青藏高原北麓河盆地多年冻土退化对地下水渗流过程的影响研究

Degradation of permafrost due to climate warming and engineering construction is expected to have a profound impact on regional hydrological regime shifts, which may cause eco-hydrological problems and contribute to instability of critical infrastructure. However, gaining predictive capability of the consequences of hydrological regime changes is a persistent challenge due to a dearth of supporting groundwater flow researches on the interior Qinghai-Tibet Plateau (QTP). This project aims to understand the hydrologic impacts of permafrost degradation on groundwater flow patterns and thermal regime at a local scale. Beiluhe basin, with representive permafrost environment on the QTP will be selected as the study area. Through ground geophysical methods including nuclear magnetic resonance, the permafrost degradation characteristics and groundwater conditions will be accurately obtained at local scale. We will apply the stable isotopic method and field thermal borehole observations to elucidate the hydrological regime shifts and the groundwater thermal regime among different water components. Based on these field obseavation data, using a two-dimension numerical model, we aim to explore and evaluate the long-term hydrogeological regime changes under the conditions of permafrost degrading. The results of this project will be much helpful to comprehensively understand the hydrologic impacts of climate warming in permafrost region, and provide important original data and technical supports for studying the hydrological processes and infrastructure planning on the QTP.

气候变暖及工程活动加剧了青藏高原多年冻土退化过程，这必然导致区域性水文环境的改变，引起一系列生态与水文环境问题甚至工程病害。因缺乏对局地尺度上冻土退化对地下水渗流过程的影响及其演变规律的充分认识，使得冻土区生态环境评估与预测存在明显不足。本项目拟针对局地尺度下多年冻土退化影响浅层地下水渗流的路径与方式这一科学问题，选取局地因素典型的北麓河盆地为研究区域，通过核磁共振等物探方法查明冻土退化特征以及地下水分布特征；应用同位素示踪技术，结合钻孔观测分析阐明不同水体间的水力联系以及水热关系；利用上述观测结果，借助已有的二维冻土水文模型，进一步理解和评估多年冻土退化对地下水渗流过程的影响机制和长期变化趋势。研究成果将有助于更加全面的认识气候变暖对局地尺度上寒区水文环境的影响，为下一步深入研究青藏高原水文过程以及工程建设提供科学数据和技术支持。

气候变暖和人类活动加剧了青藏高原多年冻土退化过程，这不仅导致区域性水文环境的改变，加剧冻土中的碳释放，同时也引起一系列生态与水文环境问题甚至工程病害。因缺乏对局地尺度上冻土退化对地下水渗流以及地貌变化过程的影响及其演变规律的充分认识，使得冻土区生态环境评估与预测存在明显不足。本项目针对局地尺度下多年冻土退化影响浅层地下水渗流的路径与方式这一科学问题，选取局地因素典型的北麓河盆地为研究区域，通过地质雷达等物探方法查明冻土退化特征以及地下水分布特征；应用地温钻孔和土壤水分观测分析阐明不同地貌单元下水热特征及差异；利用上述观测结果，借助已有的冻土-水文-地貌变化模型，进一步理解和评估多年冻土退化对地下水渗流过程的影响机制和长期变化趋势，研究了富冰冻土区地貌对气候变化的响应过程。结果表明，不同地貌单元浅层水热状态差异较大；富冰冻土区热喀斯特湖热源效应较为明显，在气候变暖背景下，热喀斯特湖热源效应加剧；同时，由于侧向水流的热影响，未来多年冻土退化程度明显高于没有地下水渗流的区域。研究成果将有助于更加全面的认识气候变暖对局地尺度上寒区水文环境的影响，为下一步深入研究青藏高原水文过程以及工程建设提供科学数据和技术支持。