Loss Of Sand Research Articles

Mechanism of Sand Loss into Submarine Canyon Offshore of Aramata Region of Shimoni-ikawa Coast

Several submarine canyons develop offshore of the Aramata region of the Shimoni-ikawa coast in Toyama Bay. The Kurobe River flows into the sea immediately east of this area, and a large amount of sediment has been supplied to this area as a source of westward longshore sand transport. However, after the construction of the detached breakwaters, offshore sand transport was accelerated and beach erosion occurred downcoast. In this study, aerial photographs and bathymetric survey data were analyzed and then, the mechanism of this offshore sand transport was investigated using the BG model proposed by Serizawa et al. (2006).

A Global Sand Budget—A Discussion of Sand Generation, Use and Destruction. Are We Running Out of Sand?

Recent articles on soil erosion sound the alarm regarding the large amount soil that is being lost due to modern agricultural practices, and there is a general concern that we may be destroying our sand and soil resources at rates that greatly exceed generation and preservation rates. There is also a general concern in the sand and aggregate industry as to whether sand is a renewable natural resource. The paper is unique and important to soil science as well as geology because it pulls together data from diverse sources in an attempt to summarize global rates of sand and soil generation from parent material, rates of sand consumption by humans, and rates of sand loss to humans through erosion and transportation to the oceans. While there is considerable literature on rates of soil erosion, there is remarkably little literature on rates of sand or soil generation from parent materials. Where rate numbers were found they were commonly local, and not global. They were commonly highly variable, and many conversions were required to put them in common, global units. Through a number of assumptions and calculations, the following conclusions have been made for global sand rates. (1) Sand is being generated from primordial granites at rates estimated at 1.6 billion tons/year. (2) Sand is being generated from soils at rates that range between 0.06 and 450 billion tons/year globally with an average of the most reasonable sources at 5.0 billion tons/year. (3) Sand today, through erosion and natural causes, is lost to the oceans at rates estimated at 4.8 billion tons/year. (4) Modern erosion rates are considered to be an order of magnitude greater than pre-human erosion rates, or about 0.5 billion tons/year. (5) Construction grade sand is currently mined at approximately 4.5 billion tons/year and industrial grade sand is consumed at about 0.2 billion tons/year for a total human usage estimated at 4.7 billion tons/year. Thus, total sand consumption by humans is slightly less than global generation rates, and an argument can be made that sand is a renewable natural resource. However, if modern rates of erosion and loss to the oceans are considered, then we are losing considerable ground with regard to total sand and soil availability.

Damage to Seisho Bypass due to Storm Waves During Typhoon 0709

Some 1.1 km of the Seisho Bypass along the Seisho coast was severely damaged on September 7, 2007, due to Typhoon 0709 storm waves, closing the road to traffic for emergency repairs. Damage to the highway, caused primarily through wave impact and secondarily by long-term shoreline recession due to decreased fluvial sand supply from the Sakawa River and sand loss into a submarine canyon, was investigated through field observations. A factor contributing further to shoreline recession was the obstruction of eastward longshore sand transport by the Ninomiya fishing port breakwater. Storm waves hit the coastline counterclockwise to normal to the shoreline, causing offshore and westward longshore sand transport with part of the sand transported by the longshore sand transport flowing into the submarine canyon, causing a net sand loss.

Fluidized sand biofilters used to remove ammonia, biochemical oxygen demand, total coliform bacteria, and suspended solids from an intensive aquaculture effluent

Effluents from aquaculture facilities must be effectively managed to remove dissolved wastes and suspended solids that can pollute receiving bodies of water. High volume, dilute flows leaving settling or filtration units can appear pristine, but still contain dissolved wastes. Effective technologies are needed to treat high volume effluents from intensive fish farms. The objective of this study was to evaluate fluidized sand biofilters as a treatment option for removing carbonaceous biochemical oxygen demand (cBOD5), total-ammonia-nitrogen (TAN), total phosphorous, total suspended solids (TSS), and total coliform bacteria from high volume intensive aquaculture effluents. Treatment across three full-scale CycloBio® fluidized sand biofilters was evaluated using two sand sizes, i.e., an effective size (D10) of 0.11-mm and 0.19-mm sand that were each expanded approximately 60% at a superficial velocity of 0.31cm/s and 0.64cm/s, respectively. Two bed management techniques were also evaluated: (1) siphoning from the top portion of the bed and (2) a biofilm shearing method in which a submersible pump was used to strip and release excess biofilm as it accumulated at the top of the expanded bed. Greater removal of cBOD5, TAN, and nitrite, and greater dissolved oxygen consumption across the biofilter correlated with the 0.11-mm sand. Additionally, improvements in removal of cBOD5, TAN, and nitrite, and greater dissolved oxygen consumption across the biofilter were measured when the biofilm shearing method was used to manage bed growth compared to siphoning. The biofilm shearing method was also more effective in controlling bed growth, resulted in less sand loss, and required substantially less labor than siphoning which was a large contrast from the labor required using the bed siphoning and sand replacement technique. The fluidized-sand biofilters removed 66–82% of the cBOD5 each pass and 86–88% of the TAN when bed growth was controlled using biofilm shearing. Outlet cBOD5 and TAN concentrations were reduced to 1.7±0.4mg/L and 0.11±0.04mg/L, respectively and outlet nitrite was 0.10±0.02mg/L when using biofilm shearing. Total phosphorous removal efficiency was 15–41% across the biofilters, and TSS removal was inconsistent but was achieved at inlet concentrations above 10mg/L for both bed management techniques. Results indicate that full-scale fluidized sand biofilters can effectively treat high volume, dilute aquaculture effluents.

Cumulative Losses of Sand to the California Coast by Dam Impoundment

Abstract California beaches depend on rivers for the majority of their sand supply, but coastal dams, which prevent sand from getting to beaches and nourishing them naturally, have significantly reduced this supply. Cumulative sand impoundment volumes for each littoral cell provide insight into which littoral cells have been impacted by human activities and where there may be a potential need to augment the littoral budget. Suspended sediment rating curves were created for the 21 major coastal streams in the state to estimate present-day sand fluxes based on relationships between suspended load and bed load. We then compared the postdam sand fluxes to estimated sand fluxes under predam conditions to determine the effects that dams have had on fluvial sand delivery to the coast. The cumulative sand impounded by California's 66 major coastal dams was then calculated on a littoral cell basis. Under predam conditions, California rivers delivered an average of about 10,000,000 m3/y of sand to the coast, but th...

Sand Budget Analysis Considering Changes in Grain Size-an Example of Shonan Coast

On the basis of bathymetric survey data, aerial photographs and sampling data of seabed materials, sand budget analysis considering changes in grain size was carried out, taking the Shonan coast as an example. A diagram showing sand budget was proposed, in which longshore sand transport, rate of windblown sand, grain sizes not only near the shoreline zone, but also in the offshore zone are shown. The loss and input of sand across the shoreline due to windblown sand and dredging in the ports are also summarized. This diagram can be effectively used for the coastal management of the coast.

Application of Model for Predicting both Bathymetric and Grain Size Changes to Shonan Coast

A model for predicting both topographic and grain size changes proposed by Kumada et al. was applied to the Shonan coast, facing Sagami Bay and with a stretch of 10 km. The model was applied to the entire littoral cell extending from the Sagami River mouth to Enoshima Island, and the wave diffraction effect of all the structures along and off the coastline, loss of windblown sand and various structures were taken into account. Predicted results of bathymetric and grain size changes were in good agreement with measured values. This model is effective for adaptive management of the beach restoration in terms of selecting appropriate grain size and the amount of beach nourishment.

西湘バイパスの被災原因の検討

The Seisho-bypass highway runs along the Seisho coast facing the Sagami Bay. On September 6, Typhoon 0709 attacked this coast with rough waves, and the road of this highway was severely damaged over 1.1km length, resulting in full traffic stoppage. During this typhoon, maximum significant wave height reached 6m with a wave period of 14s. Damages of the road were investigated through the field observation. Strong waves attacked the coastline from the Southeast, which is in contrast to the ordinary wave direction of the Southwest. Due to this oblique wave incidence, westward longshore sand transport was developed. Along this coast, the submarine canyons develop at several locations, and part of sand transported by longshore sand transport is considered to be flowed out of the submarine canyons, causing net loss of sand.

Model for Predicting Evolution of Ebb Tidal Delta and Measure for Preventing Offshore Sand Loss

A model for predicting the evolution of an ebb tidal delta was developed based on the BG model, which was proposed by the present authors using the Bagnold concept of the equilibrium slope. Bathymetric changes around the inlet of Imakiri-guchi during 1978 and 2005 were quantitatively analyzed to investigate the evolution of the ebb tidal delta and sand accumulation offshore of the inlet. The model was applied to this inlet. The predicted bathymetric changes were in good agreement with the measured. Measures for preventing the offshore sand loss were also considered using the model.

Sand Transport around North End of Shimizu Coast and Field Observation of Refilling Process after Foreshore Excavation

A submarine canyon develops around the north end of the Shimizu coast, and offshore sand loss into the submarine canyon through the steep slope has occurred. The bathymetric survey data were analyzed, and the rate of offshore sand transport was evaluated to be 160 m3/m/yr on the 0.4-km-long coastline. The foreshore excavation was experimentally carried out to investigate the capability of sand recycling from the tip of the sand spit. The rate of refilling was found to be 35m3/day in the test area.

Failure Analysis of a Bridge Embankment with Cracked Approach Slabs and Leaking Sand

This paper describes a successful failure analysis to determine the causes of loss of backfill sand from a mechanically stabilized earth (MSE) wall, and cracks on the concrete approach slabs on top of it. The Texas Department of Transportation was concerned that the cracks on the approach slabs may be related to the excessive loss of backfill from behind the MSE walls, and that the embankment structure may be unsafe due to potential voids under the concrete slab. Several cubic meters of sugar sand had washed out of the wall and deposited adjacent to the paneled walls. A series of destructive and nondestructive tests were carried out to determine the causes of the problems. It was found that the cracking of the approach slab and the loss of backfill were unrelated. Suggestions for resolving both problems were made based on this study.

Analyses on Erosion of Kashima Coast due to 2006 Autumn Storm Event

A strong low-pressure system traveled along Japanese Main Island in October 2006. High waves and storm surge attacked Kashima Coast resulting huge erosion over the area. This study analyzes sand loss in sub-aerial zone of southern part of the coast, a stretch of 16 km from Kashima Port to Tone River, using airborne laser data measured in October 2005 and November 2006, and X-band radar images captured during the storm. Longshore distribution of cross sectional change has been estimated from the laser data. Eroded volume of sub-aerial zone was estimated as 600, 000 m3. Pattern of erosion was controlled by headlands in the southern section, and by drainages in the northern section. Shoreline position during the storm has been digitized from radar images with locations of scarps read from aerial imagery.

Effects of beach erosion on abundance and distribution of toheroa (Paphies ventricosa) at Bluecliffs Beach, Southland, New Zealand

Data on abundance, distribution, and size structure of toheroa (Paphies ventricosa) on Bluecliffs Beach, Southland, New Zealand from 42 surveys (1966 to 2005) are presented. Toheroa abundance declined from over 2 million adults in the mid 1960s to c. 80000 by 1990 and since then has remained low but relatively stable. The decline mirrors that of other toheroa populations throughout New Zealand. Recent recruitment was highly variable but low compared with historical levels in the 1960s. Length frequency distributions are characteristically bimodal with a strong adult mode and a juvenile mode of variable strength, with relatively few toheroa of intermediate size. The distribution is related to mortality and growth characteristics of Bluecliffs Beach toheroa. Spatial distribution of adult toheroa has progressively changed over the last 40 years—historical distribution included the entire beach and toheroa were most dense just east of the Rowallan Burn. Since 1997, they have been aggregated into one large bed just west of the Rowallan Burn. Toheroa showed intertidal size zonation with small juveniles near high water and larger toheroa near mid to low water. Beach profile surveys were carried out in 1997, 2001, and 2005 to assess the dynamics of beach geomorphology and erosion. The surveys indicated a net loss of sand from the beach between 1997 and 2005, exposing underlying gravel and cobble substrates, and a general erosion of the vegetated dunes. Aerial photos from 1947 reveal that Bluecliffs Beach was homogeneous sand substrate—significant erosion and loss of sand began in the mid 1980s and only c. 54% of the beach surface is now fine/coarse sand. Our results indicate that distribution and abundance of toheroa on Bluecliffs Beach is related to the amount and distribution of sand on the beach. If the erosion continues with loss of sand habitat, the toheroa population may be at risk of collapsing.

Are inlets responsible for the morphological degradation of Venice Lagoon?

Through the centuries, Venice Lagoon has undergone morphological changes that can be attributed to both natural events and human actions. The lagoon has progressively deepened, and it is claimed to lose roughly one million cubic meters of sediments each year. In the ongoing debate concerning the possible means to counteract this morphodynamic degradation, inlet geometry is considered a major factor controlling the exchange of sediments. Our aim is to explore the causes of this loss. We focus first on sand, as this is the type of sediment present on the bottom of the near‐inlet regions. We employ a simple model of the inlet hydrodynamics to estimate the net exchange of sand associated with the sequence of tidal events recorded for several years. Results suggest that in the absence of an excess supply from the sea, the yearly loss of sand through Venice inlets is an order of magnitude smaller than the total sediment loss usually claimed. We then show that this estimate is only slightly affected by the sand supply from wave resuspension in the far field whose effect is simply to store sediments in the near‐inlet region. We finally argue that most of the sediment loss is wash load carried by the ebb currents overloaded by very fine sediments resuspended by wind in the inner lagoon and unable to settle within the channel network.

Shoreline accretion and sand transport at groynes inside the Port of Richards Bay

The south-western shoreline along the entrance channel inside the Port of Richards Bay has experienced continued erosion. Four groynes were constructed to stabilise the shoreline. Monitoring of shoreline evolution provided valuable data on the accretion adjacent to two of the groynes and on the sediment transport rates at these groynes. Tides, beach slopes, winds, wave climate, current regime, and sand grain sizes were documented. The one site is “moderately protected” from wave action while the other is “protected” according to the Wiegel [Wiegel, R. L. (1964). Oceanographical engineering. Prentice Hall, Inc., Englewood Cliffs, NJ.] classification. The shoreline accreted progressively at the two groynes at 0.065 m/day and 0.021 m/day respectively. The shorelines accreted right up to the most seaward extremity of the groynes. Equilibrium shorelines were reached within about 3.5 years to 4 years, which compare well with other sites around the world. The mean wave incidence angle is large and was found to be about 22°. The median sand grain sizes were 0.33 mm and 0.37 mm. The groynes acted as total traps, the beach surveys were extended to an adequate depth, and cross-shore sediment transport did not cause appreciable net sand losses into the entrance channel. The net longshore transport rate along the study area, which is north-westbound, is only slightly lower than the gross longshore transport. The actual net longshore transport rates are 18 000 m 3/year and 4 600 m 3/year respectively at the two groynes. A rocky area limits the availability of sand at one groyne. There is fair agreement between the predicted and measured longshore transport rates at the other groyne.

Field evidence for surface-wave-induced instability of sand dunes

Field studies of barchans--crescent-shaped dunes that propagate over solid ground under conditions of unidirectional wind--have long focused on the investigation of an equilibrium between sand transport by wind and the control of air flow by dune topography, which are thought to control dune morphology and kinematics. Because of the long timescale involved, however, the underlying dynamic processes responsible for the evolution of dune fields remain poorly understood. Here we combine data from a three-year field study in the Moroccan Sahara with a model study to show that barchans are fundamentally unstable and do not necessarily behave like stable solitary waves, as suggested previously. We find that dune collisions and changes in wind direction destabilize the dunes and generate surface waves on the barchans. Because the resulting surface waves propagate at a higher speed than the dunes themselves, they can produce a series of new barchans of elementary size by breaking the horns of large dunes. The creation of these new dunes provides a mechanism for sand loss that prevents dune fields from merging into a single giant dune and therefore plays a fundamental role in the control of size selection and the development of dune patterns.

A review of inlet bypassing solutions with nomographs

Bypassing of the coastal sediment at inlets is required to prevent downdrift erosion or the filling in of navigation channels. When coastal structures such as jetties or terminal groins are placed along the inlet boundaries, bypassing is reduced but not eliminated. Bypassing solutions such as Pelnard-Considere (1956) [Pelnard-Considere, R., 1956. Essai de Theorie de l'Evolution des Forms de Rivages en Plage de Sable et de Galets, Fourth Journess de l'Hydralique, les energies de la Mer, Question III, Rapport No. 1, pp. 289–298.] are known although the effect of existing background erosion on such bypassing is not so well known. The occurrence of existing erosion due to offshore sand loss complicates the bypassing situation. The following note reviews existing analytical bypassing solutions and presents a solution and nomograms for solving a bypassed amount when existing erosion occurs along a shoreline and the sand which bypasses the updrift structure is assumed to reach the downdrift shoreline without being trapped in shoals or inlet channel.

Spatial trends in the geochemical composition of sediments in the Panuco River discharge area, Gulf of Mexico.

Major and trace elements, organic matter, carbonates, loss of ignition, grain size, gravel, sand, silt, clay, and qualitative mineralogical composition were determined on surficial marine sediments sampled during the stormy (February), dry (May), and rainy (September) seasons in the coastal area adjacent to Panuco River discharges into the Gulf of Mexico. The sediments supplied by the river move in a north-east direction, and are deposited in the north-east extreme of the studied area. Terrigenous sediments show a strong association of Al2O3 with Fe2O3, Na2O, K2O, P2O5, Rb, Cu, Zn, organic matter, clay, and grain size (Mz). Mineralogical analysis shows that they are formed by quartz, kaolinite, montmorillonite, illite-montmorillonite and biotite. The highest metal concentration of Cu (25 mg/kg), Zn (155 mg/kg), Pb (50 mg/kg) and organic matter (1.26%) was observed in the sampling points located very close to the river mouth. A statistical analysis was done with the information contained in the variables. Five significant factors explain 77% of the total variance: factor 1 is due to sediments from a terrigenous source, factor 2 corresponds to sediments from a biogenous source, factor 3 is associated to sediments with heavy minerals, factor 4 is due to Co concentration, and factor 5 is due to Ni concentration. The sediments supplied from the river had a short-term local impact on the sediment distribution, as observed by the carbonate and heavy mineral concentration of the sediments.

リーフ海岸における養浜工の設計・施工および養浜後の海浜応答

Extensive beach nourishment was carried out at Sanur and Nusa Dua beaches in Bali, Indonesia to recover natural sandy beach on the reef coasts. Planning and construction of beach nourishment were described in detail. 3.0*105m3 and 3.5*105m3 of sand were nourished at Sanur and Nusa Dua beaches, respectively. Monitoring surveys have been conducted to investigate stability of nourished beaches. Due to the change of the shoreline and longitudinal profiles, artificial beaches which were separated by groins and headlands reached in a stable condition within a few months. Sand loss was negligibly small.

Impacts of Dredging on Shoreline Change

Nearshore dredging for construction aggregate or beach nourishment can result in a perturbation of natural littoral processes, changes in wave transformation patterns, and a net loss of sand from the littoral system. A method is described for estimating both direct and indirect effects of dredging on shoreline change. The direct effect results from infilling of the dredged pit via cross-shore sediment transport and is addressed statistically, assuming that the beach profile is in some arbitrary equilibrium shape. The indirect effect arises from project-induced wave transformation, which alters longshore sediment transport patterns, and is described using both spectral and monochromatic, numerical wave transformation models to provide input to a one-line model for shoreline change. Infilling of the pit is neglected when estimating the indirect effect, providing a worst-case estimate of the indirect effect. The methodology is applied to a site on the Turkish Black Sea coast, using hindcast wave data. The influences of pit location and geometry are investigated systematically, and recommendations regarding optimum pit dimensions and locations are made.