Sediment Grain Size Distribution Research Articles

Changes in benthic invertebrate communities of central Appalachian streams attributed to hemlock woody adelgid invasion

Eastern hemlock trees (Tsuga canadensis [L.] Carr.) often dominate riparian vegetation of central Appalachian headwater streams, and the invasive hemlock woolly adelgid (Adelges tsugae Annand; HWA) has decimated hemlock stands in this region. Although research concerning HWA impacts on soil, hydrology, and forest structure is emerging, associated changes in stream structure and function are not as well documented. We quantified HWA-invasion effects on benthic macroinvertebrate communities in 21 headwater streams across Ohio, West Virginia, and Virginia (USA) representing unimpacted, moderate invasion, and severe invasion, respectively. We observed differences in benthic macroinvertebrate community composition; severely invaded sites exhibited the highest diversity, whereas moderate sites had the lowest diversity. The composition of macroinvertebrate functional feeding groups exhibited shifts as well. For example, the relative abundance of herbivorous invertebrates increased from 4% (± 3%) at unimpacted sites to 23% (± 14%) at severely impacted sites. Changes in macroinvertebrate density, diversity, and functional-group composition were associated with sediment grainsize distribution (proportion bedrock and D84), large-wood characteristics (volume and density), and nutrient concentrations (PO4 and NH4). Our results suggest that in-stream physical and chemical alterations associated with HWA-invasion and subsequent hemlock decline are associated with changes in stream invertebrate diversity and trophic relationships. We demonstrate how a pervasive terrestrial invader can influence in-stream biotic communities.

Holocene environmental changes in Red River delta, Vietnam as inferred from the stable carbon isotopes and C/N ratios

The present study applied stable carbon isotopes, C/N ratios, and sedimentological indicators to reconstruct environmental changes during Holocene and to test the hypothesis that $$\updelta ^{13}\hbox {C}$$ and C/N ratios are accurate proxies of sea level change in the Red River delta (RRD), Vietnam. A 36 m long sediment core was mechanically drilled in the wave-dominated region of the RRD. The covariation of lithological characteristics, sediment grain-size distribution and geochemical proxies (LOI, TOC, C/N, $$\updelta ^{13}\hbox {C}$$ ) suggested that the sediment core could be divided into six depositional environments, consisting of sub- and inter-tidal flats (formed before 8860 cal. year BP), shelf-prodelta, delta front slope (formed from 8860 to 2290 cal. year BP), delta front platform, tidal flat, and flood plain (from 2290 to 0 cal. year BP). Covariation of $$\updelta ^{13}\hbox {C}$$ and C/N ratios in the sediment core allowed for tracing the origin of sedimentary organic carbon, which shifted from the dominance of mangroves and C3 plants at the sub- and inter-tidal flats to marine phytoplankton at the shelf-prodelta and delta front slope. The sedimentary sources of the delta front platform, tidal flat and flood plain were a mixture of phytoplankton and C3 plants, with the later source being dominant.

Hydrodynamics and Sediment Mobility Processes Over a Degraded Senile Coral Reef

AbstractCoral reefs can influence hydrodynamics and morphodynamics by dissipating and refracting incident wave energy, modifying circulation patterns, and altering sediment transport pathways. In this study, the sediment and hydrodynamic response of a senile (dead) barrier reef (Crocker Reef, located in the upper portion of the Florida Reef Tract) to storms and quiescent conditions was evaluated using field observations and the Coupled Ocean‐Atmosphere‐Wave‐Sediment Transport model. Waves, circulation, and resultant sediment mobility were modeled across different reef zones. Sediment mobility during quiescent periods and the passage of far‐field storms are driven by nonbreaking waves and, to a lesser degree, regional circulation. Spatial variability in these processes produces the present‐day distribution of sediment grain size at Crocker Reef, wherein finer‐grain material along a shallow central ridge is frequently mobilized (43% to 62% of the time), winnowed away, and deposited along the lower‐energy flanks and in the fore reef where sand mobility occurs less frequently (32% to 43% and 1% to 22% of the time, respectively). Analysis of wave conditions for the period of 2006–2014 supports that wave heights rarely exceed the threshold for breaking (0.1% and 0.3% at the reef crest and at the reef flat, respectively), predominantly during the passage of tropical storms. There is a shift to a wave‐breaking regime during near‐field storms, creating the potential for mobilization of larger material and enhanced reef degradation. Sediment mobility can be enhanced due to wave skewness or the generation of free infragravity waves during periods of depth‐induced wave breaking.

Geochemistry and grain size distribution of surface sediments of a large semi-enclosed lagoon connected to the western Bay of Bengal

Batticaloa is a large (135.5 km2), semi-enclosed, micro-tidal lagoon that formed by barrier deposits in eastern Sri Lanka and has a unique geographic position due to its tropical monsoonal climate and absence of tectonics. The recent soft bottom sediments of Batticaloa lagoon were studied on the basis of geochemistry and grain size distribution in order to interpret their characteristics and provenance. Poor to moderately sorted medium sands are the dominant sedimentary deposits for the lagoon; therefore, a medium energy condition is suggested for sediment deposition. The average silt and clay fraction of the lagoon sediments is less than 3%, indicating medium or high energy flows. Coarser deposits are restricted to channel and lagoon mouths. The scatter plots of Nb, Zr, Cr and Sc vs. Th and Cr/V vs. Y/Ni show a felsic provenance for the sediments. The normalized diagrams of major element oxides and trace elements for the regional rocks (Vijayan Complex of Sri Lanka) indicate high country rock influence for the sedimentation for the semi-enclosed setting. The enrichment and distribution of Zr, Th, Nb, Cr and TiO2 suggest the possibility of mineral sands that are fractionated with hydrodynamic setting of the lagoon.

Filter Or Conveyor? Establishing Relationships Between Clinoform Rollover Trajectory, Sedimentary Process Regime, and Grain Character Within Intrashelf Clinothems, Offshore New Jersey, U.S.A.

Clinoform geometries and trajectories are widely used to predict the spatial and temporal evolution of sand distribution, but most analytical approaches underplay the significance of topset and shelf process regime in determining how and when sediment is conveyed downdip or stored on the continental shelf. We present an integrated study of clinoform rollover trajectory and detailed grain character analysis to assess the role of topset process regime in determining sand distribution and sediment character across clinothems. This study targets the topset, foreset, and bottomset deposits of four successive Miocene intrashelf clinothem sequences, which represent deposition under either river-dominated or wave-dominated conditions. Seismic reflection data was combined with core analysis and grain character data derived from 664 samples collected from three cored research boreholes. In river-dominated clinothems, the transfer of coarse-grained sediment occurs under both rising and flat-to-falling clinoform rollover trajectories, suggesting that process regime is more important in determining sediment delivery than clinoform trajectory; river-dominated systems are effective conveyors of sediment into deeper water. Wave-dominated clinothems deposited exclusively under rising clinoform rollover trajectories largely retain sand within topset and foreset deposits; wave-dominated systems are effective sediment filters. Notably, deposition under either river- or wave-dominated topset process regimes results in quantifiable differences in grain character attributes along clinoform profiles. Sediments in river-dominated systems are coarser, less well-rounded, and more poorly sorted, and show greater intersequence and intrasequence variability than those in wave-dominated systems; prediction of sediment character is more challenging in river-dominated systems. This study highlights the need for caution when attempting to predict downdip sand distribution from clinoform trajectory alone, and provides a novel perspective into downdip grain character profiles under end-member topset process regime conditions. The results of this study can be used to better constrain sediment grain-size and grain-shape distributions in process-based forward models, and have widespread applications in prediction of reservoir quality in both frontier and mature hydrocarbon basins.

Efectos de las extracciones de áridos sobre el transporte de sedimentos en suspensión en ríos de montaña (alto río Cinca, Pirineo Central)

Este artículo analiza los efectos de una extracción de áridos sobre el transporte de sedimento en suspensión en un tramo del alto río Cinca (Pirineo Central). Para ello se monitorizaron cinco secciones a lo largo de un tramo de 5 kilómetros para obtener datos de caudal y transporte de sedimentos así como las granulometrías de los sedimentos finos. De manera específica, se han obtenido muestras en una sección de referencia aguas arriba del área de actuación y cuatro secciones, a 0, 200, 500, y 1500 m, aguas abajo de ésta. Los resultados confirman un efecto de las extracciones de áridos sobre el transporte de sólidos en suspensión, alcanzándose concentraciones aguas abajo de la extracción un orden de magnitud mayor que en la sección de referencia. Las CSS medias obtenidas durante los días de estudio son similares a los valores registrados durante crecidas, llegándose a alcanzar concentraciones máximas de casi 6 g/l. La carga sólida varía entre 2,2 y 17 Mg/día entre secciones, valores que incorporan también los efectos de los trabajos realizados en el cauce durante los días previos a la extracción. Las concentraciones observadas en la sección más alejada son similares a las medidas en la sección de referencia, hecho que indica que la mayor parte del material movilizado por la extracción quedó sedimentado en los primeros centenares de metros. El tamaño de las partículas del sedimento removilizado y transportado como consecuencia de la extracción es mayor que el que se observa en condiciones naturales; no obstante, las partículas de mayor tamaño sedimentaron rápidamente, hecho que sugiere un lavado selectivo de los materiales transportados aguas abajo. Este estudio supone un primer paso para la comprensión de la dinámica del sedimento en ríos localmente afectados por actuaciones en el cauce y su influencia en la dinámica morfosedimentaria y la integridad bio-física del río.

Relationship between Grain Size Distribution and Radon Content in Surficial Sediments of Wadi Arar, Saudi Arabia

Relationship between Grain Size Distribution and Radon Content in Surficial Sediments of Wadi Arar, Saudi Arabia

Relationship between Grain Size Distribution and Radon Content in Surficial Sediments of Wadi Arar, Saudi Arabia

Surficial sediments with low radon content are desirable materials in construction applications. In this study, the relationship between grain size and radon content was investigated in sediments collected from seven sites in Wadi Arar, Saudi Arabia, with the intent of determining whether grain size analysis could be used for rapidly assessing the suitability of potential construction materials. Thirty-five samples were collected (five per site) and the grain size distribution was determined using sieves. Radon contents were measured on composite samples with a RAD7 radon detector. Among the sediment types (gravel, coarse sand, medium sand, fine sand, and silt and clay), the best linear correlations between grain size and radon contents were found for the coarse sand (negative slope, r=0.82) and fine sand (positive slope, r=0.78). Polynomial relationships were also tested. A fourth-degree polynomial equation effectively described the correlation between grain size and radon content (R2 = 0.933). As shown by this model, the highest correlations with radon contents were detected at grain sizes smaller than 2.0 mm. Thus, grain size may be useful for preliminary site assessment work.

Lithological controls on hillslope sediment supply: insights from landslide activity and grain size distributions

AbstractThe volumes, rates and grain size distributions of sediment supplied from hillslopes represent the initial input of sediment delivered from upland areas and propagated through sediment routing systems. Moreover, hillslope sediment supply has a significant impact on landscape response time to tectonic and climatic perturbations. However, there are very few detailed field studies characterizing hillslope sediment supply as a function of lithology and delivery process. Here, we present new empirical data from tectonically‐active areas in southern Italy that quantifies how lithology and rock strength control the landslide fluxes and grain size distributions supplied from hillslopes. Landslides are the major source of hillslope sediment supply in this area, and our inventory of ~2800 landslides reveals that landslide sediment flux is dominated by small, shallow landslides. We find that lithology and rock strength modulate the abundance of steep slopes and landslides, and the distribution of landslide sizes. Outcrop‐scale rock strength also controls the grain sizes supplied by bedrock weathering, and influences the degree of coarsening of landslide supply with respect to weathering supply. Finally, we show that hillslope sediment supply largely determines the grain sizes of fluvial export, from catchments and that catchments with greater long‐term landslide rates deliver coarser material. Therefore, our results demonstrate a dual control of lithology on hillslope sediment supply, by modulating both the sediment fluxes from landslides and the grain sizes supplied by hillslopes to the fluvial system. Copyright © 2017 John Wiley & Sons, Ltd.

Comparing grain size distribution of sediment and original soil under raindrop detachment and raindrop-induced and flow transport mechanism

ABSTRACTThe grain size distribution (GSD) of sediment in comparison with the original soil GSD is discussed under different slopes (5, 15 and 25%) and rainfall intensities (30, 60 and 90 mm h–1 with respective duration of 30, 15 and 10 min) but identical runoff (15 mm). The sediment quantification was carried out by raindrop-induced flow transport (RIFT) or/and transport by flow (FT) using a rainfall simulator and a 6 × 1 m2 erosion plot and a silt loam. The results show a high degree of enrichment for size classes of 2–4 and 4–8 μm and a high degree of depletion for size classes of >63 μm under different slopes and rainfall intensities. In addition, the results show that the experimental enrichment ratio (ER) for particle size <16 μm under different slopes and rainfall intensities was greater than 1, while the ER for particle size >32 μm was less than 1.

Temporal variations of bed load transport rate and the grain size distribution of non-uniform size sediment during a constant flow rates

Bedload transport rates at a point using both laboratory and field measurement vary with time, from almost zero to several folds of the mean rate. The need to carry out point measurements over a sufficiently long sampling period is very important to cover inconsistency in the transport rate during a short period of observation. In this experiment the bedload was collected at a slot type sediment trap with ten-minute intervals throughout the tests. The aim was to examine the behaviour of mixed grain size sediment transportation during constant flowrates. Two hydrographs were applied to quantify the transport mode changes caused by an increase in time length as the mixtures were continuously exposed to the flow. It shows that intense bed degradation process occurred within three hours of the tests as indicated by almost identical rates of bedload transport during this period and the diminishing rate in the remaining hours. This reflects that a stable bed was achieved after three hours in which the armouring process was believed to take place. The grain size distribution suggests that the proportion of fine mode was relatively stable and the modal grain size of this mode experienced a similar pattern throughout the tests whilst the coarse mode was inconsistent and varied periodically.

Identifying, characterizing and predicting spatial patterns of lacustrine groundwater discharge

Abstract. Lacustrine groundwater discharge (LGD) can significantly affect lake water balances and lake water quality. However, quantifying LGD and its spatial patterns is challenging because of the large spatial extent of the aquifer–lake interface and pronounced spatial variability. This is the first experimental study to specifically study these larger-scale patterns with sufficient spatial resolution to systematically investigate how landscape and local characteristics affect the spatial variability in LGD. We measured vertical temperature profiles around a 0.49 km2 lake in northeastern Germany with a needle thermistor, which has the advantage of allowing for rapid (manual) measurements and thus, when used in a survey, high spatial coverage and resolution. Groundwater inflow rates were then estimated using the heat transport equation. These near-shore temperature profiles were complemented with sediment temperature measurements with a fibre-optic cable along six transects from shoreline to shoreline and radon measurements of lake water samples to qualitatively identify LGD patterns in the offshore part of the lake. As the hydrogeology of the catchment is sufficiently homogeneous (sandy sediments of a glacial outwash plain; no bedrock control) to avoid patterns being dominated by geological discontinuities, we were able to test the common assumptions that spatial patterns of LGD are mainly controlled by sediment characteristics and the groundwater flow field. We also tested the assumption that topographic gradients can be used as a proxy for gradients of the groundwater flow field. Thanks to the extensive data set, these tests could be carried out in a nested design, considering both small- and large-scale variability in LGD. We found that LGD was concentrated in the near-shore area, but alongshore variability was high, with specific regions of higher rates and higher spatial variability. Median inflow rates were 44 L m−2 d−1 with maximum rates in certain locations going up to 169 L m−2 d−1. Offshore LGD was negligible except for two local hotspots on steep steps in the lake bed topography. Large-scale groundwater inflow patterns were correlated with topography and the groundwater flow field, whereas small-scale patterns correlated with grain size distributions of the lake sediment. These findings confirm results and assumptions of theoretical and modelling studies more systematically than was previously possible with coarser sampling designs. However, we also found that a significant fraction of the variance in LGD could not be explained by these controls alone and that additional processes need to be considered. While regression models using these controls as explanatory variables had limited power to predict LGD rates, the results nevertheless encourage the use of topographic indices and sediment heterogeneity as an aid for targeted campaigns in future studies of groundwater discharge to lakes.

Late Holocene shift towards enhanced oceanic variability in a high-Arctic Svalbard fjord (79°N) at 2500 cal. yr BP

Paleoclimate records are crucial for understanding current changes taking place in the Arctic, e.g., the amplified warming and associated changes in sea-ice cover. However, paleoclimate and -oceanographic reconstructions, especially from the high Arctic, are scarce. Here, we present a reconstruction of sea surface and paleoenvironmental conditions from a Holocene marine sediment core collected from a high-Arctic fjord, Isvika Bay, Nordauslandet, Svalbard (79°N). Our proxies include qualitative diatom assemblage data [focusing on the Marginal Ice Zone (MIZ) taxa], a quantitative diatom-based August sea surface temperature (aSST) reconstruction, sediment grain-size distribution, and ice-rafted debris (IRD) spanning the period from 4200 cal. yr BP to the Little Ice Age (LIA) at ca. 200 cal. yr BP. The results reveal cold and stable, glacier-proximal conditions for the beginning of the late Holocene (from 4200 to 2500 cal. yr BP). Then, at 2500 cal. yr BP, the environment shifted into distinctly more fluctuating conditions, where colder and warmer aSSTs alternated in a glacier-distal environment. During the latter part of the late Holocene, sea-ice cover was extensive, yet variable, negatively co-varying with aSST. Based on our diatom data, we observe a clear increase in the influence of Atlantic water in Isvika Bay during the last ca. 600 years.

The paleoenvironmental significance of spatial distributions of grain size in groundwater‐recharged lakes: A case study in the hinterland of the Badain Jaran Desert, northwest China

AbstractFor lakes in desert hinterlands that are not recharged by river runoff, sediment input solely comes from wind transport. While the processes of sediment transport and deposition in these lakes differ significantly from those with river discharge, the spatial distribution of sediment grain size in these groundwater‐recharged lakes remains largely unknown. Moreover, whether the grain size distribution in these lake sediments can be used as a proxy in the study of past climatic change and environmental evolution studies is unclear. In this study, five lakes with a range of surface areas that had no runoff recharge were selected from the hinterland of the Badain Jaran Desert of north‐western China, and a total of 108 samples of lake surface sediments were collected to examine the spatial distribution of grain size. Moreover, an end‐member‐modeling algorithm was used to calculate end members from all grain size measurements. Our results showed that both the median and mean grain sizes in the lake sediments decreased from the nearshore to the offshore, deep‐water zone. However, the lowest median and mean grain sizes were not found in the center of the lakes, in contrast to lakes recharged by surface runoff. The median grain size of sediment in the lake center was negatively correlated with lake level, and thus could help reveal lake evolution at low resolutions. Moreover, EM1 and EM2 were interpreted as wind transported sediment, and sediment perturbed by lake waves after wind transport, respectively. The modal grain size of EM1 varied slightly between lakes, while changes in the modal grain size of EM2 were related to lake area. Given the positive relationship found between EM2 content and lake level, changes in the EM2 content (%) can serve as a rough indicator of lake level fluctuations at low temporal resolutions. Copyright © 2017 John Wiley &amp; Sons, Ltd.

Hydrological changes in Shuangchi Lake, Hainan Island, tropical China, during the Little Ice Age

Hydrological changes in East Asia during the last millennium have been addressed by numerous earlier studies, but spatial characteristics and dynamics in precipitation variations during the Little Ice Age (LIA) remain unclear, perhaps especially due to the sparse coverage of high-resolution hydrological records from tropical and sub-tropical regions in East Asia. In this study, a sediment core was obtained from Shuangchi Lake in northern Hainan Island, tropical China, of which geochemical proxies including the ratios of Rb/Sr, Rb/K, Zr/Rb and Si/Ti were analyzed using an X-ray fluorescence (XRF) core scanner. Meanwhile, the grain size distribution of sediments was also determined. The results show that the Rb/Sr and Rb/K ratios decreased significantly during the LIA, whilst the Zr/Rb and Si/Ti ratios increased along with higher median grain size. The changes of these proxies likely suggest that precipitation was enhanced during the LIA in this region, and this was consistent with other hydrological records from tropical southern China. The synthesis of hydrological records from East Asia and the tropical Pacific suggest that the co-existence of a contracted Intertropical Convergence Zone (ITCZ) and strengthened Pacific Walker circulation (PWC) could contribute synchronously to the increased precipitation in the tropical region of southern China during the LIA.

Importance of measuring discharge and sediment transport in lesser tributaries when closing sediment budgets

Sediment budgets are an important tool for understanding how riverine ecosystems respond to perturbations. Changes in the quantity and grain size distribution of sediment within river systems affect the channel morphology and related habitat resources. It is therefore important for resource managers to know if a river reach is in a state of sediment accumulation, deficit or stasis. Many sediment-budget studies have estimated the sediment loads of ungaged tributaries using regional sediment-yield equations or other similar techniques. While these approaches may be valid in regions where rainfall and geology are uniform over large areas, use of sediment-yield equations may lead to poor estimations of loads in regions where rainfall events, contributing geology, and vegetation have large spatial and/or temporal variability.Previous estimates of the combined mean-annual sediment load of all ungaged tributaries to the Colorado River downstream from Glen Canyon Dam vary by over a factor of three; this range in estimated sediment loads has resulted in different researchers reaching opposite conclusions on the sign (accumulation or deficit) of the sediment budget for particular reaches of the Colorado River. To better evaluate the supply of fine sediment (sand, silt, and clay) from these tributaries to the Colorado River, eight gages were established on previously ungaged tributaries in Glen, Marble, and Grand canyons. Results from this sediment-monitoring network show that previous estimates of the annual sediment loads of these tributaries were too high and that the sediment budget for the Colorado River below Glen Canyon Dam is more negative than previously calculated by most researchers. As a result of locally intense rainfall events with footprints smaller than the receiving basin, floods from a single tributary in semi-arid regions can have large (≥10×) differences in sediment concentrations between equal magnitude flows. Because sediment loads do not necessarily correlate with drainage size, and may vary by two orders of magnitude on an annual basis, using techniques such as sediment-yield equations to estimate the sediment loads of ungaged tributaries may lead to large errors in sediment budgets.

Particle selection and feeding behaviour in two cirratulid polychaetes

Cirratulid polychaetes are abundant and diverse members of the benthic macrofauna and their particle collection mechanisms may strongly affect particle mixing and sediment grain size distribution in sediments. The feeding morphology differs in having a pair or many feeding tentacles and the ecological importance of both methods of food collection needs to be better investigated to understand their costs and benefits. Particle selection and feeding behaviour of a bitentaculate (Aphelochaeta honouliuli) and a multitentaculate species (Timarete hawaiensis) were comparatively observed. Feeding behaviour observations were done with individuals with or without feeding tentacles and exposed to three different size ranges of glass beads (0–20, 40–70 and 70–110 µm in diameter). Particle selection was tested for coated and uncoated glass beads of three different size ranges in 20 specimens of each species. Feeding behaviour was similar in both species and the methods of particle collection and ingestion are described. Individuals of T. hawaiensis, in which the feeding tentacles were removed, were observed collecting particles with the aid of branchiae. The multitentaculate species studied was more successful in collecting particles from greater foraging radii and at a faster rate than the bitentaculate species but the experimental design may have disfavoured the latter. Two-way ANOVA results showed that both bitentaculate and multitentaculate species significantly selected in favour of smaller particle sizes. Further studies about particle encounter, selection and ingestion are needed and may aid understanding of the phylogenetic relationships between the bitentaculate and multitentaculate cirratulids.

Effects of intensification of the Indian Summer Monsoon on northern Andaman Sea sediments during the past 700 years

Recent studies have revealed an intensification of the Indian Summer Monsoon (ISM) over the past 700 years, but its influence on the sediments in the northern Andaman Sea is unclear. To examine this influence, we used radiocarbon-dated sediment core StMY6, acquired 100 km offshore in the northern Andaman Sea from the Ayeyarwady River mouth, and obtained a 700-year-long record of the grain-size distribution and geochemistry of the sedimentary sequence. The ISM influences precipitation surrounding the Ayeyarwady River, and thus the river water and sediment discharges to the northern Andaman Sea near the river mouth in the Ayeyarwady River and the weathering intensity in the river catchment. Based on the system, we propose that higher sedimentation rates and larger modal grain size (the most abundant size in the grain-size distribution of sediments) and lower carbonate concentrations after about AD 1600 can be attributed to higher ISM intensity. Profiles of total organic carbon (TOC) content and carbon/nitrogen (C/N) ratios, however, did not show any trends after about AD 1600, which suggests that the ISM has had little influence on these proxies at this site.

SEDIMENT DISTRIBUTION ANALYSIS IN BALOHAN BAY, SABANG

&lt;em&gt;We investigated the sediment properties and distribution in Balohan Bay, which is located in southern Weh Island, Aceh Province. The aim of this research was to clarify the sediment distribution mechanism in the Balohan Bay using a statistical approach. Samples were collected on January 2016 using coring method. Sediment grain-size distribution from 14 stations was obtained using wet sieve analysis. A large amount of fine sand and very fine sand were found in Balohan Bay, as a result of several tributaries discharged in those areas. The sediment distribution in eastern stations showed an indication as a coarser size and a poorer sorted area, as they were adjacent to the steep cliff.&lt;/em&gt;

SEDIMENT DISTRIBUTION ANALYSIS IN BALOHAN BAY, SABANG

We investigated the sediment properties and distribution in Balohan Bay, which is located in southern Weh Island, Aceh Province. The aim of this research was to clarify the sediment distribution mechanism in the Balohan Bay using a statistical approach. Samples were collected on January 2016 using coring method. Sediment grain-size distribution from 14 stations was obtained using wet sieve analysis. A large amount of fine sand and very fine sand were found in Balohan Bay, as a result of several tributaries discharged in those areas. The sediment distribution in eastern stations showed an indication as a coarser size and a poorer sorted area, as they were adjacent to the steep cliff.