Until 1957, the Hula Valley was covered by swampy wetlands and a shallow lake, Lake Hula. In the 1950s, the valley was drained and 6000 ha of land was converted to agricultural development. Seven years later, the Nati...Until 1957, the Hula Valley was covered by swampy wetlands and a shallow lake, Lake Hula. In the 1950s, the valley was drained and 6000 ha of land was converted to agricultural development. Seven years later, the National Water Carrier was inaugurated, granting the only natural freshwater lake in Israel, Kinneret, a national drinking water reservoir function. Agricultural cultivation in the Hula Valley faced significant challenges. A reclamation project, the “Hula Project” (HP), was implemented. Thirty (1994-2024) years of HP management are summarized. TP and TN migration data from the Hula Valley southward into Lake Kinneret was approved as not threatening its water quality. During 40 years of post-drainage period underground fire, heavy dust storms were frequently followed by soil subsidence. Nevertheless, as a result of the HP renovated management, those nuisances faded away and significantly declined. Immediately after drainage, as a result of organic Peat oxidation, a great stock of nitrates in the upper layers was formed. Since the mid-1990s, when nitrogen deficiency was developed and Cyanobacteria replaced the bloom-forming Peridinium dominancy, surplus nitrate input has not threatened Kinneret water quality. The hydrological-eco-touristic component of the reclamation project (HP), Lake Agmon-Hula (LAH) became a successful tourist attraction and also an additional nutrient source through submerged vegetation. Two Peat soil areas of land have been denied: the central and the eastern blocks. Soil moisture enhancement, especially that of the Peat soil block, initiated the lowering of the TP migration range and consequently extra water allocation was assigned for summer irrigation (the “Peat Convention Agreement”). Surface, underground seepage and river discharge flows of freshwaters from the Golan Heights into the Hula valley diluted the concentration of migrated TP concentration contributed by the eastern Peat block.展开更多
Estuarine projects can change local topography and influence water transport and saltwater intrusion.The Changjiang(Yangtze)River estuary is a multichannel estuary,and four major reclamation projects have been impleme...Estuarine projects can change local topography and influence water transport and saltwater intrusion.The Changjiang(Yangtze)River estuary is a multichannel estuary,and four major reclamation projects have been implemented in the Changjiang River estuary in recent years:the Xincun Shoal reclamation project(RP-XCS),the Qingcao Shoal reclamation project(RP-QCS),the Eastern Hengsha Shoal reclamation project(RP-EHS),and the Nanhui Shoal reclamation project(RP-NHS).The effects of the four reclamation projects and each project on the saltwater intrusion and water resources in the Changjiang River estuary were simulated in a 3D numerical model.Results show that for a multichannel estuary,local reclamation projects change the local topography and water diversion ratio(WDR)between channels and influence water and salt transport and freshwater utilization in the estuary.During spring tide,under the cumulative effect of the four reclamation projects,the salinity decreases by approximately 0.5in the upper reaches of the North Branch and increases by 0.5-1.0 in the middle and lower reaches of the North Branch.In the North Channel,the salinity decreases by approximately 0.5.In the North Passage,the salinity increases by 0.5-1.0.In the South Passage,the salinity increases by approximately 0.5 in the upper reaches and decreases by 0.2-0.5 on the north side of the middle and lower reaches.During neap tide,the cumulative effects of the four reclamation projects and the individual projects are similar to those during spring tide,but there are some differences.The effects of an individual reclamation project on WDR and saltwater intrusion during spring and neap tides are simulated and analyzed in detail.The cumulative effect of the four reclamation projects favors freshwater usage in the Changjiang River estuary.展开更多
The Caofeidian Reclamation Project has been the biggest reclamation project in China so far, in which 310 km^2 sea areas were reclaimed along the coast of Hebei Province, and it also bring about many problems and defe...The Caofeidian Reclamation Project has been the biggest reclamation project in China so far, in which 310 km^2 sea areas were reclaimed along the coast of Hebei Province, and it also bring about many problems and defects for large reclaiming area. The study focuses on the influences of the engineering exerted on evolution of the Laolonggou Lagoon with the methods of topographical measurement and surface sediment analysis. The results demonstrate that the topographical changes in the Laolonggou Lagoon had been controlled obviously by the engineering at three stages. Besides, blocking and reopening of the shoal tidal channel also affected the geological environment of the lagoon area. In the aspect of topographical change, the Laolonggou Inlet first experienced deposition after the shoal tidal channel was blocked, followed by short-time eroding for quarrying and cofferdam construction in the east, then depositing slowly after the reclaiming activity ceased, and finally eroding after the shoal tidal channel was reopened. The project, particularly cofferdam construction led to the movement of the Laolonggou Inlet axis from west to east for 50 – 100 m. In the aspect of sediment variation, the reclamation project and hydrodynamic change resulted in the variation in compositions and distribution pattern. The western lagoon area has become land mainly constituted by silt, while the sediments in the eastern area have turned finer in size. After the shoal tidal channel was reopened, the current velocity in the Laolonggou Inlet has been enhanced, making the sediments at the bottom become coarser. The sediments around the Caofeidian foreland went through a process of changing in grain size from fine to coarse and back to fine again, and the sediments are mainly constituted by silt at present.展开更多
Reclamation projects are the main method of coastal exploitation,and the hydrodynamic environmental effect,together with the sediment transport response of the reclamation project,is important to the project’s site s...Reclamation projects are the main method of coastal exploitation,and the hydrodynamic environmental effect,together with the sediment transport response of the reclamation project,is important to the project’s site selection and environmental protection.Herein,a 3D numerical model based on the finite volume community ocean model(FVCOM)is applied to simulate the changes in the Meizhou Bay’s hydrodynamic environment and sediment transport after a reclamation project.The reclamation project greatly alters the shape of the shoreline and narrows the bay,leading to a significant change in its hydrodynamic environment and sediment transport.After the project,the clockwise coastal residual current in the corner above the Meizhou Island gradually disappears.An obvious counter-clockwise coastal residual current emerges around the rectangular corner.The tidal prism decreases by 0.65×10^9 and 0.44×10^9 m^3 in the spring and neap tides,respectively.The residence time presents a major increase.These changes lead to the weakening of the water exchange capacity and the reduction of the self-purification capacity of the bay.Currents in the tidal channel weaken,whilst currents in the horizontal channel strengthen.The strength and scope of particle trajectories around the horizontal channel and the Meizhou Island enhance.The suspended sediment concentration(SSC)increases in the majority of the Meizhou Bay but decreases in the lateral bay.The eastern corner of Z2 shows a tendency to erode.The western region of the Meizhou Island,the upper portion of the rectangular corner and the western corner of Z4 show a tendency to deposit.The reclamation project increases the maximum storm surges by 0.06 m and decreases the maximum significant wave heights by 0.09 m.展开更多
文摘Until 1957, the Hula Valley was covered by swampy wetlands and a shallow lake, Lake Hula. In the 1950s, the valley was drained and 6000 ha of land was converted to agricultural development. Seven years later, the National Water Carrier was inaugurated, granting the only natural freshwater lake in Israel, Kinneret, a national drinking water reservoir function. Agricultural cultivation in the Hula Valley faced significant challenges. A reclamation project, the “Hula Project” (HP), was implemented. Thirty (1994-2024) years of HP management are summarized. TP and TN migration data from the Hula Valley southward into Lake Kinneret was approved as not threatening its water quality. During 40 years of post-drainage period underground fire, heavy dust storms were frequently followed by soil subsidence. Nevertheless, as a result of the HP renovated management, those nuisances faded away and significantly declined. Immediately after drainage, as a result of organic Peat oxidation, a great stock of nitrates in the upper layers was formed. Since the mid-1990s, when nitrogen deficiency was developed and Cyanobacteria replaced the bloom-forming Peridinium dominancy, surplus nitrate input has not threatened Kinneret water quality. The hydrological-eco-touristic component of the reclamation project (HP), Lake Agmon-Hula (LAH) became a successful tourist attraction and also an additional nutrient source through submerged vegetation. Two Peat soil areas of land have been denied: the central and the eastern blocks. Soil moisture enhancement, especially that of the Peat soil block, initiated the lowering of the TP migration range and consequently extra water allocation was assigned for summer irrigation (the “Peat Convention Agreement”). Surface, underground seepage and river discharge flows of freshwaters from the Golan Heights into the Hula valley diluted the concentration of migrated TP concentration contributed by the eastern Peat block.
基金Supported by the Science and Technology Commission of Shanghai Municipality(No.21JC1402500)。
文摘Estuarine projects can change local topography and influence water transport and saltwater intrusion.The Changjiang(Yangtze)River estuary is a multichannel estuary,and four major reclamation projects have been implemented in the Changjiang River estuary in recent years:the Xincun Shoal reclamation project(RP-XCS),the Qingcao Shoal reclamation project(RP-QCS),the Eastern Hengsha Shoal reclamation project(RP-EHS),and the Nanhui Shoal reclamation project(RP-NHS).The effects of the four reclamation projects and each project on the saltwater intrusion and water resources in the Changjiang River estuary were simulated in a 3D numerical model.Results show that for a multichannel estuary,local reclamation projects change the local topography and water diversion ratio(WDR)between channels and influence water and salt transport and freshwater utilization in the estuary.During spring tide,under the cumulative effect of the four reclamation projects,the salinity decreases by approximately 0.5in the upper reaches of the North Branch and increases by 0.5-1.0 in the middle and lower reaches of the North Branch.In the North Channel,the salinity decreases by approximately 0.5.In the North Passage,the salinity increases by 0.5-1.0.In the South Passage,the salinity increases by approximately 0.5 in the upper reaches and decreases by 0.2-0.5 on the north side of the middle and lower reaches.During neap tide,the cumulative effects of the four reclamation projects and the individual projects are similar to those during spring tide,but there are some differences.The effects of an individual reclamation project on WDR and saltwater intrusion during spring and neap tides are simulated and analyzed in detail.The cumulative effect of the four reclamation projects favors freshwater usage in the Changjiang River estuary.
基金supported by the National Natural Science Foundation of China (No. 40876033)the China Geological Survey Project (No. DD20160144)。
文摘The Caofeidian Reclamation Project has been the biggest reclamation project in China so far, in which 310 km^2 sea areas were reclaimed along the coast of Hebei Province, and it also bring about many problems and defects for large reclaiming area. The study focuses on the influences of the engineering exerted on evolution of the Laolonggou Lagoon with the methods of topographical measurement and surface sediment analysis. The results demonstrate that the topographical changes in the Laolonggou Lagoon had been controlled obviously by the engineering at three stages. Besides, blocking and reopening of the shoal tidal channel also affected the geological environment of the lagoon area. In the aspect of topographical change, the Laolonggou Inlet first experienced deposition after the shoal tidal channel was blocked, followed by short-time eroding for quarrying and cofferdam construction in the east, then depositing slowly after the reclaiming activity ceased, and finally eroding after the shoal tidal channel was reopened. The project, particularly cofferdam construction led to the movement of the Laolonggou Inlet axis from west to east for 50 – 100 m. In the aspect of sediment variation, the reclamation project and hydrodynamic change resulted in the variation in compositions and distribution pattern. The western lagoon area has become land mainly constituted by silt, while the sediments in the eastern area have turned finer in size. After the shoal tidal channel was reopened, the current velocity in the Laolonggou Inlet has been enhanced, making the sediments at the bottom become coarser. The sediments around the Caofeidian foreland went through a process of changing in grain size from fine to coarse and back to fine again, and the sediments are mainly constituted by silt at present.
基金This study was funded by the National Natural Science Foundation of China(Grant Nos.51779039 and 51879028).
文摘Reclamation projects are the main method of coastal exploitation,and the hydrodynamic environmental effect,together with the sediment transport response of the reclamation project,is important to the project’s site selection and environmental protection.Herein,a 3D numerical model based on the finite volume community ocean model(FVCOM)is applied to simulate the changes in the Meizhou Bay’s hydrodynamic environment and sediment transport after a reclamation project.The reclamation project greatly alters the shape of the shoreline and narrows the bay,leading to a significant change in its hydrodynamic environment and sediment transport.After the project,the clockwise coastal residual current in the corner above the Meizhou Island gradually disappears.An obvious counter-clockwise coastal residual current emerges around the rectangular corner.The tidal prism decreases by 0.65×10^9 and 0.44×10^9 m^3 in the spring and neap tides,respectively.The residence time presents a major increase.These changes lead to the weakening of the water exchange capacity and the reduction of the self-purification capacity of the bay.Currents in the tidal channel weaken,whilst currents in the horizontal channel strengthen.The strength and scope of particle trajectories around the horizontal channel and the Meizhou Island enhance.The suspended sediment concentration(SSC)increases in the majority of the Meizhou Bay but decreases in the lateral bay.The eastern corner of Z2 shows a tendency to erode.The western region of the Meizhou Island,the upper portion of the rectangular corner and the western corner of Z4 show a tendency to deposit.The reclamation project increases the maximum storm surges by 0.06 m and decreases the maximum significant wave heights by 0.09 m.