遥感与模型耦合的阿牙克库木湖水量平衡定量研究

The harsh natural environment makes it little knowledge about the inland lakes and mountains glaciers in the northern Tibetan Plateau, and the scarcity of in situ data leads to there is no quantitative study on lake water balance in the depopulated zone of northern Tibet. In this study, we first employ available multi-source remote sensing data to estimate the change trends of water volume and replenishment glacier reserves in Ayakekumu Lake from 1964 to 2020, including the decryption of satellite photographs, optical remote sensing images and radar altimetry data. In particular, we explore key methods such as the method for combining 4 types of radar altimetry to reveal the changes trends of water level in long time series, and the method for reconstructing digital elevation model of glacier surface using stereo pair images of declassified satellite photograph. In addition, the WEB-DHM model and Penman-Monteith model are used to estimate precipitation-generated runoff and lake evaporative flux, respectively. Finally, we quantitatively assess the climate response mechanism of lake water balance by inputting 6 parameters into water balance equation, e.g. lake water volume changes, glacier melt water-generated runoff, precipitation-generated runoff, lake evaporative flux, lake precipitation amount and errors, so as to supplement the existing studies of ecological changes and water resources balance in the depopulated zone of northern Tibet.

自然环境的恶劣使得人们对青藏高原北部地区的内陆湖泊和山地冰川知之甚少，实测数据的缺失导致藏北无人区湖泊水量平衡的定量研究几乎是空白。该项目融合可获取的多源遥感数据（解密卫片、光学遥感影像、雷达测高数据）估算出1964-2020年阿牙克库木湖水量和补给冰川储量的变化趋势，并探索联合多种类型雷达测高数据进行长时间序列水位监测、基于解密卫片立体相对生成冰川表面DEM等关键技术。此外，本项目还利用WEB-DHM模型和Penman-Monteith模型分别估算出降水形成的入湖径流量和湖面蒸发量。最后将湖泊水量变化、冰川融水产生的径流量、降水形成的入湖径流量、湖面蒸发量、湖面降水量以及误差等因子输入湖泊水量平衡方程式来定量化评估阿牙克库木湖水量平衡的气候响应机制，补充严重稀缺的藏北无人区生态变化及水资源平衡研究。

较少的人类活动使得青藏高原的高山湖泊成为亚洲甚至是全球气候变化的指示器，但恶劣的自然环境却导致了人们对青藏高原的高山湖泊和山地冰川知之甚少。当前，基于遥感技术进行的湖泊水量变化估算及分析冰川融化、气候变暖、降水增加对湖泊的影响机制成为青藏高原水资源平衡及气候演变等研究的热点。本课题开展了为期三年的研究，采用卫星测高等多源遥感数据估算出阿牙克库木湖等青藏高原典型湖泊及其补给冰川的物质平衡，并探索了湖泊水量变化的气候驱动机制。课题主要的研究内容和成果概况如下：①青藏高原中部、北部地区绝大部分湖泊水位持续增加，但南部地区的部分湖泊却出现水位下降的现象；②青藏高原大部分山地冰川呈现持续退缩的趋势，但部分区域的气候暖湿化却导致了某些冰川出现物质正平衡的现象；③青藏高原湖泊水量变化的主导机制是降水量增加，冰川融水是湖泊水量变化的重要影响因素。气候暖湿化背景下的降水、气温、蒸发、日照、风速变化等深刻地影响着青藏高原湖泊与冰川的物质平衡。本课题的研究成果和结论有助于进一步深入理解青藏高原地区湖泊变化的历史过程以及与气候变化之间的关联，并预测其变化趋势和最终命运。