Sand Transport During Closure of Tidal Channels

1972 ◽  
Author(s):  
J.N. Svasek ◽  
J.H.J. Terwindt ◽  
A.W. Walther
Keyword(s):  
Sand Transport ◽  
Tidal Channels

GEOMORPHOLOGICAL ALTERATION OF A HEAVILY OILED SALTMARSH (ILE GRANDE, FRANCE) AS A RESULT OF MASSIVE CLEANUP

1981 ◽  
Vol 1981 (1) ◽  
pp. 347-351 ◽  
Author(s):  
J. H. Vandermeulen ◽  
B. F. N. Long ◽  
L. D'Ozouville
Keyword(s):  
Flow Characteristics ◽  
Sand Transport ◽  
Tidal Prism ◽  
Tidal Channels ◽  
Cross Sectional ◽  
Left Behind ◽  
Long Term Storage ◽  
Storage Reservoirs ◽  
Flow Through ◽  
Geomorphological Changes

ABSTRACT During massive cleanup of a heavily oiled saltmarsh, much of the surface sediment was removed to a depth of about 50 centimeters (cm), exposing in places the underlying granitic basement. This has resulted in a marked increase in the marsh cross-sectional area, in its tidal prism, and in the current velocities through the marsh. As a result, the marsh is undergoing increased erosion and invasion of sand from offshore stocks. Observations of sand transport 1 year after the cleanup, as well as the formation of megaripple and sheet-flow characteristics 2 years after the cleanup, indicate an increase in current velocities from a pre-spill average of 0.5 meters per second (m/s) to 1 m/s, and exceeding 1.7 m/s in the main channel of the marsh. A 2-year study of geomorphological changes in the marsh has shown that the normal pre-spill colonization rate of the marsh (28 to 90 cm/yr) has changed to a net erosion (6.5 to 17 m/yr). Increased current velocities have resulted in erosion of the exposed marsh surfaces and undercutting of the secondary and tertiary marsh tidal channels. Residual oil, left behind from the cleanup, is being trapped under sandbars. Pockets of such oil-permeated sand deposits represent potential long-term storage reservoirs available for later release. Marsh recovery to pre-spill state depends critically on the reduction of its tidal prism and of the current flow through the marsh. Based on the depositional rates for this marsh and others, this is expected to be a very slow process, unless perhaps it is enhanced by replanting saltmarsh vegetation in denuded areas.

scholarly journals Alignment of fluvio-tidal point bars in the middle McMurray Formation: implications for structural architecture of the Lower Cretaceous Athabasca Oil Sands Deposit, northern Alberta

2016 ◽  
Vol 53 (9) ◽  
pp. 896-930 ◽  
Author(s):  
Paul L. Broughton
Keyword(s):  
Oil Sands ◽  
Upper Devonian ◽  
Sand Transport ◽  
River Channels ◽  
Tidal Channels ◽  
Lower Estuary ◽  
Channel Network ◽  
Athabasca Oil Sands ◽  
Mcmurray Formation ◽  
Point Bars

The northern Athabasca Oil Sands Deposit accumulated on sub-Cretaceous structure partially configured by multistage pre-Cretaceous salt dissolutions in Prairie Evaporite (Middle Devonian) substrate that continued concurrent with deposition of McMurray Formation (Aptian) strata. Dissolution fronts only 250 m below advanced along NW- and NE-oriented fracture–fault lineaments that coalesced into larger salt removal areas. This structural grain was transmitted to the overlying dissected Upper Devonian karst topography draped by lower McMurray braided rivers along a lattice-like channel network. The dominant NW structural grain continued during middle McMurray deposition, with fluvial-estuarine point bars aligned along subparallel tidal channels. Regional salt removal fronts concurrent with middle McMurray deposition migrated north of the Bitumount Trough, resulting in the 200 km2 central collapse. The northern Athabasca Deposit area was configured as a funnel-shaped lower estuary structure consisting of aligned Upper Devonian – lower McMurray fault block terraces that stepped down northward into the central collapse. Sinuous river channels of the upper estuary, constrained along stable substrate of the main paleovalley, flowed northward onto the unstable floor of this funnel-form lower estuary. The main paleovalley fairway branched into multiple tens of kilometres long subparallel fluvio-estuarine tidal channels aligned parallel to the NW structural grain. Sand transport fairways cascaded over the step-down terraces and permitted aggradations of overlying fluvio-tidal point bars to accumulate into giant commercially attractive sand complexes. The internal architecture of these tens of metres thick sand deposits included deposit-wide erosion surfaces resulting from cycles of collapse–subsidence, stabilized substrate and erosion, and renewed subsidence and aggradation.

scholarly journals SAND TRANSPORT DURING CLOSURE OP TIDAL CHANNELS

1972 ◽  
Vol 1 (13) ◽  
pp. 43
Author(s):  
J.N. Svasek ◽  
J.H.J. Terwindt ◽  
A.W. Walther
Keyword(s):  
Building Material ◽  
Stationary Flow ◽  
Sand Transport ◽  
Suspended Material ◽  
Tidal Channels ◽  
Dumping Site ◽  
Closure Operations

A method is presented for estimating the dredger capacity required for closing tidal gaps with sand as the only building material. The method is based essentially on a relation between parameters describing the flow of the water and the resulting sand transport. Empirically determined coefficients are used to approximate the effects of the non-stationary flow in the gap and the supply of suspended material at the dumping site. The experiences gained at a number of closure operations are discussed and compared with the computations.

COASTAL ALTERATION AND CHANGES IN SHORELINE MORPHOLOGY DUE TO ARTIFICIAL STRUCTURES IN MIIRAKU TOWN ON FUKUE IS. IN THE GOTO ARCHIPELAGO

2017 ◽  
Author(s):  
Ryo Sakamoto ◽  
Ryo Sakamoto ◽  
Satoquo Seino ◽  
Satoquo Seino ◽  
Hirokazu Suzaki ◽  
...  
Keyword(s):  
Tang Dynasty ◽  
National Park ◽  
Survey Methods ◽  
Aerial Photographs ◽  
Sand Transport ◽  
The Status ◽  
The Tang Dynasty ◽  
Coastal Changes ◽  
Century Poetry ◽  
Nagasaki Prefecture

A construction of breakwaters and other shoreline structures on part of a coast influences drift sand transport in the bay, and causes comprehensive topographic changes on the beach. This study investigated shoreline and coastal changes, taking as an example of Shiraragahama Beach in Miiraku on the northwestern end of Fukue Island, Nagasaki Prefecture (Kyushu, Japan). Miiraku, adjacent to Saikai National Park, appears in the revered 8th century poetry collection “Manyoshu” and served as a port for a ship taken by the Japanese envoy to China during the Tang Dynasty (618-709). Because of the recent development of breakwaters for a fishing harbor, the shore environments of this beach have changed significantly. In this study, the status of silt deposits and topographic changes on this beach arising from the construction of a harbor breakwater were evaluated by comparing aerial photographs taken in different years. Next, the changes in the shoreline visible from aerial photographs from 1947 to 2014 were analyzed. Lastly, the altitude of the beaches was measured using accurate survey methods. The following results were obtained: 1) coastal erosion made rock cliffs to fall off along the shore and deposited sand on this beach; 2) the more serious advances or retreats of the shoreline took place around shoreline structures; 3) sandbars and beach cliffs were formed.

PREDICTION OF TOPOGRAPHIC CHANGES ON FORESHORE AND BACKSHORE WHEN LONGSHORE SAND TRANSPORT WAS BLOCKED BY FLOODWAY

2018 ◽  
Vol 74 (2) ◽  
pp. I_871-I_876
Author(s):  
Toshinori ISHIKAWA ◽  
Takaaki UDA ◽  
Masumi SERIZAWA ◽  
Shiho MIYAHARA ◽  
Ryo MOROHASHI ◽  
...  
Keyword(s):  
Sand Transport
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