新疆和田绿洲耕地阈值预估

目的]在西北干旱区，因开垦耕地，绿洲不断扩张，挤占了生态用水，引起一系列生态与环境问题。以和田绿洲为例，用定量方法计算耕地面积阈值，可为当地水土资源开发及生态保护提供理论依据。方法]水土平衡法。结果]结果表明，P=75%时，2010、2020、2030年和田绿洲的耕地面积阈值分别为13.83×104、16.78×104、16.50×104 hm2；P=50%时，2010、2020、2030年和田绿洲的耕地面积阈值分别为14.95×104、18.08×104、17.78×104 hm2。如果不采取有效措施控制耕地扩张，2020、2030年耕地面积将分别超过P=75%时耕地面积阈值2.78×104 hm2、5.07×104 hm2。即使采取高效节水技术，2020年及2030年种植业需水量将由2010年的19.77×108 m3增加到20.82×108、21.95×108 m3，生态需水量及入塔里木河水量将无法得到保证，这必将危及和田河流域，甚至塔里木河流域的生态系统安全与稳定。结论]耕地超过耕地阈值时，不仅危及和田绿洲的生态安全，同时因耕地扩张加大水资源消耗，和田河汇入塔里木河水量减少，威胁着塔里木河生态与环境安全。为此建议制定严格措施，加强干旱区绿洲-荒漠过渡带的保护，严禁以各种名义的开荒。

The Estimation of Cultivated Land Threshold Value in Hotan Oasis

Objective] Water shortage is a key natural factor limiting arid economic development and ecological security. However, the large-scale land reclamation ag-ainst natural laws has been speeding up water consumption, and the ecological wa-ter use which is the primary condition for maintaining ecological security was squeezed. Moreover, the fragile oasis ecosystem would be destroyed dramatical y. In order to maintain ecological security, it is urgent to evaluate the threshold value of cultivated land. Method] The method of water-soil balance was used to evaluate the threshold value of cultivated-land on the premise of al ocating downstream eco-logical water demand. Result] Under the frequency of 75% (P=75 for short) in Hotan River, the threshold value of cultivated-land in Hotan Oasis would be 13.83 × 104, 16.78×104 and 16.50×104 hm2 in 2010, 2020 and 2030 respectively. Under the frequency of 50% (P=50 for short), the threshold value of cultivated land in Hotan Oasis would be 14.95 ×104, 18.08 ×104 and 17.78 ×104 hm2 in 2010, 2020 and 2030 respectively. If effective measures are not taken to control cultivated-land expansion, the cultivated land area wil be 2.78×104 and 5.07×104 hm2 more than the threshold values of cultivated land at P=75 in 2020 and 2030 respectively. Even if the effi-cient water-saving technique are adopted, the water requirement of crop use wil in-crease from 19.77×108 to 20.82×108 and 21.95×108 m3 during 2010-2030, and then the ecological water use cannot be guaranteed. Conclusion] The cultivated-land ex-pansion would threaten the ecological security in Hotan River and Tarim River. Therefore, some strict measures should be taken to protect desert-oasis ecotone, an important constituent of oasis ecosystem which has vital role in maintaining the sta-bility of oasis, and to prohibit cultivated-land expansion.