Gabion as a coastal protection structure: a case study in Panjang Island Indonesia

Panjang Island is a small island in Jepara, Indonesia which is very vulnerable to coastal damage due to crashing waves. Therefore, presence of coastal protection structure is essentially important. Gabion structure was constructed to protect this coastal area. Considering the age, the existing gabion structure needed assessment and analysis to ensure its performance in term of protecting the coastal area. This study aimed at assessing and analyzing the performance of the existing gabion structure. Data of the study were collected through observing the condition of the structure. Assessment was carried out by scaling 1 (minor) to 5 (severe damage). Results of the analysis showed that the value of stability to overturning was 3.96, while the stability to shearing was 2.07, the structure stability was in safe category. Soil pressure under the structure in σ max. was 0.39 kg/cm2, while σ min was 0.16 kg/cm2, which means safe. The condition of gabion as a coastal protection structure in section 1 was partially damaged with a moderate level of damage, in section 2, the damage was revealed to be a minor level of damage, while in section 3, the damage was in a minor level of damage.

Estimating zonal Ekman transport along coastal Senegal during passage of Hurricane Fred, 30–31 August 2015

We examine the role of zonal Ekman transport along the coast of Senegal on 30 August 2015 when the tropical disturbance associated with Tropical Cyclone Fred was located to the west of Senegal, causing considerable coastal damage in the southern Senegal–Gambia domain (south of Dakar, Senegal). Ten-meter winds from three Weather Research and Forecast model simulations were used to estimate zonal Ekman transport, when the maximum values were found on 30 August. These simulations are in agreement with limited coastal observations showing increasing southerly wind speeds during 30 August but overestimated relative to the three coastal stations. The strong meridional winds translate into increased zonal Ekman transport to the coast of Senegal on 30 August and are likely responsible for some coastal flooding. Ekman transport along the coast contributes significantly to the water-level variations during swell events. The use of a coupled ocean model will improve the estimates of Ekman transport along the Guinea-Senegalese coast. The observed damage suggests that artificial and natural barriers (mangroves) should be strengthened to protect coastal communities in Senegal.

Peningkatan kapasitas kesadaran masyarakat terhadap mitigasi kerusakan pantai di Kelurahan Pelintung, Kecamatan Medang Kampai Kota Dumai-Riau

Along the coast Keluruhan Pelintung has been an abrasion of 1.33-16.84 metres/year. This activity aims to increase the capacity of community awareness of coastal damage mitigation through counseling on abrasion prevention and green belt implementation techniques. The methods used were lectures, discussions, and classroom and field practice, followed by 28 community representatives. The results of the activity showed a significant increase in community's understanding of simple methods to prevent coastal damage which had a positive impact on ecology (coastal resilience) and the economy (alternative income). The method of planting mangroves on abrasive beaches is due to the influence of currents and waves and processing of mangrove fruit to produce syrup, diamonds and mangrove dodol (mangrove). The results of the economic analysis show that the pedada syrup (1 bottle @ Rp. 25,000) generates a profit of Rp. 3,192,000/month, wajik pedada (1 pack Rp. 10,000) Rp. 1,476,000/month, and dodol pedada (1 pack of Rp. 15,000) Rp. 2,760,000/month. The majority of the community stated that they supported and enthusiastically held this activity, namely 49.7% (Strongly Agree), 37.8% (Agree), 11.80% (Neutral) could accept and practice increasing community awareness of mitigating coastal damage by making mangrove planting efforts and diversification of processed mangrove products.

ANALYSIS OF SHORELINE CHANGE IN COASTAL AREA OF SUBANG WEST JAVA INDONESIA FROM 2010 TO 2019 THROUGH SATELLITE IMAGERY

The condition of beaches in Indonesia is currently quite concerning. Indonesia's mangroves and coastal sand are in danger of being damaged. Commitment from all parties is needed to overcome coastal damage. If not, the negative impact will be dangerous for the existence of coastal communities. Damage to coastal is a serious threat to the surrounding ecosystem, even tends to harm humans. Not only waste carried by the flow into the sea, but also garbage disposed of around the coastal areas of the sea and poor land management are clearly some actions that can reduce the carrying capacity of the environment. This carriage a serious threat to the environment. The beach in Subang district, West Java has quite severe coastal damage. Analysis of shoreline changes is needed to overcome the damage to the coast. The method used to analyze shoreline changes is through satellite mapping using Google Earth. The results obtained from 10 years of coastline satellite mapping in Subang Regency are changes in coastline and area that occur due to erosion and/or accretion. These results will help to challenge erosion and/or accretion. The next step can be made a coastal protection in the form of mangrove plants or coastal protection structures.

Nearshore Dynamics of Storm Surges and Waves Induced by the 2018 Typhoons Jebi and Trami Based on the Analysis of Video Footage Recorded on the Coasts of Wakayama, Japan

In this study, field surveys along the coasts of Wakayama Prefecture, Japan, were first conducted to investigate the coastal damage due to storm surges and storm-induced waves caused by the 2018 Typhoons Jebi and Trami. Special focus was placed on the characteristic behavior of nearshore waves through investigation of observed data, numerical simulations, and image analysis of video footage recorded on the coasts. The survey results indicated that inundation, wave overtopping, and drift debris caused by violent storm-induced waves were the dominant factors causing coastal damage. Results of numerical simulations showed that heights of storm-induced waves were predominantly greater than storm surge heights along the entire coast of Wakayama in both typhoons. However, computed gradual alongshore variations in wave and surge heights did not explain locally-concentrated inundation and run-up heights observed along the coasts. These results indicate that complex nearshore hydrodynamics induced by local nearshore bathymetry might have played a significant role in inducing such local wave characteristics and the associated coastal damage. Analysis of video footage recorded during Typhoon Jebi, for example, clearly showed evidence of amplified infragravity wave components, which could enhance inundation and wave run-up.

Estimating Zonal Ekman Transport along Coastal Senegal during Passage of Hurricane Fred (2015) from August 30 to 31, 2015

We examine the role of zonal Ekman transport along the coast of Senegal on 30 August, 2015 when the tropical disturbance associated with Tropical Cyclone Fred was located to the west of Senegal causing considerable coastal damage to coastal areas south of Dakar, Senegal. Ten-meter winds from three Weather Research and Forecast model simulations were used to estimate zonal Ekman transport, with the largest values found during the 30 August. The simulations are in agreement with limited coastal observations showing increasing southerly wind speeds during 30 August but are overestimated relative to the 3 coastal stations. The strong meridional winds translate into increased zonal Ekman transport to the coast of Senegal on 30 August. The use of a coupled ocean model will improve the estimates of Ekman transport along the Guinea-Senegalese coast. The observed damage suggests that artificial and natural barriers (mangroves) should be strengthened to protect coastal communities in Senegal.

Local government and coastal damage: confusion, potential and dreams

Purpose This paper aims to not only disentangle the recently altered law and policy on coastal management in New South Wales (NSW), Australia, but also raise opportunities for fresh ideas to develop when dealing with both existing and future coastal damage. The focus is on the role of local government which is not only closer to concerned citizens but also faces costal damage on its own doorstep. Design/methodology/approach The paper explores the topic from the beginnings of relevant statutory law to the current situation, supported by a case study. It is transdisciplinary in nature, encompassing land use and coastal legislation. Findings The narrative encourages further attention to the key issues at the local level. This is underpinned by the need for planners to move beyond zoning and other restrictive mechanisms to more strategic approaches. All levels of government must recognise that regulatory planning on its own is insufficient. This leads to the need for champions to consider opportunities beyond the ordinary. Originality/value While this paper will add to a growing literature on coastal damage and action at the local level, its emphasis on the benefits and limitations of the changing statutory system will assist not only policy makers but professional officers at the local forefront.

A Physically Based Climatology of the Occurrence and Intensification of Australian East Coast Lows

The subtropical part of the eastern Australian seaboard experiences intense cyclonic activity. The severe damage caused by the intense storms in the region, known as east coast lows (ECLs), has motivated a number of recent studies. Cyclones in this region appear to be driven by a combination of different (barotropic and baroclinic) formation mechanisms, consistent with the view emerging in the last decades that cyclones span a continuous spectrum of dynamical structures, with the barotropically driven tropical cyclone and the baroclinically driven extratropical cyclone being only the extremes of such a spectrum. In this work we revisit the climatology of cyclone occurrence in the subtropical east coast of Australia as seen in a global reanalysis, systematically applying classification criteria based on the cyclone vertical structure and thermal core. Moreover, we investigate the underlying processes driving the cyclone rapid intensification by means of an atmospheric limited-area energetics analysis. We show that ECLs have different spatial patterns according to the cyclone thermal structure, with the fraction of hybrid cyclones being larger toward the tropics and closer to the coast. Moreover, we find that explosively deepening cyclones in this region are driven by a different combination of processes with respect to the global case, with barotropic processes in the surrounding environment having a more dominant role in the energetics of cyclone rapid intensification. The findings of this work contribute to understanding the physical processes underlying the formation and intensification of Australian east coast lows and the associated coastal damage and risk.

ANALISIS KERENTANAN PANTAI MENGGUNAKAN COASTAL VULNERABILITY INDEX (CVI) DI WILAYAH PESISIR TANJUNG PANDAN, KABUPATEN BELITUNG

Wilayah pesisir Tanjung Pandan terdiri atas Kelurahan Air Saga, Tanjung Pendam dan Kampung Parit dan merupakan pusat ibukota Pulau Belitung. Tingginya kegiatan perikanan dan aktivitas manusia di wilayah ini menyebabkan perlunya kajian mengenai analisis kerentanan pantai guna melakukan upaya pencegahan kerusakan pantai dan pengelolaan wilayah pantai secara berkelanjutan. Tujuan dari penelitian ini adalah untuk mengetahui tingkat kerentanan dan lokasi kerentanan pantai yang paling tinggi serta variabel yang paling berpengaruh terhadap kerentanan pantai. Penelitian ini dilaksanakan pada bulan Mei 2018 dengan menganalisis variabel geomorfologi, erosi/akresi, kemiringan pantai, jarak tumbuhan dari pantai, pasang surut dan tinggi gelombang sesuai dengan indeks kerentanan pantai. Metode pengambilan data lapangan dilakukan melalui pengamatan secara langsung dengan pembagian sel pantai sebanyak 7 sel serta berdasarkan data sekunder. Hasil penelitian menunjukkan bahwa nilai CVI sel pantai 1-5 dan 7 tergolong kategori kerentanan rendah dengan nilai CVI berkisar antara 14,43 – 20,41, sedangkan sel pantai 6 tergolong kategori kerentanan menengah dengan nilai CVI 22,82. Lokasi kerentanan paling tinggi berada pada sel pantai 6 dengan kondisi geomorfologi pantai pasir serta paling dipengaruhi oleh variabel perubahan garis pantai akibat terjadinya peristiwa erosi. Tanjung Pandan Coastal Area consists of Air Saga, Pendam Cape and Kampung Parit region that are the centre of Belitung Island. The high activity of human and fisheries in the area cause the coastal vulnerability that need to be examined to prevent coastal damage and to manage the coastal area in a sustainable way. This study was conducted in May 2018 by analyzing geomorphology, shoreline erosion/accretion, coastal slope, plants distance from the coast, mean tide range and mean wave height based on coastal vulnerability index within direct observation at seven coastal cells and based on secondary data. The research showed that the CVI value on the 1st – 5th cells and the 7th cell categorized at low level with a range between 14,43 – 20,41, while the 6th cell categorized at medium level with the CVI value 22,82. The highest vulnerability located on the 6th cell with a sandy beach geomorphology and most affected by coastline changes variable due to the occurrence of erosion.