Coastal erosion dynamics and storm characteristics of Bykovsky Peninsula

This study investigates the rate of erosion during the 1951-2006 period on the Bykovsky Peninsula, located north-east of the harbour town of Tiksi, north Siberia. Its coastline, which is characterized by the presence of ice-rich sediment (Ice Complex) and the vicinity of the Lena River Delta, retreated at a mean rate of 0.59 m/yr between 1951 and 2006. Total erosion ranged from 434 m of erosion to 92 m of accretion during these 56 years and exhibited large variability (sigma = 45.4). Ninety-seven percent of the rates observed were less than 2 m/yr and 81.6% were less than 1 m/yr. No significant trend in erosion could be recorded despite the study of five temporal subperiods within 1951-2006. Erosion modes and rates actually appear to be strongly dependant on the nature of the backshore material, erosion being stronger along low-lying coastal stretches affected by past or current thermokarst activity. The juxtaposition of wind records monitored at the town of Tiksi and erosion records yielded no significant relationship despite strong record amplitude for both data sets. We explain this poor relationship by the only rough incorporation of sea-ice cover in our storm extraction algorithm, the use of land-based wind records vs. offshore winds, the proximity of the peninsula to the Lena River Delta freshwater and sediment plume and the local topographical constraints on wave development.

本研究针对西伯利亚北部港口城镇提克西东北侧的别科夫斯基半岛，探究了1951—2006年间的海岸侵蚀速率。该半岛海岸以富冰沉积物（Ice Complex）为特征，且毗邻勒拿河三角洲，1951至2006年间的平均后退速率为0.59米/年。56年间总侵蚀量介于434米侵蚀与92米淤积之间，波动幅度极大（标准差σ=45.4）。观测到的侵蚀速率中，97%低于2米/年，81.6%低于1米/年。尽管对1951—2006年间的5个时间子时段开展了分析，仍未观测到侵蚀速率存在显著趋势。实际上，侵蚀模式与速率强烈依赖于后滨物质的性质：受既往或现今热喀斯特活动影响的低洼海岸段，侵蚀强度更高。将提克西镇的风速观测记录与海岸侵蚀记录进行比对后，未发现二者存在显著相关性，尽管两组数据集的波动幅度均较大。我们将这种相关性偏弱的原因归结为：风暴提取算法中仅粗略纳入了海冰覆盖因素、采用陆上风速记录而非离岸风速记录、该半岛毗邻勒拿河三角洲的淡水与沉积物羽流，以及局地地形对波浪发育的限制作用。