Seasonal variation in longshore sediment transport rate and its impact on sediment budget along the wave-dominated Karnataka coast, India,Journal of Earth System Science

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Seasonal variation in longshore sediment transport rate and its impact on sediment budget along the wave-dominated Karnataka coast, India
Journal of Earth System Science ( IF 1.9 ) Pub Date : 2020-11-21 , DOI: 10.1007/s12040-020-01504-y
Ateeth Shetty , K S Jayappa

Abstract

The Karnataka coast is subjected to high wave activity during the southwest monsoon when most of the sandy beaches undergo erosion. Based on the littoral cell concept, the Karnataka coast is broadly divided into 14 major littoral cells and 26 stations are selected in the present study. WaveWatch III global wave model data at 0.5° interval were used to derive the nearshore wave characteristics from XBeach numerical model. The model results were validated with the measured wave rider buoy data of the Indian National Centre for Ocean Information Services. The beach orientation, nearshore slope, median sediment size, significant wave height, mean wave direction, and the peak wave period were used in the estimation of longshore sediment transport rate. The mean significant wave height along the Karnataka coast was about 0.86 m, wave direction was about 210° and peak wave period was about 13 sec. The wave height during southwest monsoon (June–September) was higher, post-monsoon (October–December) was moderate and pre-monsoon (January–May) was the calmest period. Direction of longshore sediment transport was southwards during pre- and post-monsoons when waves were from the south–southwest. Whereas, northwards during monsoon when the wave approach from west–southwest to west. The annual net longshore sediment transport rate estimated was about 0.65×10⁶ m³ towards the south and the sediment budget investigation depicts the loss of 0.067×10⁶ m³ during the study period.

Highlights

WaveWatch III global wave model data at 0.5° interval were used as input to derive the nearshore wave characteristics from XBeach numerical model.
The wave height during southwest monsoon (June to September) was higher, post-monsoon (October to December) was moderate and pre-monsoon (January to May) was the calmest period.
Direction of longshore sediment transport was southwards during pre- and post-monsoons when waves were from the south-southwest. Whereas, northwards during monsoon when the wave approach from west-southwest to west.
The annual net longshore sediment transport rate estimated was about 0.65×10⁶ m³ towards the south, and the sediment budget investigation depicts the loss of 0.067×10⁶ m³ during the study period.

中文翻译：

沿波为主的印度卡纳塔克邦沿海沿岸沉积物运移速率的季节性变化及其对沉积物收支的影响

摘要

当大多数沙滩遭受侵蚀时，卡纳塔克邦海岸在西南季风期间遭受高波活动。根据沿海沿岸概念，卡纳塔克邦海岸大致分为14个主要沿岸沿岸单元，本研究选择了26个站。以0.5°间隔的WaveWatch III整体海浪模型数据从XBeach数值模型中得出近岸海浪特征。利用印度国家海洋信息服务中心测得的波浪骑士浮标数据验证了模型结果。沿海滩的方向，近岸坡度，中值沉积物尺寸，有效波高，平均波向和波峰周期被用于估算近岸沉积物的输送速度。卡纳塔克邦沿海平均波高约为0.86 m，波方向约为210°，峰值波周期约为13秒。西南季风（6月至9月）的浪高较高，季风后（10月至12月）的浪高适中，季风前（1月至5月）是最平静的时期。在季风前后，当波浪来自西南偏南时，沿岸沉积物的运输方向是向南。而在季风期间，当海浪从西西南偏西时，则向北。估计年净近岸沉积物输送速率约为0.65×10 在季风前后，当波浪来自西南偏南时，沿岸沉积物的运输方向是向南。而在季风期间，当海浪从西西南偏西时，则向北。估计年净近岸沉积物输送速率约为0.65×10 在季风前后，当波浪来自西南偏南时，沿岸沉积物的运输方向是向南。而在季风期间，当海浪从西西南偏西时，则向北。估计年净近岸沉积物输送速率约为0.65×10向南⁶ m ³，沉积物预算调查显示在研究期间损失了0.067×10 ⁶ m ³。