assessment of the seismic earth pressures

Acta Geotechnica - Conventionally, when the method of slice is adopted to assess the earth pressures behind the retaining wall considering a curvilinear failure surface, the mobilized soil mass...     

Prediction of visibility in the Arctic based on dynamic Bayesian network analysis

With the accelerated warming of the world, the safety and use of Arctic passages is receiving more attention.Predicting visibility in the Arctic has been a hot topic in recent years because of navigation risks and opening of ice-free northern passages. Numerical weather prediction and statistical prediction are two methods for predicting visibility. As microphysical parameterization schemes for visibility are so sophisticated, visibility prediction using numerical weather prediction models inclu...     

Large-Scale Synoptic Systems and Fog During the C-FOG Field Experiment

Boundary-Layer Meteorology - The goal of this work is to summarize synoptic meteorological conditions during the Coastal Fog (C-FOG) field project that took place onshore and offshore of the Avalon...     

Environmental and depositional characteristics of diatomite deposit, Alayunt Neogene Basin (Kutahya), West Anatolia, Turkey

This paper describes the geological-depositional and environmental characteristics of diatomite. The diatomite deposit is situated in the southern part of the Alayunt (Kutahya) Basin. Samples of 18 diatomites and 12 host rocks were collected from four sedimentary profiles in the spring season. Basement rocks are Paleozoic-aged metamorphic rocks (schist, phyllite, quartzite, etc.) and Mesozoic-aged ophiolitic and complex rocks. Host rocks are rhyodacitic–rhyolitic tuffite, volcanic glass. Diatomite is composed of Upper Miocene–Upper Pliocene-aged diatom species. Diatomite shows layer morphology and lies on volcanic glass layer. XRD characteristic peaks of diatomite show that it comprises dominantly of Opal-A silica, whereas volcanic glass has Opal-CT constituent. SEM and NPM photomicrographs indicate that diatomites are dominantly composed of benthic freshwater diatom species, such as Pinnularia microstauron, Pinnularia lundii, Pinnularia subrostrata, Pinnularia brevicostata, Pinnularia tenuis, Pinnularia sp., Navicula eligensis, Fragilaria construens, Mastogloia braunii Grunow, Melosira varians Agardh, Surirella capronii Brébisson, Cymbella lanceoloata, Amphora venata, Gomphonema germainii, Gomphonema angustatum and Rhapalodia gibba. These species are general indicators of shallow paleolake environment and cool climate conditions. Due to the fluvial currents and climatic conditions; lake water levels, temperature and nutrient content fluctuated through the time. Chemical data obtained from 18 diatomite samples show that while silica is the bodybuilding material for diatomite (over 89 % SiO₂), Al, Mg and Fe contents of diatomite samples might be derived from clastic materials. The concentration of Al, Mg and Fe decreases toward the lake center. Diatom genera, sedimentary profile sections and mineralogic data suggest that diatomite deposited in lacustrine-type freshwater shallow lake is associated with Upper Miocene-aged extension tectonics. Physical and filtration tests along with environmental characteristics of diatomite suggest that calcined diatomite can be used for waste treatment processes in the filter aid industry.     

Comparative Evaluation for Characterization of Produced Water Generated from Oil,Gas, and Oil–Gas Production Fields

A reliable wastewater characterization is a prerequisite for the selection of an acceptable treatment strategy for produced water which exhibits significant differences due to the varied kinds of wells, seasonal changes, and formation types. A complete characterization of produced water generated from oil, gas, and oil–gas fields in Turkey was performed based on seasonal and locational variations. The results showed that the produced water generated from oil field wells was highly polluted and wastewater volume was higher in comparison to gas and oil–gas field wells. Besides, the characterization of produced water was varying in a wide range based on seasonal and locational variations. Useful relationships were observed between chloride, sodium, bromide, and total dissolved solids concentrations. The results can be used in the design, operation, and optimization of wastewater treatment systems of petroleum and oil industries for future studies.