人工输水对石羊河下游青土湖区域生态环境的影响分析

通过对石羊河下游青土湖人工输水后水面形成区环境要素变化的调查研究,分析了水面形成对区域地下水位、植被、大气温湿度、风速等的影响。结果表明:(1)由于输水方式、输水时间集中等因素影响,区域水面形成快速;且每个输水周期完成6个月后的区域保留水面积持续增大,4a间水面积增加4.52倍,面积扩大的叠加效应明显。(2)输水作用和水面的形成,促使输水区域地下水埋深由6m,提升到0.6—3.2m。(3)水面形成促进了区域以白刺为代表的单一荒漠植被群落向芦苇草甸、盐化草甸等多样化群落演替。(4)水面形成的"冷岛效应"明显,促进了区域小气候环境的改善;输水区500m范围平均温度降低55.67%,湿度增加3倍。人工输水对青土湖区域生态环境的改善产生了明显的积极作用,但输水政策的持续性、输水策略调整等不确定性影响,以及水面形成对局部范围风沙活动、植物物种多样性等方面的负面影响值得关注和深入研究。

Influence analysis of artificial water transfer on the regional ecological environment of Qingtu Lake in the lower reaches of the Shiyang River

This paper uses sample collection and position observation to survey and study changes of environmental elements in the aspect of 2010-2014 subterranean stage, vegetation, and narrow-scope climate of water-surface formation area for sake of making a quantitative assessment towards the effects of the regional ecological environment supplied water manually from Qingtu Lake off Shiyang River. In addition, the paper also analyzes the situation of water surface, depth of ground water at different time intervals, landscape structure of vegetation, species composition of vegetation community, and changes of quantity, air temperature, moisture, and wind speed. Some ecological factors were explored to respond to water surface formation. The findings show that (1) water surface becomes fast due to different delivery patterns and the duration of water delivery. Regional reserved water area increases to 6 months after each delivery, 4a water area increases by 4.52 times, the superimposed effect of area enlargement were apparent. (2) Water surface area increase and water delivery enlarges the regional ground water from 0.6 to 3.2m. The coefficient of association of reserved water area and ground water depth is 0.909. (3) The structure of original typical desert vegetation changed significantly after water body formation. Water body changes the regional plant community from a simple desert vegetation type before the water delivery, primarily dominated by Nitraria tangutorum Bobr, into reed meadows and salinized meadows around water surface. (4) Because of the formation of a water body and regional vegetation, a cold-island effect was evident during the present study, which improved the regional climate. The mean temperature 500m around water body decreased by 55.67%, and the humidity tripled. The influence of the water surface formation on wind speed was evident, which strengthened the surface erosion of the water surface. Artificial water delivery greatly improved the regional ecological environment of Qingtu Lake; however, due to the uncertainty of water delivery policy and its adjustment strategy, the relevant negative effects of blown sand and regional diversity of species should be addressed in future research.