Based on high-tide shoreline data extracted from 87 Landsat satellite images from 1986 to 2019 as well as using the linear regression rate and performing a Mann-Kendall(M–K)trend test,this study analyzes the linear c...Based on high-tide shoreline data extracted from 87 Landsat satellite images from 1986 to 2019 as well as using the linear regression rate and performing a Mann-Kendall(M–K)trend test,this study analyzes the linear characteristics and nonlinear behavior of the medium-to long-term shoreline evolution of Jinghai Bay,eastern Guangdong Province.In particular,shoreline rotation caused by a shore-normal coastal structure is emphasized.The results show that the overall shoreline evolution over the past 30 years is characterized by erosion on the southwest beach,with an average erosion rate of 3.1 m/a,and significant accretion on the northeast beach,with an average accretion rate of 5.6 m/a.Results of the M–K trend test indicate that significant shoreline changes occurred in early 2006,which can be attributed to shore-normal engineering.Prior to that engineering construction,the shorelines are slightly eroded,where the average erosion rate is 0.7 m/a.However,after shore-normal engineering is performed,the shoreline is characterized by significant erosion(3.2 m/a)on the southwest beach and significant accretion(8.5 m/a)on the northeast beach,thus indicating that the shore-normal engineering at the updrift headland contributes to clockwise shoreline rotation.Further analysis shows that the clockwise shoreline rotation is promoted not only by longshore sediment transport processes from southwest to northeast,but also by cross-shore sediment transport processes.These findings are crucial for beach erosion risk management,coastal disaster zoning,regional sediment budget assessments,and further observations and predictions of beach morphodynamics.展开更多
South of Hangzhou Bay, Zhejiang Province, exhibits an embayed muddy coastline, with the muddy beaches of embayments extending continuously seaward.The source of sediments on this coast presents an interesting problem ...South of Hangzhou Bay, Zhejiang Province, exhibits an embayed muddy coastline, with the muddy beaches of embayments extending continuously seaward.The source of sediments on this coast presents an interesting problem to marine geologists and geomorphologists .The total annual load of sediments from the rivers of Zhejiang is only 12×106t.These materials affect only the area near the river mouths. The paper showed that the sediment along the coast of Zhejiang mainly comes from the Changjiang Estuary through analysing the time and space variations of suspended sediment, the features of sediment and the sedimentary transport.The Changjiang River is the largest river system in China, its sediment to the sea amounting to 468×106t. The sediment during summer transports mainly eastward, and is affected by the water body with high temperature, salinity and transparency; the winter season is the period with high sediment concentration. The sediment of the Changjiang Estuary transports together with the longshore current of the East China Sea southward, the southern boundary can reach the sea region approximately 500 km from the Shacheng Harbour. The accretion rate seaward has been about 10 - 30 m since the 16th century. The sediment movement combined the longitudinal with the lateral, so that the muddy flats progress continuously seaward under the construction of the seashore profile .展开更多
The discovery of useful brine resources in the embayed coastal zone of Qingdao is an important achievement in research on potential underground brine resources stored in Quatemary littoral facies in the North China co...The discovery of useful brine resources in the embayed coastal zone of Qingdao is an important achievement in research on potential underground brine resources stored in Quatemary littoral facies in the North China coast. The Holocene transgression in this area provided the ancient seawater sources for forming brine. In spite of the unfarorable geological conditions (narrow littoral plain. shallow and thin Quatemary sedimentary strata) Qingdao’s embayed coast has deposition basins with bay-in-bay and weir dam ideal for gathering brine. The geologic structure of the littoral Quatemary deposition basin and hydrologic condition(deficient runoff) comprise favorable environment for the formation and abundance of underground brine.The embayed coast geomorphy controls the distribution of brine in patches that form small mineral zones in some parts. The brine aquifer whiment series formed under Quatemary littoral plain sedimentary and hydrogeologic environment are usually single phreatic ones. Part of the thick deposit areas consists of phreatic and poorly confined aquifers. Near the river mouth, there can someimes be brine aquifers interbeded with saline water ones. The basement of the brine ore deposits is comprised of Mesozoic rock formations. Underground brine is scattered almost all over the littoral plain and only in the larger plain’s area is the narrow saline water belt distributed beyond the brine zone. The structural features of the brine aquifer sediment series along the Jiaozhou Bay Coast are typical of those in the North China coast. We name it"Jiaozhou Bay Type" Its features are different from those of other brine aquifer sediment series such as "Laizhou Bay Type" and"Bohai Bay Type" in the littoral plain of the Bohai Sea.展开更多
基金The National Nature Science Foundation of China under contract No.42071007the Nature Science Foundation of Hainan Province under contract Nos 422RC665,421QN0883,and 423RC553。
文摘Based on high-tide shoreline data extracted from 87 Landsat satellite images from 1986 to 2019 as well as using the linear regression rate and performing a Mann-Kendall(M–K)trend test,this study analyzes the linear characteristics and nonlinear behavior of the medium-to long-term shoreline evolution of Jinghai Bay,eastern Guangdong Province.In particular,shoreline rotation caused by a shore-normal coastal structure is emphasized.The results show that the overall shoreline evolution over the past 30 years is characterized by erosion on the southwest beach,with an average erosion rate of 3.1 m/a,and significant accretion on the northeast beach,with an average accretion rate of 5.6 m/a.Results of the M–K trend test indicate that significant shoreline changes occurred in early 2006,which can be attributed to shore-normal engineering.Prior to that engineering construction,the shorelines are slightly eroded,where the average erosion rate is 0.7 m/a.However,after shore-normal engineering is performed,the shoreline is characterized by significant erosion(3.2 m/a)on the southwest beach and significant accretion(8.5 m/a)on the northeast beach,thus indicating that the shore-normal engineering at the updrift headland contributes to clockwise shoreline rotation.Further analysis shows that the clockwise shoreline rotation is promoted not only by longshore sediment transport processes from southwest to northeast,but also by cross-shore sediment transport processes.These findings are crucial for beach erosion risk management,coastal disaster zoning,regional sediment budget assessments,and further observations and predictions of beach morphodynamics.
文摘South of Hangzhou Bay, Zhejiang Province, exhibits an embayed muddy coastline, with the muddy beaches of embayments extending continuously seaward.The source of sediments on this coast presents an interesting problem to marine geologists and geomorphologists .The total annual load of sediments from the rivers of Zhejiang is only 12×106t.These materials affect only the area near the river mouths. The paper showed that the sediment along the coast of Zhejiang mainly comes from the Changjiang Estuary through analysing the time and space variations of suspended sediment, the features of sediment and the sedimentary transport.The Changjiang River is the largest river system in China, its sediment to the sea amounting to 468×106t. The sediment during summer transports mainly eastward, and is affected by the water body with high temperature, salinity and transparency; the winter season is the period with high sediment concentration. The sediment of the Changjiang Estuary transports together with the longshore current of the East China Sea southward, the southern boundary can reach the sea region approximately 500 km from the Shacheng Harbour. The accretion rate seaward has been about 10 - 30 m since the 16th century. The sediment movement combined the longitudinal with the lateral, so that the muddy flats progress continuously seaward under the construction of the seashore profile .
文摘The discovery of useful brine resources in the embayed coastal zone of Qingdao is an important achievement in research on potential underground brine resources stored in Quatemary littoral facies in the North China coast. The Holocene transgression in this area provided the ancient seawater sources for forming brine. In spite of the unfarorable geological conditions (narrow littoral plain. shallow and thin Quatemary sedimentary strata) Qingdao’s embayed coast has deposition basins with bay-in-bay and weir dam ideal for gathering brine. The geologic structure of the littoral Quatemary deposition basin and hydrologic condition(deficient runoff) comprise favorable environment for the formation and abundance of underground brine.The embayed coast geomorphy controls the distribution of brine in patches that form small mineral zones in some parts. The brine aquifer whiment series formed under Quatemary littoral plain sedimentary and hydrogeologic environment are usually single phreatic ones. Part of the thick deposit areas consists of phreatic and poorly confined aquifers. Near the river mouth, there can someimes be brine aquifers interbeded with saline water ones. The basement of the brine ore deposits is comprised of Mesozoic rock formations. Underground brine is scattered almost all over the littoral plain and only in the larger plain’s area is the narrow saline water belt distributed beyond the brine zone. The structural features of the brine aquifer sediment series along the Jiaozhou Bay Coast are typical of those in the North China coast. We name it"Jiaozhou Bay Type" Its features are different from those of other brine aquifer sediment series such as "Laizhou Bay Type" and"Bohai Bay Type" in the littoral plain of the Bohai Sea.
