Abstract

Erosion along Kavaratti Island has intensified in recent times due to infrastructure development and natural phenomenon. Numerical models were used to identify suitable foreshore protection structures, considering the near-shore coastal processes. For this purpose, shoreline change around the island was obtained from field surveys and results of the DSAS model. Subsequently, model simulations were conducted for the most appropriate use of structural protection measure to understand the change in hydrodynamics and sediment transport, which would ultimately result in stabilization of the Kavaratti Island coast. Based on the prevailing conditions, suitable site-specific coastal protection structures (e.g., groynes, revetment, breakwater, submerged geo-tubes structures and submerged breakwater) were assessed to determine the most feasible and suitable shore protection measure and observed the following: (a) Revetment and submerged geo-tube structure to be the most effective protection measures on the eastern part of the Kavaratti Island, (b) significant decrease in current speed from 0.48 to 0.05 m/s, and (c) significant decrease in wave height (from 2.5 to 0.3 m) and wave energy reduction about 50% from the prevailing conditions were observed. With this intervention, the existing shoreline of the island would at least be maintained, possibly preventing any further loss of land.

Research Highlights

1. 1.

   Net erosion rate is − 1.2 m/yr and it shows − 1.36 m/yr in the lagoon side and − 2.35 m/yr in the eastern side.

2. 2.

   Erosion hotspots are identified along the east and west coast. Highest erosion rate of − 4.23 m/yr was estimated in the eastern side of the island and on the southwest side of the chicken neck area (− 2.94 m/yr).

3. 3.

   Assessment for shoreline change predictions was carried out using Gencade model during 2018–2028.

4. 4.

   Revetment and submerged geo-tube breakwater are to be the most effective and feasible foreshore protection structure.

中文翻译：

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Lakshadweep 群岛 Kavaratti 岛沿岸海岸保护措施可行性的数值建模方法

摘要

由于基础设施的发展和自然现象，卡瓦拉蒂岛的侵蚀近来加剧。考虑到近岸海岸过程，数值模型用于确定合适的前滨保护结构。为此，从实地调查和 DSAS 模型的结果中获得了岛屿周围的海岸线变化。随后，为最恰当地使用结构保护措施进行了模型模拟，以了解水动力和沉积物输送的变化，这将最终导致 Kavaratti 岛海岸的稳定。根据当时的条件，适合特定地点的海岸保护结构（例如，防波堤、护岸、防波堤、水下土工管结构和水下防波堤）进行评估，以确定最可行和最合适的海岸保护措施，并观察到以下几点： (a) 护岸和水下土工​​管结构是 Kavaratti 东部最有效的保护措施岛，(b) 水流速度从 0.48 显着降低到 0.05 m/s，和 (c) 波高显着降低（从 2.5 到 0.3 m），并且观察到波浪能量比当时的条件减少约 50%。通过这种干预，岛上现有的海岸线至少会得到维护，可能会防止土地进一步流失。(b) 水流速度从 0.48 显着降低到 0.05 m/s，和 (c) 波高显着降低（从 2.5 到 0.3 m），并且波能比当时的条件降低了约 50%。通过这种干预，岛上现有的海岸线至少会得到维护，可能会防止土地进一步流失。(b) 水流速度从 0.48 显着降低到 0.05 m/s，和 (c) 波高显着降低（从 2.5 到 0.3 m），并且波能比当时的条件降低了约 50%。通过这种干预，岛上现有的海岸线至少会得到维护，可能会防止土地进一步流失。

研究亮点

1. 1.

   净侵蚀率为 - 1.2 m/yr，泻湖侧为 - 1.36 m/yr，东侧为 - 2.35 m/yr。

2. 2.

   沿东海岸和西海岸确定了侵蚀热点。估计岛东侧和鸡颈区西南侧的最高侵蚀率为 − 4.23 m/yr (− 2.94 m/yr)。

3. 3.

   在 2018-2028 年期间使用 Gencade 模型对海岸线变化预测进行了评估。

4. 4.

   护岸和水下土工​​管防波堤是最有效和可行的前滨保护结构。