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
China has many lakes, marshlands and rivers. Due to their uneven geographical distribution and varied degrees of salinity, their exploitable freshwater resources are limited. In the wake of the highspeed growth of nat...China has many lakes, marshlands and rivers. Due to their uneven geographical distribution and varied degrees of salinity, their exploitable freshwater resources are limited. In the wake of the highspeed growth of national economy in recent years, human infringement upon their natural settings has been increasingly intense, leading to the degeneration of China's lacustrine ecosystems and the degradation of their surrounding environments. Lakes are shrinking and becoming more saline. In arid and semi-arid inland areas, some of them have even disappeared. In addition, lake water pollution and eutrophication in densely populated areas are getting worse, resulting in serious water shortages in some places. Silt deposition in lake basins, water surface shrinkage caused by hectic and irrational reclamation for farmland, the prevalence of flooding and water-logging calamities and ecosystem depletion caused by predatory exploitation of fishery resources, all of these have become restrictive factors in regional sustainable development. The author of this article suggests measures for the protection and sustainable exploitation of limnetic settings in China.展开更多
The changes that have taken place in Nigerian fisheries are reviewed. Artisanal fishery has continued to dominate the fisheries,contributing over 85% of total fish production. The inland water and coastal seas are ful...The changes that have taken place in Nigerian fisheries are reviewed. Artisanal fishery has continued to dominate the fisheries,contributing over 85% of total fish production. The inland water and coastal seas are fully exploited and the increase in fishery production is not likely. Aquaculture potentials remain untapped as much as deep-sea fisheries. The combined potential of the fisheries resources-freshwater,marine and aquaculture can meet over 90% of the nation's demand for fish. Opportunities for invest-ments,therefore,exist in the various subsectors,especially in the areas of storage,processing and preservation for the capture fishery and fish seed multiplication for aquaculture.展开更多
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.
文摘China has many lakes, marshlands and rivers. Due to their uneven geographical distribution and varied degrees of salinity, their exploitable freshwater resources are limited. In the wake of the highspeed growth of national economy in recent years, human infringement upon their natural settings has been increasingly intense, leading to the degeneration of China's lacustrine ecosystems and the degradation of their surrounding environments. Lakes are shrinking and becoming more saline. In arid and semi-arid inland areas, some of them have even disappeared. In addition, lake water pollution and eutrophication in densely populated areas are getting worse, resulting in serious water shortages in some places. Silt deposition in lake basins, water surface shrinkage caused by hectic and irrational reclamation for farmland, the prevalence of flooding and water-logging calamities and ecosystem depletion caused by predatory exploitation of fishery resources, all of these have become restrictive factors in regional sustainable development. The author of this article suggests measures for the protection and sustainable exploitation of limnetic settings in China.
文摘The changes that have taken place in Nigerian fisheries are reviewed. Artisanal fishery has continued to dominate the fisheries,contributing over 85% of total fish production. The inland water and coastal seas are fully exploited and the increase in fishery production is not likely. Aquaculture potentials remain untapped as much as deep-sea fisheries. The combined potential of the fisheries resources-freshwater,marine and aquaculture can meet over 90% of the nation's demand for fish. Opportunities for invest-ments,therefore,exist in the various subsectors,especially in the areas of storage,processing and preservation for the capture fishery and fish seed multiplication for aquaculture.
