Seawall Research Articles

Experimental Study of Overtopping on Sea Dikes and Coastal Flooding Under the Coupled Processes of Tides and Waves

Experimental Study of Overtopping on Sea Dikes and Coastal Flooding Under the Coupled Processes of Tides and Waves

Land Procurement for Public Interest Against Destroyed Land: Natural Events and Legal Certaint

Based on a case study on the construction of the Semarang-Demak Toll Road, this study aims to investigate and investigate land acquisition for the public interest for land that has been destroyed as a result of natural events and its legal certainty. The research method used is socio-legal with primary data in identification, field measurements, and other supporting data. Semarang-Demak Toll Road property acquisition demonstrated tidal inundation on the north shore. Subsidence exacerbates Semarang's flooding. On flooded land, sea dikes and retention ponds prevent tidal floods. If just for transportation, the Semarang-Demak Toll Road can be built in flood-free areas or over the sea, like Bali's Mandra Toll Road. Land acquisition concerns delayed the Semarang-Demak Toll Road. Lack of land limitations has delayed land purchases. In the Semarang-Demak Toll Road land acquisition, destroyed land is not a problem under Indonesian law. 2021's Regulation 18 defines destroyed land. Destroyed land will drive people to take better care of their land and be more concerned about global warming or land subsidence. The state honors the landowner's emotional connection by paying for spiritual care. Doi: 10.28991/CEJ-2022-08-06-06 Full Text: PDF

An Integrated GIS Method – The Influence of Human Activities on Shoreline Change in Western Indian Small Island States: A Two Centuries Analysis of Urban West Unguja - Zanzibar Shoreline

Purpose: Urban areas have a high impact on shoreline changes that are more influenced by human activities rather than natural factors, together with hard structural mitigation and management, which are more practiced compared to other areas. This paper describes shoreline changes of small islands specifically; the shoreline of Urban West of Unguja Island in Zanzibar United Republic of Tanzania. This island has been changed for 174 years in different stages due to human activities including; reclamation of Darajani creek, port expansion at Malindi, Mtoni beach nourishment, sewer and stormwater channeling at Kilimani, construction of walls, groins, jetties, etc. 
 Methodology: The study uses an integrated method to analyze and detect changes using a sketch plan survey map of 1846 and 1892, a topographic map of 1907 and 1987, an aerial photo of 2004, Landsat images, and google images of 2019 and 2020. These maps were carefully georeferenced with latitude and longitudes, digitized using ArcGIS and demarcated along the study area supported with ground truth observation to analyze the coastal shoreline changes.
 Findings: The results show that the area experiences more accretion rather than retreat, integrated analysis and projections of the overall accretion and retreat for 174 years is 1,527,693.85 m2 (1.53 km2) and -936,135.48 m2 ( -0.94 km) receptively. The average accretion of land from 1846 to 2020 is 8,779.85m2/yr. (0.0088 km2/yr.) and retreat is -5,380.09m2/yr. (-0.0054 km2/yr.). A major accretion was observed and detected during the early 1900s to late 1987 which were major land transformation while other minor development activities were between 2010 to 2020. Sea walls, groins, beach nourishment, mangroves, barrier islands, and islets are major management practices of the shoreline which show a positive impact.
 Recommendations: The study finds it more appropriate to use multi datasets as an integrated method to analyze long-term coastal shoreline changes especially when there is limited data.

A New Approach of the Tsunami Mitigation Strategies for the City of Banda Aceh, Indonesia

Ten years after rehabilitating and reconstructing some coastal areas of Banda Ache struck by the tsunami, and the city is currently repopulated, with most of its open land and community ponds converted into settlements. This rise in population needs to be controlled to minimize damages and casualties, assuming the tsunami hits again. Presently, the Banda Aceh City spatial plan for 2029 does not have a clear concept of tsunami mitigation, specifically in the spatial pattern of coastal areas. Therefore, this research aims to remap the vulnerability level of the Banda Aceh City coastal area from the tsunami hazard and determine alternative strategies based on the tsunami level in achieving safe, comfortable, productive, and sustainable spatial planning goals. This starts by analyzing the wave height generated by the earthquake that triggered this natural disaster and mapping the spatial distribution of the area and the tsunami's inundation height. The results showed that the proportionate regions prone to Level-2 tsunami were worse than the 2004 disaster based on the water level markers built in the city. The spatial planning strategies for the coastal area of Banda Aceh City are carried out by determining the level of tsunami-prone and the potential of the area's resources through a new approach of the multi-layer tsunami defence systems by combining sea dike, greenbelt, silvo-fishery, and the elevated road.

Development of post-disaster shelters (case study: Gampong Pande post-rehabilitation and reconstruction of the earthquake and tsunami disaster)

Indonesia has a high risk of earthquake and tsunami disasters, especially in areas around the long and relatively sloping coastline. Nanggroe Aceh Darussalam as an area that has been hit by an earthquake and tsunami, in its development of settlements it is more directed to disaster-prone areas in coastal areas. This study aims to identify the development of housing after rehabilitation and reconstruction due to the earthquake and tsunami in the Gampong Pande area, in the context of mitigating earthquake and tsunami disasters in the future. This research is related to ethnographic research that uses an emic approach in field surveys, emphasizes the natural setting context, focuses on interpretation and meaning, involves the community deeply, and focuses on contemporary phenomena as a whole. Post-disaster mitigation actions carried out in residential development are structural modifications referring to and in line with the Building Code. Post-disaster mitigation actions carried out in the development of residential areas are land grants for road widening as an evacuation route during disasters and the construction of sea dikes to reduce tidal waves of sea water entering settlements and planting mangroves along the sea wall as a green belt that doubles as a green belt and source of fishermen’s economy.

APPLICATIONS OF DUYEN HAI - 1 THERMAL POWER PANT’S FLY ASH AND HOA PHAT STEELMAKING PLANT’S BLAST FURNACE SLAG IN GEOPOLYMER CONCRETE FABRICATION

Currently, non-cement alkaline activated concretes, using fly ash instead of conventional cement binder, have been widely used in construction around the world. However, in Viet Nam researches on geopolymer concretes are still very limited. Meanwhile, coal-fired thermal power plants in Viet Nam annually generate about 13 million tons of fly ash, potentially causing environmental pollution. Therefore, the use of these raw materials for concrete making not only minimizes environmental pollution but also avoids wasting resources. This paper presents study results on the mechanical properties of geopolymer concrete using fly ash of the 1,245 MW Duyen hai - 1 thermal power plant and blast furnace slag of Hoa Phat steelmaking plant. The suitable ratio of liquid glass/NaOH used in this study was about 3.7. At this value, the compressive, flexural and tensile strengths of the geopolymer concrete have reached 43.2 MPa, 6.62 MPa and 87,780 N, respectively. In addition, geopolymer concrete samples were impervious and their mechanical properties were almost unchanged after soaking in various solutions for a period of 4 months. Furthermore, interlocking blocks were fabricated from this geopolymer concrete (with the same composition as sample M6), based on the TCVN 9901:2014 standard on Hydraulic structures and Requirements for sea dike design. These blocks were used to reinforce the sea dike against this year’s typhoon season in central Viet Nam. The success of this project greatly contributes to the effective application of fly ash and reducing environmental pollution.

Analysing the trend of beach–dune erosion in Digha coastal tract in response to nearshore wave processes and coastal protection structures

Digha is one of the largest sea resorts in eastern India, facing a long history of erosion and has been engineered extensively since 1970s. It extends for 5.45 km along the Medinipur coast, which can be divided into three sectors viz. New Digha, Old Digha and Gangadharpur based on the beach character. The current study aims to identify the erosion–accretion trend of the coast and link it with the phases of construction of the coastal engineering structures in this zone, understanding the nearshore wave climate, and finally quantify the influence of these structures on the spatio-temporal variability of beach dynamics. Keeping these objectives in mind, DSAS was used to generate data on erosion–accretion regimes of the study area. A number of beach-profiles have been systematically surveyed during 2011–2019. The results show that between 1973 and 1998, the coastline at Old and New Digha retreated by about 200 m and 180 m, respectively, and were later constrained by the sea wall, while Gangadharpur suffered severe erosion (about 350 m) due to the impact of the refracted waves at the abrupt termination of the sea wall after Old Digha. Due to the low chance of energy dissipation , the beach at Old and New Digha has lowered drastically (average 3.50 m and 1.5 m respectively) and has largely moved away from the equilibrium condition. At Gangadharpur, the effect of the groyne in raising the beach elevation is jeopardised by a newly constructed wall in this sector, which has interrupted the process of beach–dune sediment exchange in this area.

Climate Change Impacts of Sea Level Rise on the Saemangeum Sea Dike

The Saemangeum Sea Dike, completed in 2011 in South Korea, is the longest sea dike in the world. One of the most pressing issues of today, climate change leads to sea-level rise that could increase the risk of sea dike overflow. However, what impact climate change will have on the Saemangeum Sea Dike has not been verified yet. Here, we estimate the impacts of sea-level rise on the Saemangeum Sea Dike, using the Linear Regression Analysis method, the Continuous Wavelet Transform (CWT) method, and the Ensemble Empirical Mode Decomposition (EEMD) method. The sea level data of the Saemangeum area over the last 30 years were analyzed, and the results showed that the maximum rate of sea-level rise of the Saemangeum Sea Dike is at 2.51 mm/year when the EEMD method was applied. It means that the impact of sea-level rise on the Saemangeum sea dike is reasonably low because the sea level rise will exceed the freeboard after 366 years, so there is currently no clear sign that it poses a problem.

Numerical Study on Wave Run-up to Identify the Most Effective Design of Jakarta’s Outer Sea Dike

The National Capital Integrated Coastal Development (NCICD) is a construction megaproject around Jakarta Bay targeted environmental revitalization and flood mitigation. One of the main projects of NCICD is to develop the Jakarta’s outer sea dike to prevent future disasters triggered by the increase of the sea level around Jakarta Bay. In this paper, we aim to assess and optimize the design of Jakarta’s outer sea dike by investigating the wave run-up phenomenon, which is measured as the maximum vertical extent of wave uprush on a structure above the still water level. We used the Non-linear Shallow Water Equations (NSWE) as our mathematical model to simulate this phenomenon. The NSWE model was solved numerically using the finite volume method on a staggered grid with a wet-dry procedure to obtain accurate wave run-up height. To validate our numerical scheme, we conducted benchmark tests against a publicized experimental dataset, resulting in a good agreement between the numerical and experimental data, which confirms the robustness and accuracy of our model. We then simulate the wave run-up over three different sea dike profiles: single slope, single berm, and single berm with rocks. Our study shows that among the cases we investigated, the single berm with rocks is the most effective design of the sea dike as even small-sized rock units can significantly reduce the wave run-up height.

Analisis Hidrologi untuk Perencanaan Sistem Polder di DKI Jakarta

The application of the polder system for flood control in DKI Jakarta has become a must for coastal areas, especially with the construction of sea dikes along the coast of Jakarta as a solution to anticipate tidal flooding. One thing to consider when using a polder system in flood control is how much pump capacity and reservoir are needed. To answer this quetions, a hydrological analysis has been carried out with several method approaches, starting from determining the rainfall design in the form of a depth duration frequency curve in 1 hour to 48 hours, and then applied area reduction factor (ARF) to corrected rainfall design. Natural Resources Conservation Service (NRCS) method are uses to calculated runoff or effective rainfall and then with the unit hydrograph by time area method to produce a runoff hydrograph. Based on this approach, the Sentiong Polder plan has been carried out with the result that the required pump capacity for a 25-year return period is 32 m3/s and 50 m3/s for a 100-year return period with a storage capacity used of 1,507,500 m3. If you want to reduce the pump capacity, it is necessary to increase the storage capacity.

Sustainable land reclamation in coastal area

Many land reclamation projects have been carried out worldwide for many years to create new land from oceans, seas, riverbeds or lakebeds for several purposes. Historically, agriculture was the first drive for land reclamation, followed by urbanization and industrialization. Recent worldwide globalization has enhanced international trading and promoted many land reclamation projects in coastal areas. Land reclamation requires a large amount of relatively high-quality fill soil, which is used to obtain from mountains, rivers and seabeds. For this purpose, many land reclamation projects have been carried out together with other projects, such as dredging projects at rivers and coastal areas and/or the development of mountainous areas. Recently, it has become difficult to obtain such soil at reasonable cost because of restricted environmental protection, which requires the use of lower-quality soil as a reclamation material. Reclaimed land and sea walls are highly susceptible to ground instability, ground settlement and soil liquefaction, which can amplify the amount of damage to buildings and infrastructure there. Various ground improvement techniques have been developed to assure the stability of the sea wall and reduce and accelerate the ground settlement of reclaimed land. As environmental issues have become very critical in recent years, it is necessary to develop sustainable land reclamation techniques to promote the beneficial use of dredged soil and waste, minimize the environmental impact and create a rich natural environment. In this manuscript, the history of land reclamation in the Tokyo Bay area is briefly introduced, and current technologies regarding ground improvement and preservation of environmental conditions are presented to determine the future trends of sustainable land reclamation technologies.

Distribution Strategies of Vascular Plants at the Reclaimed Lands at the Saemangum Sea Dike

The distribution of plant communities in the reclaimed land of the southwestern coasts of South Korea, along with the environmental or plant factors, was studied through canonical correspondence analysis (CCA) and the competitor (C), stress tolerator (S), and ruderal (R) (CSR) ecological strategies. The coastal reclaimed land plants were classified into three plant-factor groups in the CCA biplot diagram. Axis1 was correlated with LS, SLA, CH, and FS. Axis 2 was correlated with LDMC, FP, and LDW. The reclaimed landplants were classified into three soil-factor groups in the CCA biplot diagram. First, the group factor was correlated with SAND. Second, the group factor was distributed according to T-N and TOC. Third, the group factor was distributed according to Salinity content. To clarify the relative significance of competition, stress, and disturbance in the distribution process of plant communities, the CSR distribution model was adopted. Sixteen of the 19 species were allocated to the factors related to the ruderals strategies such as R/CR and CR including R/CSR, SR/CSR, and CR/CSR, and SC strategies. They displayed ruderal and competition adaptation strategies reflecting the ecological environment. Seven species showed R/CR (ruderal/competitor-ruderal) strategies; Aeschno meneindica, Chenopodium album var. centrorubrum, Lolium perenne, Lotus corniculatus var. japonicus, Phragmites communis, Portulaca oleracea, and Soncous brachyotus and 6 species showed CR (competitor-ruderal) strategies; Bidens frondosa, Echinochloa crus-galli, Echino chloaoryzicola, Erigeron canadensis, Fimbristy lislongispica and Setaria viridis. The three species with R-related strategies were Artemisia princeps, Lolium perenne, and Trifolium repens. The distribution patterns of the CCA diagrams and CSR triangles may provide a useful scientific basis for protecting and restoring reclaimed lands and their valuable ecosystem services, from the increasing disturbances.

Wave trapping by a submerged permeable flexible membrane near an impermeable sea wall

Wave trapping by a submerged permeable flexible membrane near an impermeable sea wall

Mere Nuisance or Growing Threat? The Physical and Economic Impact of High Tide Flooding on US Road Networks

High tide flooding (HTF) already affects traffic in many US coastal areas, but the issue will worsen significantly in the future. While studies show that large storm surge events threaten to be ever more costly, less damaging, but more frequent HTF events remain understudied and potentially carry a comparable economic impact. This study advances our understanding of the risks and impacts of HTF on vulnerable traffic corridors using hourly tide gauge water levels, sea-level rise projections, and link-level spatial analysis. It is the first study to estimate HTF economic impacts for varying levels of intervention, including reasonably anticipated driver-initiated rerouting and ancillary protection of adjacent property. The 2020 annual national-level costs of $1.3 to $1.5 billion will increase to $28 to $37 billion in 2050 and $220 to $260 billion in 2100 for medium to high greenhouse gas (GHG) emissions scenarios, respectively. Total costs over the century are $1.0 to $1.3 trillion (discounted 3%). Additional cost-effective protection by building sea walls or raising road surfaces could significantly reduce 2100 costs to $61 to $78 billion, but there remain many barriers to adopting least-cost adaptation decisions, and these gains may only be realized with careful planning and information sharing.

Wave Interactions with Coastal Structures

Due to the ongoing rise in sea level and increase in extreme wave climates, consequences of the changing wave climate, coastal structures such as sea dikes and seawalls will be exposed to severe and frequent sea storms [...]

Planning for Earthquakes and Tsunamis: Lessons from Japan for British Columbia, Canada

In this paper I consider how international experience in the management of catastrophic natural disasters might be transferable across jurisdictions by comparing two study areas, the Tōhoku coastal region of northeast Japan, and the coastal area of southwest British Columbia (BC), Canada. I present a conceptual framework recognizing that good practice from one jurisdiction can be useful in improving disaster management planning in another. This framework also underscores that disaster management experience from overseas should be interpreted carefully, taking into account national and local conditions. Empirically, I re-examine the 2011 Great Japan Earthquake and the stricken Tōhoku region at the time of its tenth anniversary to see what lessons might be learned for disaster planning in southwest BC. Both study areas face exposure to hazards involving low probability/high impact mega-earthquakes and tsunami, and both have taken steps to reduce the vulnerability of coastal communities and infrastructure. In the case of the BC southwest coast this region is vulnerable to both a catastrophic magnitude 9 earthquake and tsunami resulting from the rupture of the Cascadia Subduction Zone (CSZ). When compared to Japan, however, BC lacks a history of major seismic events close to population centers and has little direct experience of planning for large earthquakes and tsunami events along its coastline. To help discern which particular features of Japan’s planning for (and response to) the Great East Japan Earthquake might yield policy implications for BC, I use the four pillars of disaster management as analytical tools: (1) the mitigation of risk, (2) disaster preparedness, (3) the emergency response, and (4) post-disaster recovery. The study methodology involved extensive site visits to both the Tōhoku region of Japan and southwest BC, face-to-face interviews with disaster managers and first responders, a review of relevant policy documents and reports of the Great East Japan Earthquake, together with a review of current disaster management practice in BC. The results revealed interesting comparisons between the two jurisdictions, signaling that the Japanese system had moved to a ‘culture of preparedness’, whereas the BC system was still being modernized to focus on proactive disaster planning. There are many policy suggestions from the Japanese experience in 2011 that deserve consideration for adapting into BC earthquake and tsunami planning. These include the urgency of seismic retrofitting programs, the adoption of a pro-active approaches to triggering emergency recovery operations, advance coordination with construction companies to assist relief and recovery as well as advance planning for large-scale temporary housing programs. The challenges and policy missteps experienced in Japan’s planning and response operations at the time of the Great East Japan Earthquake are also noted, such as an overreliance on sea walls to prevention tsunami inundation, together with deficient escape plans in some local communities.

Monitoring the erosion and accretion of a human-built living shoreline with drone technology

Climate change is forcing coastal communities to adapt to rising sea levels and increased storm activity. Living shorelines are a new adaptation to reduce the resulting erosion and inundation. Living shorelines use a variety of salt-tolerant plants and other natural material to absorb the increased wave energy and sea levels along the coast while supporting an enlarged coastal habitat for a variety of plants and animals, improving coastal resiliency. In 2019 the coastal city of Salem Massachusetts (USA) received a grant of $216,550 to build a living shoreline (approximately 240 by 11.75 m) in a barren cove along its coastline. Drone technology was used to monitor the erosion and accretion of the new living shoreline. A dji Phantom 4 Pro with a normal color camera was flown in 2018 (before the living shoreline was established), 2019 (just after the living shoreline was created) and in 2020 (after almost 18 months of wave and tidal activity to the living shoreline). Each drone flight created three products: an orthographic mosaic, a Digital Terrain Model (DTM) and a Digital Surface Model (DSM). A ground survey was used to georeference the 2020 image and then the 2020 image was used to georeference the 2019 and 2018 images. The 2019 DTM minus the 2018 DTM accurately estimated the amount of fill used for the living shoreline within 3% of the actual amount of fill used. The 2020 DTM minus the 2019 DTM showed that 14.7% of the surface area of the living shoreline experienced erosion (24.35 m3) and 52.0% of the surface area experienced accretion (117.74 m3). Living shorelines can be widely used to protect coastal biodiversity and to adapt to rising seas and storm activity, providing a soft barrier instead of a hard barrier like sea walls.

Explanation Of Marine Lake Formation At Misool Raja Ampat West Papua, Indonesia

Marine lake in a karst landscape is one of the macro karst forms known as doline and is only found in some locations in the world. Moreover, the theory of marine doline formation is always associated with global sea-level rise which differs from one place to another due to several factors. This research was conducted to understand the formation process of marine lakes in Misool and how the water fills the basins formed especially at Holocene time. This was achieved by obtaining information on the longest underwater terrace which is also the longest standing water position recorded on the sea wall. The marine terraces were measured by sounding profiles to the sea bordering the seven marine lakes including Lenmakana, Balbullol, Lenkafal, Keramat, Karawapop, Keramat-2, and Keramat-3 as well as Harapan Jaya Sea. A total of 24 profiles were measured and stable isotopes δ18O and δD of water samples were used to determine the origin of water in the lakes. The results showed the longest terrace was at the depth of ˗33 and ˗3 m while the references from the area closest to Misool showed the same water level positions at 10,500 BP and 6,985 BP. Furthermore, the composition of δ18O and δD from lake water indicated the water samples were a mixture of groundwater and seawater with the seawater having the more dominant concentration and this allows it to fill the lake first through a previously formed cavity system.

Ecohydraulics of Surrogate Salt Marshes for Coastal Protection: Wave–Vegetation Interaction and Related Hydrodynamics on Vegetated Foreshores at Sea Dikes

Vegetation on foreshores in close vicinity to sea dikes may prove beneficial as regulating ecosystem service in the context of coastal defense, dike safety, and flood protection by reducing loads on these defense structures. Predominantly, a decrease in wave heights and bottom shear stresses is hypothesized, which calls for an inclusion in design procedures of coastal defense structures. In contrast to heterogeneous and variable salt marsh vegetation, this study uses surrogate vegetation models for systematic hydraulic experiments in a wave flume, without modeling specific plant species a priori. Froude-scale experiments are performed in order to investigate the effect of salt marsh vegetation on the wave transformation processes on the foreshore and wave run-up at sea dikes. The effect of plant and wave properties on wave transmission, energy dissipation, and wave run-up at a 1:6 sloped smooth dike are presented and discussed, focusing on the wave–vegetation–structure interaction. Vegetated foreshores can contribute to wave attenuation, where an increasing relative vegetation height hv/h results in decreased wave run-up on the dike by up to 16.5% at hv/h = 1.0.

Coastal Inundation and Land Subsidence in North Coast of West Java: A New Hazard?

The North Coasts of West Java are increasingly affected by human activities. The area has been utilized as settlement areas, industrial estates, and associated infrastructures including roads, school, hospital, market, etc. Consequently, this massive landuse and uncontrolled natural resources extraction have contributed to environmental degradation such as coastal erosion, accretion, pollution, inundation, and land subsidence. To date, we have so far very few field measurement data of land subsidence to support its importance. However, satellite image and on-ground observations used to determine spatio-temporal changes in the shoreline and area of inundation indicated the existence of land subsidence. Groundtruth data on selected areas also indicated the indicators of land subsidence such as damages of infrastructures including houses, roads, and sea dikes. The most noticeable shoreline changes in the North Coast of West Java are situated in Muara Gembong Bekasi and Legon Kulon Subang constituting maximum rates of shoreline retreat up to 200 and 150 m/year respectively for the last two decades (from 2000 to 2020). Whilst, the total areas of inundation in Muara Gembong and Legon Kulon based on recent satellite studies are 10.2 km2 and 7.4 km2 respectively. Coastal inundation might be linked to the combination of long-term behavior of oceanographic variables such as wave and sea level, in coincidence with hydrological changes due to river works (i.e. dam constructions and channellings) and an increase of settlement areas, fish ponds, groundwater extraction, etc. A set of preliminary engineering measures, in conjunction with sediment managing schemes, is proposed for the sustainable development of the coastal zone.