南水北调西线工程对黄河流域生态环境的影响分析

Impact of Project of Water Diversion from South to North Via Western Course to Ecological Environment in Yellow River Basin

黄河流域地处我国北方干旱和半干旱地区,水资源贫乏,人均占有水资源仅为全国平均水平的1/3,森林覆盖率仅为6%,是全国平均水平的50%。水土流失严重,中上游土壤侵蚀模数一般在5000t/(km2.a)以上。黄河含砂量居世界之最,多年平均含砂量达33kg/m3,由于水资源量的逐年减少和需求量的逐年增大,引起了土地沙漠化,沙尘暴以及黄河水质恶化等一系列环境问题。南水北调西线工程拟从水量充沛的长江、澜沧江、怒江流域调部分水量进入黄河,总调水量170亿m3。其中用于农、林、牧业方面的灌溉水量占总调水量的55%,可以有效地增加植被和控制水土流失,遏制土壤沙漠化;能够缓解黄河水资源的供需矛盾,改善黄河水质;同时还可以增加黄河下游河道的冲刷长度,减少泥沙淤积,有利于黄河下游河道的稳定性。

The Yellow River basin is located in arid and semi-arid region of the northern of our country. In here the water resource is poor. The per capita water resource is only 1/3 of the average national level. The forest coverage rate is only 6%. It is 50% of the average national level. Water and soil erosion are serious. On the Middle and Upper of the Yellow Rive, the soil erosion modulus is generally above 5000 t/（km^2 ·a）. The sand content of the Yellow River occupies the first in the world. Average sand content of many years have reached 33 kg/m^3.The reduction of water resource quantity and Increase of demand year by year have caused a series of environmental questions, such as the land desertification, the sandstorm and the Yellow River water＇s deterioration, etc. Project of Water Diversion from the South to the North Via the Western Course is transforms some water from Changjiang River, Lancangjiang River, Nujiang River basin of water yield plentiful to the Yellow River. The amount of water yield 17 billion m^3 The water amount of irrigation among them is used in agriculture, forest, animal husbandry occupies 55 % of water quantity. It can increase vegetation, controlling water and soil erosion and contain the soil desertification. It can alleviate the imbalance between supply and demand of the water resource of the Yellow River, and improve the water quality of the Yellow River. At the same time, they can increase the length of eroding of the downstream river of the Yellow River and reduce the silt to deposit. It is favorable to the stability of the downstream river of the Yellow River.