气候变化下长江江源区水文环境和径流时空演变与预测研究

In recent 60 years, under climate change of the whole world, it had produced a great impact that the hydrological element (precipitation / temperature / evporation) and hydrological environment (glacier / frozen soil / sonw retention / swamp / moss land) in the source region of the Yangtz river, China. This research focuses on the spatial-temporal variation of the hydrological elements and the hydrological environments, using mutivariate statistical regression analysis, for understatied the contribution to river runoff during ablation about glacier or frozen soil or sonw retention, and degeneration about swamp and moss land, and find out the hydrological process and mechanism. Through work out the precipitation-runoff-temperature distribution hydrologic model, then reveal the secrets of the change of hydrological cycle and the process of runoff producing precipitation and rivers confluence, becase a variation of the hydrological elements and the hydrological environments. Therfore, it was determined that change characteristics and tendency of hydrological elements. Acroding to different climate scenes, probe into the spatial-temporal variation objective law and space pattern, predicte the changes of the hydrological elements and the hydrological environments at the same time. Finally, study scientofic basis and certain specific policies for the stabilize Tibet politics, dispatching south-to-north waterdiversion, regulating water resources of Three canyon dam and reservoir.

长江江源高寒地区近60年以来，在全球气候变化条件下，对水文气象要素（降水/气温/蒸发）和水文环境（冰川/冻土/积雪/湿地/沼泽）已发生重大影响。本项目采用多元统计分析理论和方法，对水文气象要素和水文环境的时空变化特征及其影响程度进行研究，弄清冰川/冻土/积雪消融退化和湿地/沼泽减少对河川径流补给的贡献，查明径流形成过程和径流形成机制；通过构建具有流域尺度效应的降水~径流~气温耦合分布式水文模型，揭示水文气象要素改变和水文环境变迁如何共同作用来驱动研究区水文循环与其对产汇流过程的影响，并确定水文要素多时间尺度变化特征与变化趋势；在假定不同的气候组合情景或超长期的气候模拟情景下，探索径流时空演化规律和未来可能变化趋势及其时空格局与模式，并进行各水文气象要素和水文环境的预测。进而为维护藏区稳定、南水北调跨区水资源调配、长江流域水资源和干流水库群乃至三峡水利枢纽安全调度运行提供科学依据和决策支持。

在全球气候变化背景下，长江江源高寒地区的水文气象要素（气温/降水/蒸发/径流）和水文环境（冰川/冻土/积雪/湿地/沼泽/植被）已发生重大影响，尤其是随着气候变暖导致长江江源地区出现了冻土及冻土环境退化、植被退化、冻融侵蚀和土地荒漠化的四大生态环境问题。本项目通过对该地区近50a气候变化对水文气象要素和水文环境影响的辨析，并结合国家需求和科学问题两个层面的思考与认识，取得如下研究成果：1）基本弄清长江江源高寒地区蒸发力水平分布规律、随海拔高度变化规律、年内及年际演变规律及其成因，蒸发量的空间分布及其年内和年际变化统计特征，从而揭示水汽输送通道和降水时空分布规律；2）初步查明长江江源高寒地区在长系列气候变化下的水文环境要素变迁及其径流形成过程和径流形成机制；3）揭示了长江江源高寒地区冰川、冻土、积雪、湿地和沼泽等变化下的产汇流变化特征与径流变化过程和水文循环；4）同时，提出基本水文要素时空格局与模式，预测了长江江源高寒地区未来气候变化情景下径流的可能变化趋势。上述研究成果，将为长江江源高寒地区水资源定量估算和评价提供科学的理论依据，对保护川西北高寒草原并创造良好的生态环境提供科学的决策依据，以及对于促进长江、黄河上游地区和岷江、大渡河、嘉陵江的河源区生态屏障建设，特别是保障三峡库区水资源安全利用研究能够起到一定的参考作用。