干旱区内陆河尾闾湖泊湿地生态需水及保护研究- - 以玛纳斯湖湿地为例

The ecological conservation goals of lake wetlands of inland river basin in arid area are not clear, and some conventional methods for calculating ecological water requirement are restricted to a certain degree in the arid area, thus it is much arbitrary to determine the quantity of water replenished to lake wetlands, which causes great impact on the water resources planning and rational allocation for the ecology of river basin in arid areas. In this study, based on the unique characteristics and ecosystem structure of lake wetlands of inland river basin in arid area, to safeguard the stability and sustainability of the ecosystem of lake wetlands, according to the eco-hydrological conditions of indicators needed for survive and growth, taking Manas Lake wetland as the study object, it profoundly reveals the eco-hydrological interaction mechanism of the indicators in lake wetlands firstly, through the comprehensive technological methods of on-the-spot investigation, laboratory experiments, and so on. Then in view of the relationships among the indicators, water level, the salinity of the water body and the water quantity of the lake in arid areas, it builds an eco-hydrological model of lake wetlands in inland river basin. Subsequently, using the model and taking the water level and salinity as the constraints of ecological and hydrological factors, it quantitatively analyses the ecological protected goals, and calculates the ecological water requirement under the corresponding goals of Manas lake wetland. Finally, combining the analysis of water resources development and utilization in the middle and lower reaches of the Manas River, it gains the quantity of available water for the wetland and control measures of the water resources. This research will enrich the methods for calculating ecological water requirement of lake wetlands, providing the theoretical foundation and technical support of ecological protection goals determination of lake wetlands for that in the similar regions, and it may also directly serves the implementation of ecological water replenishment measures, therefore, it has more important theoretical and practical significance to the water resources planning and allocation of watersheds.

干旱区内陆河尾闾湖泊湿地生态保护目标不明确，现有生态需水计算方法受限，生态补水随意性较大，给干旱区面向生态的流域水资源规划及合理配置带来较大影响。本研究拟从干旱内陆河尾闾湖泊湿地特性及其生态系统结构出发，以玛纳斯湖湿地为研究对象，根据指示物种生存生长所需生态水文条件，通过实地考察和室内试验等手段，揭示湿地指示物种生态-水文相互作用机理；基于干旱区独特的"指示物种-湖泊水位-矿化度-水量"关系，构建干旱区湖泊湿地生态水文概念模型；利用模型及指示物种生态水文要素约束条件，定量分析玛纳斯湖湿地的生态保护目标及相应目标下的生态需水量；结合流域中下游水资源开发利用状况，分析湿地可用生态水量及调控措施。本研究丰富了湖泊湿地生态需水计算方法，研究成果可为类似区域湖泊湿地生态保护目标的确定提供理论基础和技术支撑，指导湿地生态补水措施的实施，对流域水资源规划及配置具有比较重要的理论和实践意义。

在近几十年干旱区内陆河流域水、土资源大规模开发利用过程中，流域尾闾湖泊湿地因入湖水量减少而严重萎缩甚至消失。随着流域内一系列生态环境问题的突显，尾闾湖泊湿地的保护或恢复日益得到重视，而其保护目标及相应的生态需水量确定是亟需解决的关键问题之一。本研究提出了基于湖泊湿地生态水文模型的湿地生态需水计算理论方法，并以玛纳斯河流域尾闾湖泊为例，定量计算了其不同恢复目标下的生态需水量。取得的主要成果有：（1）分析了湖泊湿地的水文要素与湿地指示物种的相互作用机理。湖泊湿地的降水、蒸发、入湖流量等水文变化过程决定着湿地的水位、面积、蓄水量等要素，这些要素通过水深、浅滩面积、水体矿化度等影响着湿地动物栖息地选择、食物的分布和多寡，以及植物气孔开合、细胞分裂等生命活动。（2）确定了指示物种和关键物种及其对湿地关键影响因素的响应阈值。通过实地调查和文献调研，确定了玛纳斯湖湿地的指示物种为水鸟和芦苇，关键物种为底栖动物。影响底栖动物生存的关键因素为湖水矿化度，其阈值为20g/L；影响芦苇生长的关键因素是水深和水体矿化度，水深阈值为-30～50cm，矿化度阈值为80g/L。（3）基于“湖泊面积-水量-矿化度关系”建立了玛纳斯湖湿地的生态水文模型。利用44幅遥感影像提取了各个时期玛纳斯湖湿地的水面面积；提出了基于TIN提取湖泊湿地形态曲线的方法，获得了不同高程下玛纳斯湖的面积和蓄水量；通过分析玛纳斯湖盐矿储量得到了湖水矿化度和蓄水量之间的关系，从而建立了玛纳斯湖湿地生态水文模型。（4）计算了玛纳斯湖湿地恢复目标和不同恢复目标下的生态需水和补水量，并从流域本身和外流域调水两方面分析可采取的水资源利用和调控措施。利用SWAT模型和卡拉玛依市的逐年降水，模拟和估算了流域可用水量，1981～2007年流域年均可用生态水量在2亿m³左右；湿地最低恢复目标为：保持水面面积100km²，需要补水3.8亿m³；合理目标为保持面积200～300km²，矿化度87.4～152.4g/L，需要补水12.15～22.19亿m³。本研究为干旱内陆河流域尾闾湖泊湿地生态需水计算提供了一种新思路，为玛纳斯湖湿地恢复目标和生态补水量的确定提供了参考依据，为未来玛纳斯河流域用水结构转变下的水资源合理配置提供了理论和技术支撑。