10-m Depth Research Articles

Prior exposure to elevated pCO2 does not affect calcification of a tropical scleractinian when returned to ambient pCO2

Coral reefs experience biologically-driven pCO2 oscillations that are predicted to become more extreme in magnitude and duration under ocean acidification (OA) regimes. Understanding the plasticity of responses in common reef-building corals to oscillations in pCO2 will allow for better predictions of their function in future seawater conditions. This study explored the effects of variation in seawater pCO2 on coral calcification using experiments conducted over one month between 9 April 2018 and 18 May 2018. Branches (~4-cm long) of Acropora retusa were sampled from colonies at 10-m depth on the fore reef of Mo'orea, French Polynesia (17° 28′ 53.9004" S, 149° 49′ 50.5992" W). We tested the hypothesis that depressed calcification caused by elevated pCO2 (~1000 μatm) is relaxed (i.e., calcification increases) upon return to ambient pCO2 (~400 μatm). Corals first were incubated in ambient or elevated pCO2 for 19 days, with the result that calcification integrated over this period was reduced by 31% under elevated pCO2. The same corals were then incubated at ambient pCO2 for 11 days, during which calcification was independent of the experimental pCO2 exposure history. Our results suggest that a quick relaxation of pCO2-depressed calcification in A. retusa following cessation of high pCO2 indicates that corals are capable of a reversible plastic response of calcification when confronted by pCO2 oscillations.

Spatio-temporal variability of amphipod assemblages associated with rhodolith seabeds

Rhodolith seabeds are habitats underpinned by free-living calcareous macroalgae. We partitioned the relevance of the scale of temporal (four seasons throughout two successive years) and spatial (three depth strata: 18, 25 and 40m) variation on the diversity, structure and abundance of amphipod assemblages living in rhodolith seabeds from Gran Canaria Island. In total, 3996 individuals, belonging to 32 taxa, were identified. Multivariate analyses showed consistent differences in assemblage structure among seasons and depths; more diverse and abundant amphipod assemblages were often observed during spring at 18- and 25-m than at 40-m depth. Ovigerous females of Gammaropsis ostroumowi and Ampithoe ramondi were observed mainly at 18 and 25m. Juveniles of both species were exclusively recorded at 18 and 25m, so denoting a clear segregation in their population structure with depth. In summary, this study has demonstrated that the ecological pattern of amphipods associated with rhodolith seabeds can vary greatly across both time (seasons) and space (depth).

Field Observations of Wave-induced Headland Rips

Most of rip-current field experiments have focused on persistent rips along rip-channeled sandy beaches or transient rips along reasonably alongshore-uniform surf-zone morphology, while experiments on rip flowing against structures are scarce. In October 2018, a 3-week field experiment was performed at Anglet beach, SW France, aiming at examining the dynamics of high-energy rip currents in complex settings. The beach is barred with prominent inherited geology, characterized by the presence of a 500-m headland and a natural submerged reef. A large array of in-situ instruments was deployed to capture the temporal and spatial variability of rip flow circulations, including ADCPs, surf-zone drifters and video monitoring. The latter allowed to identify a wide range of rip-flow patterns. Among these patterns, a high-intensity rip current flowing against the headland was a dominant feature for obliquely incident waves. Such a boundary rip current was driven by the deflection of the longshore current against the headland, peaking at 0.7 m/s (5-min time-and depth-averaged) 800-m offshore in 12-m depth for a moderate storm event with 4-m obliquely incident waves. Very-lowfrequency (O(1h) and O(30min)) fluctuations of this rip current were observed around low tide. Measurements of the vertical structure of the rip reveal that the deflection rip was more vertically-sheared as the water depth increases, with higher velocities near the surface, which is typical of a theoretical rip head structure.

Environmental impact of kelp (Saccharina latissima) aquaculture

The aim of the study was to assess the effect of seaweed cultivation on the coastal environment. We analysed a multitude of environmental parameters using an asymmetrical before after control impact (BACI) design, comparing the seaweed farm (impact) with multiple unaffected locations (controls). The seaweed farm had a significant positive effect on benthic infauna (p<0.05) and was found to attract 17 mobile faunal and 7 other seaweed species, indicating that the farmed crop may provide habitat to mobile faunal species. A light attenuation of approximately 40% at 5m depth was noted at the peak of the seaweed biomass just before harvest. No changes were observed in benthic oxygen flux, dissolved nutrient concentrations, and benthic mobile fauna between farm and control sites. These results show that seaweed aquaculture has limited environmental effects, especially compared to other forms of aquaculture such as fish and bivalve farming.

Volume and Heat Budgets in the Coastal California Current System: Means, Annual Cycles, and Interannual Anomalies of 2014–16

AbstractThe data-assimilating California State Estimate (CASE) enables the explicit evaluation of spatiotemporally varying volume and heat budgets in the coastal California Current System (CCS). An analysis of over 10 years of CASE model output (2007–17) diagnoses the physical drivers of the CCS mean state, annual cycles, and the 2014–16 temperature anomalies associated with a marine heat wave and an El Niño event. The largest terms in the mean mixed layer (from−50 to 0 m) volume budgets are upward vertical transport at the coast and offshore-flowing ageostrophic Ekman transport at the surface, the two branches of the coastal upwelling overturning cell. Contributions from onshore geostrophic flow in the Southern California Bight and alongshore geostrophic convergence in the central CCS balance the mean volume budgets. The depth-dependent annual cycle of vertical velocity exhibits the strongest upward velocity between −40- and −30-m depth in April. Interannual volume budgets show that over 50% of the 2013.5–16.5 time period experienced downwelling anomalies, which were balanced predominantly by alongshore transport convergence and, less often, by onshore transport anomalies. Mixed layer temperature anomalies persisted for the entirety of 2014–16, reaching a maximum of +3° in October 2015. The mixed layer heat budget shows that intermittent high air–sea heat flux anomalies and alongshore and vertical heat advection anomalies all contributed to warming during 2014–16. A subsurface (from −210 to −100 m) heat budget reveals that in September 2015 anomalous poleward heat advection into the Southern California Bight by the California Undercurrent caused deeper warming during the 2015/16 El Niño.

Site response assessment and ground conditions at King Saud University Campus, Riyadh City, Saudi Arabia

Site response characteristics have a significant influence on ground motion vibrations. To evaluate the site response effects at King Saud University campus, the horizontal-to-vertical spectral ratio (HVSR) technique has been applied at 45 sites with about 400-m spacing. The recording time was more than 1 h at each site with a sampling rate of 100 Hz. The data were processed and analyzed using Geopsy software to produce measurements of fundamental frequency and minimum site amplification factor. Moreover, shear-wave velocity down to 30-m depth has been acquired at 10 measuring sites in the campus. In addition, geotechnical borehole data were collected from four boreholes within the campus. Generally, in majority of sites the H/V curve for amplitude spectra displayed a clear peak, signifying the presence of a sharp soil–bedrock impedance contrast between alluvial deposits and underlying bedrock. It is indicated that the fundamental frequency ranges between 0.64 and 1.94 Hz. Given the measured resonance frequency of around 1 Hz, buildings located on the alluvium that have 5 stories in height could experience soil-structure resonance, while the amplification factor varies from 1.19 to 11.22 indicating localized zones having high vulnerability index due to the considerable thickness of alluvial deposits. Moreover, shear-wave velocity ranges between 320 m/s and 684 m/s revealing zones of stiff soil to very dense soil/or soft rock which is correlated well with the geotechnical parameters of borehole data. Based on these results, the ground conditions of near-surface sediments in the King Saud University campus indicate weak zones that led to ground subsidence resulting in differential settlements of foundations.

P Y Curves of Laterally Loaded Piles Near Earth Slopes

Design of piles under lateral loads using numerical analysis is a time-consuming process, requiring competent geotechnical engineers who can accurately model the soil profile and construction sequence. Therefore, most engineers have resorted to the p-y method that is a less time-consuming process in both the modeling and running time. Contrary to the numerical analysis method, the p-y method doesn’t require the burden of constructing a complicated 3D model. This method simply uses the relation between the soil resistance per unit length (p) and the lateral deformation (y) to deduce the straining actions on the pile, bending moment, and shear forces, which govern the structural design. However, the simplicity of this method comes with its shortcomings. The p-y method, for instance, cannot directly take into account the effect of earth slopes on the laterally loaded piles, and its results are somewhat approximate. A well-instrumented case study from the Caltrans site at Oregan State University is analyzed in this research. The studied case consists of a laterally loaded single vertical pile embedded in a cohesive soil layer near an earth slope of 2H:1V. A three dimensional numerical model of the case study is constructed, utilizing the finite element code, Plaxis 3D 2020. The p-y curves of the loaded piles were back-calculated from the numerical model using the elastic beam theory by performing the differentiation of the shear force acting on the pile along the full height of the earth slope. Normalized p-y curves were obtained to determine the p-multiplier, a factor that helps convert the p-y relation of a pile in leveled ground to that of a pile near earth slopes. Overall, it was found that the p-multiplier ranges between (0.4-0.8), (0.6-0.83), (0.8-0.95), and (0.98-1) for piles located at a distance of 0D, 2D, 4D, and 8D respectively from the crest of the earth slope, for various target depths. A parametric study for the effect of the distance of the pile from the crest of the slope, as well as the slope inclination, on the p-y curves was conducted. The curves were constructed for a single pile located at distances of 0D,2D,4D, and 8D from the crest of the earth slope. The performed study revealed that the p-multiplier, at a target depth of 1m, measured from the top of the pile, for the studied slope inclinations, ranges between (0.3-0.45) for the pile at a distance of 0D, (0.76-0.8) at a distance of 2D, (0.82-0.93) at a distance of 4D and (0.98-1) at a distance 8D. Analysis results showed that the effect of slope inclination diminishes when the pile is placed at a distance 8D from the crest or farther. These values can be implemented into p-y curves software, such as LPILE, to determine the straining actions required for design of a laterally loaded pile near sloping ground.

Effects of flooding frequencies on soil carbon and nitrogen stocks in river marginal wetlands in a ten-year period

Wetland hydrology can greatly influence the variations in soil carbon and nitrogen stocks. Soil cores were sampled to a depth of 100 cm at 10 cm intervals above 20 cm soils and 20 cm intervals below 20 cm soils in river marginal wetlands with different flooding frequencies (i.e., permanently flooded, one-year, five-year, ten-year, and one-hundred-year floodplains) in 1999 and 2009, respectively. Soil organic carbon and total nitrogen were measured to investigate spatial and temporal variations in soil organic carbon and total nitrogen stocks in five floodplains with different flooding frequencies on a small scale. The results showed that SOCS ranged from 4.62 kg C/m2 to 13.21 kg C/m2 and TNS from 0.41 kg N/m2 to 2.01 kg N/m2 in the top 1m depth in five zones in both sampling years. Higher soil organic carbon and total nitrogen stocks were observed in these floodplain wetlands with higher flooding frequencies (i.e. permanently flooded, one-year, and five-year floodplains) than those in lower-flooding-frequency floodplains (i.e., ten-year and one-hundred floodplains), and the highest soil organic carbon and total nitrogen stocks in top 10 cm appeared in one-year floodplain rather than permanently flooded floodplain in both years. This indicated that higher flooding frequencies could contribute to soil carbon and nitrogen accumulation due to better hydrological conditions compared with lower flooding frequencies. Soil organic carbon and total nitrogen stocks in top 1m depth decreased by approximately 8–53% and by 22–55% from 1999 to 2009, respectively, of which the highest change rate occurred in one-hundred fooldplain and the lowest in permanently flooded floodplain. The decline in soil carbon and nitrogen stocks of deeper soils mainly caused by heavy alkalinity, reduced water table, and elevated temperature in a ten-year period possibly contribute to explaining the total carbon and nitrogen losses in soil profiles. Correlation analysis showed that soil organic carbon and total nitrogen levels in this region were significantly correlated with flooding frequencies, soil depth, soil pH value, bulk density, soil texture, and microbial biomass. It is necessary to pay much more attention to carbon and nitrogen stocks in deeper soils and find out the key factors that cause carbon and nitrogen loss in these floodplain wetlands to improve carbon sink function of wetland soils. The findings of this work provide a potential explanation for the “missing” carbon sinks at a larger scale.

Study on analysis and design of a VIAM- AUV2000 Autonomous Underwater Vehicle (AUV)

This paper presents the design of the VIAM-AUV2000 autonomous underwater vehicle (AUV) with a built-in cylinder for floatation and counterbalance. The modular structure, including mechanical design, electronic system, and control algorithm, ensures continuous operation for the vehicle at a depth of 50 meters underwater. The main content will consist of two parts: the mechanical implementation and the electrical system. The mechanical implementation part will focus on calculating ship hull profile and material selection; computing and simulating stress and distortion on ship hull and waterproof covering using finite element method with NX Nastran; analyzing and planning cylinder and counterbalance arrangements. At the same time, the advantages of hybrid AUV design inspired from the traditional one with thruster and fins, as well as the underactuated glider form using counterbalance and cylinder for diving and floating, are discussed specifically in the upcoming sections. The electrical system for the robot is also mentioned and clarified through the selection of sensors, actuators, and hardware design to ensure stable operation for the diving robot at a depth of 50m and operate continuously for long periods underwater by using traditional AUV mode and glider mode. Some experimental results of thruster and three-axis tilt estimators with an error of less than 1o are also presented in this paper.

Numerical Analysis of Rapid Drawdown of an Embankment Dam

Numerical analysis for the safe rate determination of lowering of an embankment dam was performed in this study with the use of the finite element method. Coupled deformation and consolidation analysis were carried out for staged construction and drawdown of a 59m embankment dam for varying undrained shear strength of the clay core. The lowering of the reservoir was performed at different depths between two extreme scenarios, i.e. rapid lowering rate (1m/day) and slow lowering rate (0.1m/day). The reservoir of the dam was lowered to a depth from 10m to 55m in gradual increments. The results indicated that the safety of the dam was satisfactory when the reservoir was lowered at the quick rate for a depth of 10m, 20m, 30m respectively when the undrained shear strength of the clay core was taken as 20, 25 and 30kN/m2. Regarding the case of slow drawdown rate of the reservoir, it was found that the reservoir could be lowered up to a depth of 55m at a rate of 0.1m/day when the undrained strength of clay core was 25kN/m2. The stability of the dam was also found satisfactory even though the reservoir was lowered at a rate of 0.25m/day for a depth of 55m when the undrained shear strength of clay core was 30kN/m2.

Influence of Dredge Reamer Operating Parameters on Pollutant Diffusion in Reservoir Dredging

In order to study the influence of pollutant diffusion in the process of reservoir environmental dredging, this paper took the Tongji-bridge reservoir environmental dredging project as an example to analyze the relationship among the reamer rotating speed, traverse speed and slurry absorption concentration, and thus determined the optimal reamer operation parameters. Besides, this paper also monitored and analyzed the impact of pollutant diffusion dispersion in environmental dredging under the condition of the optimal reamer operating parameters. The results turn out: (1)When the reamer rotating speed and traverse speed were set to 15 r/min and 15∼20 m/min, the slurry absorption concentration was higher and the efficiency of dredging was optimal at the moment. (2)Under the optimal reamer operation parameters condition, the pollutant diffusion in the horizontal direction was obviously affected by water depths. The horizontal diffusion distance was about 20m when the water depth was 15m to 20m and the horizontal was increased to be 40m in the depth of 10m to 15m. (3)Under the optimal reamer operation parameters condition, the pollutant diffusion in the vertical direction was little affected by different water depths. The peak of pollutant concentration from high to low was 1.0m above the bottom, intermediate water depth and 1.0m below the water surface.

A new full‐scale testbed for structural health monitoring and soil–structure interaction studies: Kunming 48‐story office building in Yunnan province, China

This paper introduces a new and unique full-scale testbed site for structural health monitoring and soil–structure system identification studies being developed in southwest China. The site is a 48-story skyscraper with an extended four-level basement, supported by piles, located in Kunming, the capital of Yunnan Province. Located in the diffused zone of collision of the Indian and Eurasian tectonic plates, Yunnan is one of the most active seismic areas in mainland China. The final sensor deployment will consist of 43 triaxial accelerometers (129 channels) and one weather station. The accelerometer array comprises (a) a structural array of 25 accelerometers installed at 10 levels aboveground, (b) a basement array of 14 accelerometers distributed in the first and fourth basements, and (c) two borehole arrays installed close to the basement perimeter wall, each with one accelerometers at the surface and another one at 50-m depth, which is the depth reached by the piles. With such dense instrumentation of structure, basement, and pile foundation, this site will be the first permanently instrumented full-scale testbed to enable identification of a soil-foundation–basement-structure system and validation of many assumptions commonly made in the prediction of the soil–structure interaction effects. A high-performance wired local area network has been installed in the building, featuring a Precision Time Protocol-enabled time synchronization and real-time remote access over the Internet. The site will be fully operational in late spring of 2020. Results of preliminary system identification of the structure from ambient vibration test data are presented.

The spatial distribution of nitrate and phosphate in Sempor Reservoir, Kebumen Regency, Central Java

Sempor Reservoir is used for irrigation, domestic, industrial, and tourism purposes, as well as hydroelectric power plant and inland fish farming in pens. The land use in its catchment area is mainly plantation (74%) and, followed by, rice field (8.13%), dry farmland (7.74%), and settlement (5.69%). Agricultural activities, both in irrigated and rainfed farming systems, apply fertilizers to maintain crop quality, but when these substances washed away by surface runoff and transported through the drainage system, they end up increasing nutrients in water bodies. Excess nutrients like nitrate and phosphate induce a rapid growth of algae and aquatic plants, disrupting the ecosystems. This study was designed to identify the spatial distribution of nitrate and phosphate in Sempor Reservoir by field observation, water sampling, and laboratory analysis. The water was collected from 25 sampling points distributed at the outlet (close to the spillway), in the middle and the upstream of the reservoir, and around the fish pens (near the check dam). The results showed that nitrate was present on the reservoir water surface and at a depth of 1 meter at varying concentrations, i.e., <0.01-0.36 mg/L. The phosphate levels were <0.01-0.31 mg/L on the surface and <0.01-4.78 mg/L at a depth of 1 meter. The upstream had very high nitrate concentrations both on the surface and at a depth of 1 meter, while the outlet had very high content only at a depth of 1 meter. As for phosphate, very high concentrations were identified in the middle surface of the reservoir (near the pier) and at 1m depth around the fish pens.

Soil Organic Carbon Pool and its Storage in Arial Beel Wetland Soils of Bangladesh

The actual quantity of Soil Organic Carbon (SOC) stored in wetlands can only be estimated within a broad range of uncertainty. An accurate assessment of the size and distribution of the SOC storages in wetland resources is very difficult to obtain, therefore, the proposed research objective is to measure SOC storage and its pool on wetland soils of Arial beel in Bangladesh. Initial results of Arial beel soil profiles indicates SOC concentrations are high in surface soils ranges from 1.67 to 1.95% but its concentrations are decreasing with depth whereas SOC stock in kg C m-2 is increased with depth due to increse soil bulk density with depth. However, carbon in deeper layers may be more stable than that in surface soils due to difference in source, composition and environmental conditions. Soil organic C stored in the three different locations of wetlands soils to 1 m depth such as 16.47, 18.27 and 17.22 kg C m-2, respectively with an average of 17.32 kg C m-2. On the other hand, SOC stored in upland soils to 1m depth such as 11.24 kg C m-2, significantly less than the wetland soils, which indicates that wetland soils serve as a major source of SOC. However, this SOC act as a conditioner to enhance fertility status while combating with climatic extremes, not only that it is a vital component of soil with important effects on the functioning of terrestial ecosystems. For SOC pool, different extraction methods are used such as, highly labile fraction of SOC extracted with hot water (about 3-8% of toal SOC), water soluble fraction of SOC extracted with water (about 1% of total SOC), labile fraction is extracted using CaCl2 (about 1% of total SOC), moderately labile fraction extracted by pyrophosphate (about 4-10% of total SOC), polyaromatic SOC is extracted using toluene + methanol (trace amount of total SOC), microbial biomass C extracted by K2SO4 (about 2-5%) and the resistant fraction remaining after extraction. However, the SOC concentration is high in surface layer but with depth concentration decreases. In addition, soil bulk density and thickness values increase with depth, as a result deeper layers stored more carbon than surface layer in Arial beel soils. There is increasing evidence from the results that wetlands have an important and under-estimated role in carbon storage and its pool the regualation of greenhouse gas emission. Some types of wetlands play a particularly key role as C stores, these include forested wetlands and vegetated inter-tidal wetlands and hence, Sundarban mangrove forest and Tengarchar SOC stocks and pools measurement are an urgent issue for the Climate Change researchers and policy makers.

Spatio-seasonal patterns of demersal fish communities on the French Guiana Coast

Estuarine and coastal areas are often considered as hotspots due to their high diversity and ecological importance. However, communities living on those areas are often submitted to fishery and climate change pressures causing modifications on fish assemblages. French Guiana’s coastal shelf is characterised by warm waters with high turbidity and low salinity caused by the large river discharges from the Amazon and nearby estuaries. The high productivity of these areas supports fisheries and aquaculture activities. However, the structure and dynamics of coastal fish populations in French Guiana have seldom been studied. The aim of this study was to understand the effect of environmental conditions, as well as the influence of the coast and nearby estuaries on the spatio-seasonal variability of demersal fish communities living in shallow coastal waters (less than 20m depth). Data were collected from two fishing campaigns using a multi-filament drifting net during the rainy and dry season at 55 sampling stations along the coast. Results showed a high spatial patchiness and no clear seasonal pattern. Higher abundances and diversities were observed near estuaries where both marine and estuarine species were cohabitating. The high number of rare species and the aggregative behaviour recorded in this study suggest that those communities could be particularly affected by climate change, pollution and overfishing. In the light of increasing pressures expected in this area, new regulations and management programs should be developed to ensure food security and biodiversity conservation.

Potential groundwater recharge from deep drainage of irrigation water.

Knowledge of soil water dynamics in the deep vadose zone provides valuable information on the temporal and spatial variability of groundwater recharge. However, semi-arid climate can complicate how the input of water, such as irrigation, can contribute to potential groundwater recharge. This study assessed the recharge rates and their timing under irrigated cropland from a semi-arid region of northern Iran. A deep drainage (10m) experiment was performed and in situ soil water content was measured to analyze the soil water dynamics and model hydraulic parameters using HYSDRUS-1D. The best parameters selected from inverse parameter optimization were used to calibrate model and estimate the long-term (20-year) average groundwater recharge and the influence of the root zone, unsaturated zone and the time scale on the recharge processes. The simulated annual flux ranged from 24mm to 268mm (mean of 110mm) at 2-m depth and ranged between 26mm to 207mm (mean of 95mm) at the 10-m depth. High fluxes, observed between December and April, may be the result of greater precipitation combined with the irrigation return flow. The May-October period showed a gradual decrease in flux at the depth of 2m. At the depth of 10m, the flux showed some continuity (base flux) during the long-term recharge simulation. In total, 12.7% of the input water contributed to the recharge of the groundwater. The annual soil water fluxes were almost similar irrespective of depth below the root zone and the flux rates did not show any clear relation between the different components of the water budget at any depth. This approach improved our understanding of the recharge process in the deep vadose zone in a semiarid region and can help for the development of effective management of groundwater resources.

Comparative Analysis on Artificial Freezing Design Scheme of Vertical Underground Garage

Based on 7m length×7m weight×50m depth vertical underground garage of old residence communities in Shanghai China, the new article ground freezing (AGF) method— Box-frozen method was studied. The elastic theory calculation and numerical simulation showed that the thickness of straight (hq ) and bottom (hd ) frozen wall are 2.8m and 10m respectively, which can meet load bearing and water insulation requirements. Three artificial freezing design schemes and parameters were proposed according to different freezing hole layout, namely, 1) double row holes and cutting bottom holes;2) double row holes and leave bottom holes;3) single row holes and leave bottom holes. Evolution law of temperature field of different Box-frozen design schemes was checked by numerical simulation. The results showed that, during maintenance freezing period, both of double row holes and cutting bottom holes and single row holes and leave bottom holes schemes appear thaw phenomenon at bottom of frozen wall while double row holes and leave bottom holes stops thaw tendency basically. Three Schemes are compared in four aspects including construction period, cost, excavation difficulty and risks, which prove that double row holes and leave bottom holes scheme are a most suitable article ground freezing method due to less construction period and low risk.

Observation system simulation experiments using an ensemble-based method in the northeastern South China Sea

An ensemble-based method for the observation system simulation experiment (OSSE) is employed to design optimal observation stations and assess the present observation stations in the northeastern South China Sea (SCS). We employed the 20-year (1992–2012) sea surface height (SSH) data to design an array to monitor the intraseasonal to interannual variability. The results show that the most key region was found located at the northwest of Luzon Island (LI) where the energetic Luzon cyclonic gyre (LCG) occurs; other key regions include the edge of the LCG, the northwest of the Luzon Strait (LS), and the southwest of Taiwan, China. By contrast, we found that the present observation stations might oversample at the northwest of the LS and undersample at the northwest of LI. In addition, the optimal stations perform better in a larger area than the present stations. In vertical direction, the key layer is located within the upper 200-m depth, of which the surface and subsurface layers are most valuable to the observing system.

ANALISIS STABILITAS TUBUH BENDUNGAN PADA BENDUNGAN UTAMA PROYEK WADUK BENDO PONOROGO

The work of embankment in the main dam with an upright core consists of 5 pile zones: the core, filter, random, rock, and rip-rap. There was difference in planning and implementation of embankment filling. Random and rock used quarry Bondrang in planning but blasting upstream of the excavated material was used in implementation. This difference is because there are social problems with the community surrounding the Bondrang quarry. The purpose of this thesis is to repair the dam foundation, to find out the seepage discharge, to analyze the possibility of piping, to determine the safety factor of slope stability in the dam, and to determine RAB Maindam of Bendo Dam Project Ponorogo. The required data were of the geologic of the dam foundation, embankment materials, cross-sectional images of the dam body, and dam technical. Repairing the foundation using 3 methods : curtain grouting, consolidated grouting and blanket grouting; and for seepage calculations using the Cassagrande formula; to calculate safety figures using the Fellenius method and use the Geo-Studio 2012 application, the Seep / W program to find out the seepage discharge and the Geo-slope program to find out slope stability in maindam. The analysis resulted in 3 methods of repairing dam: curtain grouting with a depth of 39.83m, consolidated grouting with a depth of 5m, and blanket grouting with a depth of 15m; seepage discharge capacity &lt;1% passing water average meaning safe; velocity seepage (7,3816 x 10-7m/sec) &lt; velocity critical (0,004017m/sec) and 11,97 &gt; 4 meaning safe for piping; &gt;1.5 slope stability in various conditions without earthquake load meaning safe; 1.2 slope stability in various conditions with earthquake load meaning safe; the estimated cost IDR290,388,884,070.62 for main dam

Eocene-Oligocene succession at Kıyıköy (Midye) on the Black Sea coast in Thrace

A belt of Upper Eocene-Lower Oligocene marine sedimentary rocks extends from Kiyikoy on the Black Sea coast to Pinarhisar in the Thrace Basin, suggesting a marine connection between the Black Sea and the Thrace Basin during this period. The Cenozoic succession of this marine corridor was studied in the vicinity of Kiyikoy along two measured stratigraphic sections. The sequence lies unconformably over metamorphic basement rocks and consists of ~75 m of bioclastic limestone and sandstone of the Sogucak Formation, overlain by ~40 m of limestone, marl, mudstone, sandstone, and acidic tuff, which are assigned to the newly defined Servez Formation. Larger benthic foraminifera indicate that the lower part of the succession is Late Eocene in age, and nannoplankton from the upper part of the succession suggest an Early Oligocene age; these age determinations are also supported by the Sr-isotope data. A U-Pb age from zircons from a tuff bed is 33.9 ± 0.4 Ma, which falls on the Eocene-Oligocene boundary. The Kiyikoy Upper Eocene- Lower Oligocene sequence was deposited in shallow marine conditions below 50-m water depth. The depositional setting, as well as the relatively reduced thickness of the sequence, shows that any marine connection between the Black Sea and the Thrace Basin along the Kiyikoy-Pinarhisar corridor was not significant. The Late Eocene-Early Oligocene marine connection between the Black Sea and the Thrace Basin occurred along the Catalca gap southeast of Kiyikoy. In the Catalca gap the Upper Eocene-Lower Oligocene sequence is much thicker (350 m) and was deposited at much greater water depth.