三峡工程对长江河口地区土壤水盐动态的影响

Impact of Three-Gorge Project on the Dynamic of Soil Water and Salt in the Yangtze River Estuarine Region

长江河口地区地势低平,长期以来涝渍和盐碱一直是本区农业生产发展的潜在威胁。三峡工程建成后,由于三峡水库对长江流量的季节性调蓄,将影响河口地区的土壤水盐动态,其影响关系较为复杂。数值模拟综合结果表明:秋季积盐量大于春季脱盐量;影响程度由河口沿江向上逐渐减弱,离海越近,影响程度越大;从横向上来看,离江越近,影响程度越大,特别是距江4km范围内的区域,土壤产生积盐和次生盐渍化的可能性更大。

The topography is low and flat in the estuarine region of the Yangtze River, where waterlog and soil salinity have been all through latent threats to the agricultural development for a long time. After the Three-Gorge Project is built up, the Three-Gorge Reservoir will have impact on the dynamic of soil water and salt in the region because of its adjustment effects on of the discharge in the Yangtze River seasonally. These influences are very complicated. It is shown through numeric simulation that in spring the soil will desalt, and in autumn the soil will accumulate salt; the amount of salt accumulated in the autumn is greater than that desalted in spring, The impact degree of the project on the regime of soil salt will be gradually weakened along the river up from the estuary, the nearer to the sea, the greater the impact; in cross-sectional profiles, the nearer to the river, the significant the impact. Especially within the range of 4 km from the river, it is more possible that soil will accumulate salt and induce secondary salinization.