南水北调对自然环境影响的初步研究

PRELIMINARY STUDY OF THE IMPACTS OF WATER TRANSFER FROM SOUTH TO NORTH ON NATURAL ENVIRONMENT

本文主要讨论了从长江向黄淮海平原调水对自然环境的影响。 研究水分循环和水资源的变化及与之有关的物质循环的关系,是研究跨流域调水对自然环境影响的核心问题。调水对环境影响的过程,大体可归结为如下的模式:调水→改变原有的水文情势→自然环境的变化→社会经济的变化。 任何调水工程对环境的影响,均可按地理分区方法分为水量输出区、输水通过区和水量输入区。南水北调对水量输出区的影响主要在枯水期发生在输水点附近及其下游。输水通过区主要使输水渠两侧和蓄水体周围环境受到影响。大量长江水调入黄准海平原,在一定程度上将引起黄淮海平原生态系统的变化。

The present paper mainly disses the impacts of East and Middle-Route water diversion from the Changjiang River to the Huang-Huai-Hai Plains upon natal environment.1.Studies of the changes of water circulation and water resources as well as their relationships with biocycle, atmospheric circulation and geologic process are key problems concerning the impact of inter-basin water transfer on natural environment. The process With respect to the impact of water transfer on the environment can be Summed up roughly by the following model.Water transfer→changes of the original hydrological regime→changes of thenatural environment→changes of social economy.2.The impacts of any water transfer project on the environment., according to geographic regions, may be divided into three different regions with regard to issues, namely, the water-exported region, the region through ,which water is transferred and the water-imported region.The water-exported region, With the completion of the .water transfer, influence will chiefly occur at the initial point where water starts to be exported and at the lower reaches of the river below the initial point during low-flow period.The main influence of water transfer on natural environments are as follows. Possible intensification of sea water intrusion, the acceleration of the deposition of fine particles and the expansion of bars in the Chang-jiang estuary due to the decrease of runoff of Changjiang river in low-flow periods.3.The region through which water is transferred.It mainly refers to areas on both sids of the conveyance canals as well as to the surroundings of the .water bodies of regulation and storage that are involved .Water transfer of the East route will certainly exert some influence on the water quality and aquatic ecosystems of the lakes. 4.The water-imported region: Large quantities of water diverted from Changjiang River into the Huang-Huai-Hai Plains through the middle and East Roites will inevitably cause great changes on ecosystems of the Plains. The major problems to be ackled concerning impacts of water transfer on natural environment in the water imported region are as follows. The prevention of secondary salinization and alka-lization in irrigated areas and the influence of water transfer on climate in irrigated areas and their surrounding environments.