近50年民勤绿洲生态环境演变及综合治理对策

 50年来,由于人类活动对水、土、植被等资源的强烈干扰,民勤绿洲的生态环境发生了巨大的变化,主要表现为:地表水资源减少,水量从20世纪50年代的4.5亿m3减少到90年代的0.89亿m3;地下水量过度开采,水位下降,从20世纪50年代的1.5～2.0m下降到80年代的5.0 m,90年代的16.4m;水质污染,矿化度升高;天然和人工植被衰退,物种多样性减少,植被向旱生方向演替;土壤旱化加剧,土地荒漠化严重等。为探索解决这一系列问题,在定量分析长期野外观测资料的基础上,主要分析了近50年来民勤绿洲水资源变化过程及其态势以及水资源的不合理利用所引起的一系列生态环境变化,同时提出主要治理途径:1)以流域为单元,通过法律、行政和经济手段强化水资源管理;2)通过节水技术应用,发展节水型农业和建立节水型社会;3)增加外流域调水量,满足生态环境用水需求;4)实施适度移民,实现人与自然和谐发展;5)运用生物和工程措施,综合防治荒漠化,整治土壤盐渍化。

Succession of ecological environment in the last 50 years in Minqin Oasis of Gansu province and its comprehensive controlling countermeasures

Under the dramatic influence of artificial factors on water,land and vegetation resources during the recent half a century,a series of great changes in eco-environment have taken place in Minqin oasis of Gansu province on such facets as the reduction of surface runoff amounts from 4.5×108m³ in 1950s to　0.89×108?m³ in 1990s in the lower reaches of Shiyang river,groundwater overexploitation causing decrease of groundwater level from average 1.52m in 1950s to 5?m in 1980s and 16.4m in 2002,increase of groundwater mineralization,degradation of natural and artifical vegetation,reduction of species diversity and succession of vegetation from hygrophilous vegetation series to xerophilous vegetation series,and the enlarge of land salinization area,serious land desertification,etc.Variation process of water resources and current situations are analyzed,as well as the irrational water utilization causing a series of ecological environment variation.Based on this analysis,some countermeasures to resources sustainable utilization and ecological protection were put forth in Minqin oasis for the purpose of harmonious development of ecology,society and economy.Tightening up the management of water resources through administration,economic and law means,applying water-saving irrigation methods so as to set up water-saving agriculture system,increasing the surface water amount from outer range for eco-environmental water demand,moving out a part of farmers to implement the harmonious development of mankind and nature,controlling the desertification land and reclaiming saline soil through the biological and mechanical methods are the main controlling measures to improve this situation.