玛纳斯河流域绿洲水文生态格局演变机理及适宜发展模式研究

Oasis is the carrier of human survival in arid area with unique characteristics of hydrology and ecological environment. The hydrological cycle process under the compound effect of artificial-natural process has significant influence on hydrological cycle process on oasis ecological evolution. How to research the oasis hydrological cycle impacted by natural and human and grasp the situation evolution of oasis ecological patterns is the key to determine moderate development scale of oasis and maintain the oasis security. The Manasi River basin oasis in north slope of Tianshan Mountain is selected as the study area, mainly research: ①Combined with the agriculture in oasis and water resources development and utilization characteristics, discriminate key process of water cycle and influential factor under compound effect of natural and artificial, simulate the exchange and transformation during various oasis water body, quantize water consumption process and reveal the oasis water consumption mechanism with the influence of artificial water taking-using-draining. ②To establish the responding relationship between groundwater depth variation and oasis hydro-ecological pattern evolution and build the dissipative distributed oasis hydro-ecological model. At the same time to simulate the hydro-ecological pattern respond of oasis with the compound effect, and reveal the evolution of oasis hydro-ecological patterns. ③To study the cumulative mutual effect between evolution of oasis hydrological condition and ecological pattern by natural and human impact. To study balanced relations and scale of oasis development in Manasi River basin, so as to put forward a development pattern to maintain oasis ecological security and adaptive regulation methods on water resources. The research provides a scientific basis for virtuous oasis circle in arid inland area.

绿洲是干旱区人类赖以生存的载体，具有独特的水文生态特征，人工-自然复合作用下的水循环对绿洲生态格局的演变起着决定性作用。因此从水文生态角度探索绿洲水循环过程，揭示绿洲生态格局演变机理，确立绿洲适宜发展规模是维持绿洲安全的关键。本项目选择天山北坡玛纳斯河流域绿洲研究：①结合绿洲农业与水资源开发利用特性，甄别人工和自然驱动力的水循环过程及关键影响因素，研究绿洲多种水体间的交换或转化机制，揭示人工取-用-排水干扰下的绿洲耗水机理。②研究地下水位变化与绿洲水文-生态格局变化响应关系，构建分布式散耗型绿洲水文-生态模型，模拟复合作用下的绿洲水文-生态格局变化响应，揭示绿洲水文生态格局演变机理。③研究绿洲水文条件及生态格局变化中的人工-自然驱动力对复合系统累积互制效应，确立玛纳斯河流域绿洲适宜性发展规模，提出维系绿洲生态安全的发展模式及水资源适应性调控策略，为干旱内陆区绿洲良性发展提供科学依据。

针对人工和自然复合作用下的绿洲水文循环发生改变，以干旱区绿洲-玛纳斯河流域为研究区，研究在时间和空间尺度上，绿洲荒漠化的水文-生态格局变化与适应性水资源利用关系。揭示人工取-用-排水干扰下绿洲耗水机理，建立基于水文生态格局变化的绿洲适宜性发展模式，以此提出适应性的水资源开发利用策略，确定大面积节水灌溉条件下人工绿洲的适宜规模，为干旱内陆区绿洲生态安全提供科学依据。主要成果如下：.1、分析绿洲水循环及人工取用排水干扰下的绿洲耗水机理。玛纳斯河流域不同下垫面的耗水强度为：耕地>林地>草地>灌木，耕地天然耗水量为3.49亿m3，占比逐年增大；根据主成分分析法，社会经济要素对绿洲耗水影响最大，其贡献率达到66.31%，而自然环境因子和上游来水因子的贡献率为33.69%。.2、揭示了地下水位变化与绿洲水文-生态格局响应关系。玛纳斯河流域平原区蒸散发呈现逐年递增趋势；地下水补给量约为蒸散发量的14.32%；现状节水灌溉种植比例下，流域蒸散发、地下水补给和地下水位降深分别为254.82 mm、38.22 mm和1.71m；节水灌溉种植增加比例为20%，分别减少到184.71 mm、27.71 mm和2.84m；减少20%时，分别增加到324.92 mm、48.74 mm和0.42m；在地下水位埋深小于5.5m处，增加冬灌一次灌水量为1400 m3/hm2；在地下水位埋深位于5.5-9.0m内，增加冬灌一次灌水量为1250 m3/hm2。.3、阐明了绿洲适宜性发展规模及水资源适应性调控策略。研究发现，实施节水灌溉后，流域耕地规模年均增长81.9km2，增长速度是实施节水灌溉前的4.36倍；膜下滴灌技术使绿洲适宜规模提升17.6%；在2021~2030年间，玛纳斯河绿洲规模应控制在7756km2~11635km2；2031~2040年间，规模应控制在7823km2~11735km2；2041~2050年间，规模应控制在7465km2~11198km2。.玛纳斯河流域水资源量的变化深刻影响着绿洲的稳定性，构建符合流域水文变化特征的模型，对充分认识未来流域水资源变化规律和定量分析绿洲适宜规模均具有重要意义，研究节水灌溉条件下玛纳斯河流域水循环演变规律和响应机理，有利于系统阐述节水灌溉过程中的各项理论和实际问题，可以为制定绿洲可持续发展策略提供参考。