Optimization of Nearshore Dredge Pit Design to Reduce Impacts on Adjacent Beaches

Benedet, Lindino; Finkl, Charles W.; Dobrochinski, J.P.H.

doi:10.2112/jcoastres-d-12-00126.1

Cited by 8 publications

(5 citation statements)

References 9 publications

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“…The numerical model setup with a wave climate that showed the best fit against the benchmark is used to investigate coastal engineering interventions designed to reduce sand volume loss from the Delray Beach nourishment project. Alternatives evaluated include removing all the offshore dredge pits by sediment re-filling, re-filling the deepest dredge pits identified as the main causes for the erosional hot spot by Benedet et al (2013) at the south end of the nourishment project, adding a breakwater field consisting of three breakwaters at the south end of the nourishment project and lastly adding a groin field consisting of three groins at the nourishment's downdrift (south) end.…”

Section: Introductionmentioning

confidence: 99%

A morphological modeling study to compare different methods of wave climate schematization and evaluate strategies to reduce erosion losses from a beach nourishment project

Benedet

Dobrochinski²,

Walstra

et al. 2016

Coastal Engineering

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Section: Introductionmentioning

confidence: 99%

A morphological modeling study to compare different methods of wave climate schematization and evaluate strategies to reduce erosion losses from a beach nourishment project

Benedet

Dobrochinski²,

Walstra

et al. 2016

Coastal Engineering

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“…A variety ofstudies (Benedet and List, 2008;Benedet et al, 2013;Lopes et al, 2009;Work et al,2004 and many others) have examined the impacts of dredging on nearshore wave processes and the subsequent shoreline response for sandy beaches.While sandy beaches maymorphodynamically adjust to the dredgingover time,the excavation pit on the reef flat is, however, a more permanent and static feature. Few studies have examined the impacts of such anthropogenic modifications to the reef flat on the nearshore hydrodynamics.…”

Section: Introductionmentioning

confidence: 99%

Modeling wave processes over fringing reefs with an excavation pit

Yao

Becker

Ford

et al. 2016

Coastal Engineering

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The excavation of reef-flat sand and aggregate for engineering projects is a common practice on atoll islands, with attendant coastal management and hazard mitigation issues. To assess the impact of reef-flat excavation pits on wave transformation, a numerical study is carried out based on one-dimensional weakly dispersive, highly nonlinear Boussinesq equations. Model simulations are compared to field observations made at Majuro Atoll, Republic of the Marshall Islands (Ford et al., 2013a) at a 75-m wide fringing reef flat with a 17-m wide, 4-m deep excavation pit and at an adjacent unmodified reef flat. With a calibrated empirical breaking model and uniform friction coefficient, the numerical model is shown to satisfactorily reproduce the observed sea and swell (SS) and infragravity (IG) frequency band wave heights for a moderate amplitude wave event. By removing the lateral morphological differences of the field experiment, the model shows that an excavation pit reduces/increases shoreline IG /SS wave heights compared to numerical tests without the pit, in qualitativeagreement with Ford et al. (2013a). An EOF analysis demonstrates that the reduction in IG wave heights is associated with modifications of the ¼ and ¾ wavelength IG standing modes across the reef caused by the pit. Model tests are used to evaluate the effects of cross-reef pit location and width on wave transformation. Shoreline wave heights are least affected by a pit located near the reef crest, and both SS and IG wave heights increase as the pit location moves shoreward.Shoreline wave heights are an increasing function of pit width as the increase in SS wave height exceeds the decrease in IG wave height produced by the 3 pit. The effects of incident wave height and spectral bandwidth are also examined for the reef with and without pit. It is found that both shoreline SS and IG wave heights increase with the increasing incident wave height for both profiles. The numerical model results also demonstrate that the shoreline response is sensitive to the bandwidth of the incident wave spectrum, and larger IG shoreline wave heights are excited for narrower spectral bandwidths until wave reflection limits the forcing.

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“…A failed riverbank would indicate channel migration and loss of precious land surface (Arora, Patel, Lade, & Kumar, 2023; Yu et al, 2015). The river migration affects various water exchange infrastructural projects installed close to the riverbanks, such as water supply for a nearby community or dumping treated wastewater (Benedet et al, 2013). Anthropogenic activities like near shore constructions, river encroachments, bridge construction, port construction, and sediment mining have been done for decades.…”

Section: Introductionmentioning

confidence: 99%

“…close to the riverbanks, such as water supply for a nearby community or dumping treated wastewater (Benedet et al, 2013). Anthropogenic activities like near shore constructions, river encroachments, bridge construction, port construction, and sediment mining have been done for decades.…”

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confidence: 99%

The riverbank vegetation for mitigating the adverse effects of sediment dredging

Arora,

Kumar

2024

Ecohydrology

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Sediment dredging has been an ever‐growing issue, especially in developing nations with high demand for concrete filler material. River systems are adversely affected by sediment mining, resulting in decreased stability of the riverbed and riverbanks. Nature‐based solutions for riverbank erosion have been a research topic that has led to the proposal of vegetation on the riverbanks. However, little is known about the extent of riverbank vegetation required to negate the devastating effects of sediment mining because dense vegetation severely affects the flow structure and becomes a waste trap. This experimental study uses sparsely dense, flexible, and bladed vegetation to study the annulment effects of vegetation against the existing mining pit. Near‐bed turbulence and sediment transport have increased in the test section in the presence of a mining pit. The increase in near‐bed streamwise and transverse Reynolds shear stresses helped us understand the increased sediment movement in streamwise and lateral directions. The morphology of the test section showed increased riverbed erosion at the beginning of the test segment. The entire cross‐section was levelled at the end of the test section, and aggradation was downstream of the test segment. In contrast, in the vegetated riverbank case, the initial profile of the bank was almost unchanged for the same discharge of flow and upstream sand pit. The sparse vegetation overperformed the intended negation effects. This study establishes that sparse vegetation would perform better in maintaining the channel morphology, which otherwise in dense vegetation would have faced a high erosion rate in the main channel while giving the same protection to the riverbanks.

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Optimization of Nearshore Dredge Pit Design to Reduce Impacts on Adjacent Beaches

Cited by 8 publications

References 9 publications

A morphological modeling study to compare different methods of wave climate schematization and evaluate strategies to reduce erosion losses from a beach nourishment project

A morphological modeling study to compare different methods of wave climate schematization and evaluate strategies to reduce erosion losses from a beach nourishment project

Modeling wave processes over fringing reefs with an excavation pit

The riverbank vegetation for mitigating the adverse effects of sediment dredging

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