黑河流域不同类型土地沙漠化驱动力分析

 在分析黑河流域土地沙漠化历史和现状的基础上得出造成黑河流域土地沙漠化发生、发展的原因,除了该区脆弱的生态环境:蒸发量大,干旱多风,降水极少,地表组成物质疏松等自然因素外,主要是人类不合理的经济活动,导致流域内有限的水资源不能合理利用,从而使得中上游用水量大幅度增加,造成下游水资源的枯竭,致使地表植被因缺水、过度樵采和放牧而大量死亡,引起土地沙漠化的发生。同时,干旱区绿洲的地形地貌条件对于绿洲的兴衰和发展有重要影响,自然灾害是由于某种作用超出了人类所能承受的能力,对人类的生存与发展造成巨大的威胁和损害。河流改道是绿洲废弃的最直接原因之一。战争导致的农牧业更替也是绿洲演变的一个因素,同时战争对农田水利设施的破坏性也是巨大的。政策导向可以影响到绿洲人口的迁入和迁出,绿洲规模的扩大与缩小,绿洲内部结构、功能、性质的变化,以及对整个流域资源的管理和利用,对于绿洲的影响具有显著的时效性。总之,黑河沙漠化土地形成是在气候暖干化条件下,不合理的人为活动同脆弱的环境、贫乏的水、土、生物资源之间不相协调的产物,是涉及自然、社会、经济等多因子共同作用的综合过程。过度的人为活动是沙漠化的主导驱动因素。

Driving Forces of Different Type of Land Desertification in Hiehe River Basin

The history and present status of land desertification in Heihe river basin were analyzed. It was proved that the main cause of desertification forming and developing was irrational human economic activities, besides natural factors, such as such as fragile eco-environment, high evaporation, arid and windy climate, sparse precipitation and loose surface materials, etc. Irrational use of limited water resources has resulted in the overuse of water resource in the upstream basin, consequently, the downstream basin was short with water shortage, the vegetation degraded. In the long term land development processes, human economic activities severely disturbed the hydrological cyclic processes, caused a series of hydrological effect and eco-environmental changes: some lakes dwindled or dried up, river cannel shifted, discharge and salinity changed and land desertification took place. The geomorphologic conditions of arid oasis also affect oasis development. Natural disasters are often beyond man's control power and pose serious threat to human existence and development. The channel relocation is often a direct cause for the abandonment of oases. Wars also caused the alternation of farming and grazing and destroyed the farmland water projects. Policies could affect the immigration and emigration of people, the expansion or shrinkage of oases and the oasis structure and function, the management and use of water resources. In other word policy has a significant real-time effect on the oases. In a word, both the natural driving forces and human driving force play a great role in the desertification of the oasis but human activity is the leading factor.