scholarly journals ANALISIS REFLEKSI DAN TRANSMISI GELOMBANG PADA PEMECAH GELOMBANG TIANG PANCANG

2020 ◽  
Vol 12 (3) ◽  
pp. 723-737
Author(s):  
Hendra Achiari ◽  
Ayu Libiaty Ahmad ◽  
Dede M Sulaiman
Keyword(s):  
Water Level ◽  
Sea Level ◽  
High Water ◽  
Mean Sea Level ◽  
High Water Level

Pantai berlumpur rentan terhadap kerusakan akibat gelombang, sehingga diperlukan perlindungan pantai yang salah satunya menggunakan pemecah gelombang tipe permeable. Tipe permeable yang dikembangkan ini disebut sebagai Pemecah Gelombang Tiang Pancang. Bahan yang digunakan untuk memodelkan struktur tersebut (prototipe) di laboratorium adalah bambu bulat bersekat yaitu bambu bulat dari taman Pringgodani dengan diameter 1 cm, tinggi 20 cm dengan sekat kayu multiblok setebal 2 cm. Analisis refleksi dan transmisi terhadap hasil pengujian model fisik 2D terhadap pemecah gelombang diperlukan untuk mencapai optimasi dalam penggunaannya. Hasil pengujian laboratorium membuktikan bahwa Pemecah Gelombang ini cukup efektif pada skenario yang memiliki nilai Kt yang lebih kecil dan nilai Kr yang lebih besar. Pada percobaan ini pengujian dilakukan dengan skenario tinggi muka air pada Mean Sea Level (MSL) (44 cm) dan High Water Level (HWL) (50 cm) dengan 2 skenario spasi antar tiang yaitu 1 cm dan 2 cm pada masing-masing tinggi muka air. Kemudian hasil perhitungan Kt dan Kr dibandingkan dengan variabel non-dimensional kecuraman gelombang (Hi/gT2) dan kemiringan gelombang (Hi/L) . Hasil percobaan laboratorium menunjukkan bahwa nilai Kt lebih rendah pada saat kondisi MSL, dan nilai Kr lebih tinggi pada saat kondisi MSL hal ini menunjukkan bahwa Pemecah Gelombang Bambu Bulat Bersekat ini lebih efektif pada muka air rendah dari pada muka air tinggi.

I.—The Merjelen Lake (Aletsch Glacier)

1896 ◽  
Vol 3 (3) ◽  
pp. 97-102 ◽  
Author(s):  
C. S. Du Riche Preller
Keyword(s):  
Water Level ◽  
Sea Level ◽  
High Water ◽  
High Water Level ◽  
Western Flank ◽  
Superficial Area

The Merjelen or Maerjalen Lake, situated at an altitude of 2367 metres (7750 ft.) above sea-level at the western flank of the Great Aletsch glacier, belongs to the class of glacier lakes which are found in depressions or valleys barred by glaciers whose direction of flow is more or less at right angles to the same. Like the majority of glacier lakes, it has the shape of an irregular triangle, the length being about 1.5 kilometre (nearly a mile), its greatest width 0.5 kilometre (550 yards), and its mean depth 28 metres (92 ft.). Hence its superficial area amounts to 375,000 square metres (438,000 square yards), and its volume at high-water level to about 10 million cubic metres or tons.

scholarly journals A century of sea level data and the UK's 2013/14 storm surges: an assessment of extremes and clustering using the Newlyn tide gauge record

Ocean Science ◽  
2014 ◽  
Vol 10 (6) ◽  
pp. 1031-1045 ◽  
Author(s):  
M. P. Wadey ◽  
I. D. Haigh ◽  
J. M. Brown
Keyword(s):  
Water Level ◽  
Sea Level ◽  
Return Period ◽  
Tide Gauge ◽  
Storm Surges ◽  
High Water ◽  
Lower Probability ◽  
Tide Gauge Record ◽  
Storm Activity ◽  
High Water Level

Abstract. For the UK's longest and most complete sea level record (Newlyn), we assess extreme high waters and their temporal clustering; prompted by the 2013/2014 winter of storms and flooding. These are set into context against this almost 100-year record. We define annual periods for which storm activity and high sea levels can be compared on a year-by-year basis. Amongst the storms and high tides which affected Newlyn, the recent winter produced the largest recorded high water level (3 February 2014) and five other high water events above a 1 in 1-year return period. The large magnitude of tide and mean sea level, and the close inter-event spacings (of large return period high waters), suggests that the 2013/2014 extreme high water level "season" can be considered the most extreme on record. However, storm and sea level events may be classified in different ways. For example, in the context of sea level rise (which we calculate linearly as 1.81 ± 0.1 mm yr−1 from records between 1915 to 2014), a lower probability combination of surge and tide occurred on 29 January 1948, whilst the 1995/1996 storm surge season saw the most high waters of ≥ the 1 in 1-year return period. We provide a basic categorisation of the four types of extreme high water level cluster, ranging from consecutive tidal cycles to multiple years. The assessment is extended to other UK sites (with shorter sea level records and different tide-surge characteristics), which suggests 2013/2014 was particularly unusual. Further work will assess clustering mechanisms and flood system "memory".

scholarly journals Inundation due to the tide in the context of sea level rise and the role of Can-Gio forest in the reduction of inundation

2018 ◽  
Vol 20 (K7) ◽  
pp. 76-85
Author(s):  
Hoa Thi Le ◽  
Hoa Tang My Son ◽  
Hong Thi My Tran ◽  
Giang Song Le
Keyword(s):  
Sea Level Rise ◽  
Water Level ◽  
Sea Level ◽  
High Tide ◽  
High Water ◽  
High Water Level ◽  
Maximum Water Level ◽  
Level Increase ◽  
The Future ◽  
Calculation Results

Lower basin of Sai Gon – Dong Nai river is lowland. It’s inundated at high tide. Using mathematical model method with the integrated 1D2D model, the inundation hazard due to the high tide in this region has been evaluated through the inundated area. The calculation results also showed that in the case when the damping ability of Can Gio forest is disabled high water level at Nha Be and Phu An can be increased about 2 – 3 cm and the effect will be stronger in the future following the sea level rise. In the case the Can Gio forest is diked to create a reservoir with reasonable in- and outflow directions, the high water level at Nha Be and Phu An can be decreased about 10 - 11 cm and the effect will be stronger in the future following the sea level rise. This water level decrease effect almost compensates the water level increase due to the sea level rise and keeps the maximum water level at Phu An not exceed actual one until 2050 regardless the sea level rise.

scholarly journals Determining Extreme Still Water Levels for Design and Planning Purposes Incorporating Sea Level Rise: Sydney, Australia

Atmosphere ◽  
2022 ◽  
Vol 13 (1) ◽  
pp. 95
Author(s):  
Phil J. Watson
Keyword(s):  
Sea Level Rise ◽  
Water Level ◽  
Sea Level ◽  
Tide Gauge ◽  
Water Levels ◽  
Extreme Value Analysis ◽  
Tide Gauge Record ◽  
Value Analysis ◽  
Mean Sea Level ◽  
The Impact

This paper provides an Extreme Value Analysis (EVA) of the hourly water level record at Fort Denison dating back to 1915 to understand the statistical likelihood of the combination of high predicted tides and the more dynamic influences that can drive ocean water levels higher at the coast. The analysis is based on the Peaks-Over-Threshold (POT) method using a fitted Generalised Pareto Distribution (GPD) function to estimate extreme hourly heights above mean sea level. The analysis highlights the impact of the 1974 East Coast Low event and rarity of the associated measured water level above mean sea level at Sydney, with an estimated return period exceeding 1000 years. Extreme hourly predictions are integrated with future projections of sea level rise to provide estimates of relevant still water levels at 2050, 2070 and 2100 for a range of return periods (1 to 1000 years) for use in coastal zone management, design, and sea level rise adaptation planning along the NSW coastline. The analytical procedures described provide a step-by-step guide for practitioners on how to develop similar baseline information from any long tide gauge record and the associated limitations and key sensitivities that must be understood and appreciated in applying EVA.

scholarly journals The Role of Mean Sea Level Annual Cycle on Extreme Water Levels Along European Coastline

2020 ◽  
Vol 12 (20) ◽  
pp. 3419
Author(s):  
Tomás Fernández-Montblanc ◽  
Jesús Gómez-Enri ◽  
Paolo Ciavola
Keyword(s):  
Water Level ◽  
Sea Level ◽  
North Sea ◽  
Extreme Events ◽  
Annual Cycle ◽  
Coastal Flooding ◽  
Water Levels ◽  
Total Water ◽  
Mean Sea Level ◽  
The Impact

The knowledge of extreme total water levels (ETWLs) and the derived impact, coastal flooding and erosion, is crucial to face the present and future challenges exacerbated in European densely populated coastal areas. Based on 24 years (1993–2016) of multimission radar altimetry, this paper investigates the contribution of each water level component: tide, surge and annual cycle of monthly mean sea level (MMSL) to the ETWLs. It focuses on the contribution of the annual variation of MMSL in the coastal flooding extreme events registered in a European database. In microtidal areas (Black, Baltic and Mediterranean Sea), the MMSL contribution is mostly larger than tide, and it can be at the same order of magnitude of the surge. In meso and macrotidal areas, the MMSL contribution is <20% of the total water level, but larger (>30%) in the North Sea. No correlation was observed between the average annual cycle of monthly mean sea level (AMMSL) and coastal flooding extreme events (CFEEs) along the European coastal line. Positive correlations of the component variance of MMSL with the relative frequency of CFEEs extend to the Central Mediterranean (r = 0.59), North Sea (r = 0.60) and Baltic Sea (r = 0.75). In the case of positive MMSL anomalies, the correlation expands to the Bay of Biscay and northern North Atlantic (at >90% of statistical significance). The understanding of the spatial and temporal patterns of a combination of all the components of the ETWLs shall improve the preparedness and coastal adaptation measures to reduce the impact of coastal flooding.

Numerical Simulation of Engineering Wave for Zhongzui Bay

2007 ◽  
Author(s):  
Xiejun Shu ◽  
Senhui Jiang ◽  
Ruijie Li
Keyword(s):  
Numerical Simulation ◽  
Water Level ◽  
Simulation Method ◽  
High Water ◽  
Wave Transformation ◽  
Return Periods ◽  
Engineering Construction ◽  
Wave Refraction ◽  
High Water Level ◽  
Mild Slope Equation

For providing a better shelter condition, it is necessary to build a breakwater in Zhongzui Bay. In order to know whether mooring area meets the requirement after engineering construction and compare the mooring area between solid breakwater and permeable breakwater, a numerical simulation method is used in the sheltering harbor of Zhongzui Bay. The used Mild-slope equation which describes wave refraction, diffraction and reflection, considers the steep slope bottom and effect of energy dissipation. It has been validated to fit for simulating wave transformation in the coastal zone. Under extreme high water level and design high water level, wave fields in the calculation area of three wave types in three different return periods are simulated by using this method respectively. In addition, wave height in front of breakwater can be provided. Then the wave parameters and the mooring area of two occasions, with and without breakwater, are gained in calculation area. Based on these results, some conclusions are presented in the end.

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