南水北调东线沿线土壤盐渍化初步分析

PRELIMINARY ANALYSIS ON SOIL SALINIZATION ALONG THE PROPOSED EAST ROUTE IN SOUTH-TO-NORTH WATER TRANSFER PROJECT

本文简要分析了南水北调东线输水工程实施后可能引起黄淮海平原土壤次生盐渍化的原因,并提出了相应的防止措施。

The South-to-north water transfer is a magnificent project in China, which brings excess water from the Yangtze River in the south to the arid areas of North and Northwest China. The proposed East Transfer Route would pass through and supply water to the Huang-Huai-Hai plain,The liuang-Huai-Hai plain is a weakly or easily salinized region . Owing to the influence of the pacific monsoon, this region has always been suffered from disasters of drought, flooding, salinization and alkalization throughout the history. Under this specific natural condition and human activity , sail salt-water movement is significantly characterized by seasonal changes. Soil is in the process of modern salinization,only varying in degrees of salt accumulation with location and times. Therefore, in the design and implement of the South-to-north Water Transfer, attention should be paid to the control of soil salinization .Alter the water is transferrer, the irrigation area in the Huang-Huai-Hai plain will be enlarged. There will be a beneficial effect on improving water condition of this region, leaching soil salt and promoting agricultural production. At the same time, the present salt-water balance of the region will be changed. The districts with poor natural drainage and without artifical drainge system might be confronted with secondary soil salinization.If the four lakes in the south of the Huang-He are used as regulation reservoirs in the South-to north Water Transfer project, then the elevation of the original storage level of the lakes will have a definite effect on the drainage of the main channels in the west of the four lakes and on soil salinization.From a long-term point of view, it is necesary to dig deep trough or to deepen the bottom of the lakes to meet the requirment of storage capacity and storage level of the lakes. In addition, the channel of drainage flooding and controlling seepage should be excavated along the west side of the four lakes, to reduce and control groundwater level of the region along the lakes, at the same time, pumping drainage station should be established at the outlet of the main drainage channel, to settle drainage outlet and increase capacity of drainage flooding.The conveyance of water for a long period of time in the main canals, especially in the stretches where the level of transported water is higher than the land surface, would lead to the formation of high-water-table zones on both sides of the canals, owing to a large amount of seepage of canals. The groundwater runoff in the left side of the main canals would impede in varying degrees and block the drainage of underground runoff and might lead to a general increase of the level of groundwater and aggravate soil salinization along the canal. Both an adequate engineering drainage system of controlling or intercepting seepage and an agricultural technique should be considered. At the same time, a scientific management system for the supply of transferred water should be worked out. So long as more attention is paid and appropriate and reasonable measures of water management, agricultural and engineering system are adopted, soil salinization could be prevented or controlled.