| 摘要: |
| 柴达木盆地盐湖对维系区域生态平衡、保障农业安全和国民经济发展具有重要的作用。受青藏高原气候暖湿化影响，盆地湖泊格局发生了一系列变化。为分析盆地盐湖变化特征，本文以小柴旦湖为例，基于长时间序列卫星数据，利用随机森林法提取盐湖水域范围并解构、评估“点—线—面”形态变化，同时构建矿化度指数表征盐湖资源禀赋。结果表明：（1）1990—2022年小柴旦湖面积呈“缓减—缓增—快增”的阶段性变化特征，岸线长度呈阶段性变化（2016年后增长明显），湖泊质心总体向西北方向迁移，截止2022年湖泊质心累计迁移距离为2363.49 m。（2）1990—2022年矿化度指数波动下降，呈“淡化”态势。（3）气象数据显示研究区年平均气温升高、年降水量增多、年潜在蒸散量下降，处于暖湿化轻度转型期，降水增多、蒸发下降、增温引起的冰雪融水增加综合叠加效应引起区域水资源增加，进而导致湖泊扩张和“淡化”。（4）小柴旦湖扩张和“淡化”对社会经济和生态平衡影响明显，一方面，影响湖区周边基础设施，近70 km2区域受淹没直接影响，包括德小高速公路、柳格高速公路部分路段；另一方面，作为资源型湖泊，小柴旦湖盐湖矿产资源开发利用潜力下降，“淡化”或将引起湖泊生态系统失衡。（5）未来应适当调整小柴旦湖开发利用方向，挖掘“雪山—荒漠—盐湖—湿地—公路”视觉多元化立体景观资源，平衡盐湖“资源”与“生态”属性。本研究从湖泊动态变化研究的视角，结合多种方法开展了有益的尝试，分析结果可为柴达木盆地盐湖资源和生态环境保护及基础设施建设提供决策支撑。 |
| 关键词: 盐湖 卫星遥感 随机森林 质心 矿化度 |
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| Expansion and influence analysis of the Xiao Qaidam Lake in Qaidam Basin since 1990 |
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zhucunxiong,FAN qishun,YAN yingcun,XIAO ruixiang
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Qinghai Provincial Key Laboratory of Geology and Environment of Salt Lakes
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| Abstract: |
| Salt lakes in Qaidam Basin plays an important role in maintaining regional ecological balance and ensuring national economic development. Under the influence of climate warming and humid on the Qinghai-Tibet Plateau, a series of changes had taken place in the lake pattern in the basin. In order to analyze the change characteristics of salt lake resources in the basin, the Xiao Qaidam Lake (XQL) was taken as the research object, based on the long time series satellite data, the random forest method was used to extract the range of salt lake and analyze its point-line-surface changes. At the same time, the salinity index was constructed to represent the change of salt lake resource endowment. The results showed that: (1) the area of XQL showed a gradual change characteristic of "slow decrease, slow increase and fast increase" during 1990-2022. The length of shoreline basically increased with the area increasing, and showed a phased change. This trending is obvious after 2016. The cumulative migration distance of the lake"s centroid was 2363.4 m until 2022, and the overall migration direction was in northwest. (2) The fluctuation of salinity index decreased from 1990 to 2022, indicating a trend of "dilution". (3) Meteorological data showed that the study area was in a mild transition period of warm and humid, and the comprehensive superposition effect of increasing precipitation, decreasing evaporation and increasing ice. The snow meltwater caused by increasing temperature leaded to the increase of regional water resources, which resulted into lake expansion and "desalination". (4) The expansion and "dilution" of XQL had a significant impact on the social economy and ecological balance. On the one hand, it affected the surrounding infrastructure, and nearly 70 km2 area was directly submerged by rapid increasing lake area, including some sections of G315 and G3011 Expressway; On the other hand, as a resource-based lake, the potential of mineral resources XQL had declined, and "desalination" might cause the imbalance of lake ecosystem. (5) It suggested that it should appropriately adjust the development and utilization direction of XQL in the future, excavate the visual diversified three-dimensional landscape resources of "snow mountain-desert-salt lake-wetland - highway", and balance the "resource" and "ecological" attributes of the salt lake. This study provides a useful attempt to enrich the perspectives and methods of lake dynamic change research, and the analysis results can provide certain decision-making support for the resource, ecological environment protection, and infrastructure construction of the salt lake in Qaidam Basin. |
| Key words: salt lake satellite remote sensing Random Forest center of mass salinity |
