青藏高原内流区典型湖泊蒸发随湖泊深度变化研究

Studies have shown that endorheic lakes in the inner Tibetan Plateau are experiencing significantly expansion with an notable increase of lake area and a rapid rise of lake level，leading to obvious change of lake depth during the past 30 years. As the unique water expenditure from the endorheic lakes，the precise quantification of lake evaporation is the key factor to reveal the reason of lake expanded. Earlier researches proved that lake evaporation process was different from the land surface. The seasonal variation of lake evaporation and solar radiation illustrated different steps, with most of the solar radiation was stored in the lake rather than high turbulent exchange of sensible heat flux and latent heat flux. Due to the heat storage change is mainly determined by the lake depth, it is essential to clarify the effect of depth on lake evaporation in order to understand the mechanism of lake change in the Tibetan Plateau. In this study, the largest deep lake, Lake Siling Co in the inner Tibetan Plateau will be chosen to precisely quantify the lake water/heat exchange on point scale and improve the parameters in the lake energy balance model on the basis of previous lake water/heat observation platform. Evaporation from the whole Lake Siling Co will be calculated by using the grid China Meteorological Forcing Dataset and the simulated results will be validated by the observation of lake water temperature profile in different depth then the effect of lake depth change on lake evaporation will be investigated ultimately. At last, according to the existing depth, area, and water level data from the inner Tibetan Plateau, the amount of evaporation from different lakes with different area and depth will be quantified in the past 30 years. This work will help to understand the hydrological processes mechanism of lake expansion - lake depth change - lake evaporation change and provide the basis for the study on the lake expansion reason in the inner Tibetan Plateau.

近30年来青藏高原内流湖伴随面积显著扩张，水位亦明显上涨，导致其深度变化显著。作为内流湖的唯一水分支出项，湖泊蒸发的精确量化是揭示湖泊扩张原因的关键。前期研究显示湖面蒸发过程与陆面差异极大，湖面蒸发与辐射交换呈现不同步季节变化，夏季大量辐射能转化为热储量，而不是升高湍流交换。由于储热变化与湖泊深度密切相关，厘清湖泊深度变化对湖面蒸发的影响对认识高原湖泊变化机理至关重要。本项目拟以青藏高原内流区色林错已有的湖泊水热观测平台为基础，精确量化点尺度湖泊水热交换，改进湖泊能量平衡模型中参数化方案；利用格点气象驱动数据，以多点水温廓线观测为验证，完成整个湖面蒸发模拟计算，研究单一湖泊扩张伴随的深度变化对湖面蒸发的影响；结合高原内流区已有的湖泊深度、面积和水位变化观测资料，量化不同深度的湖泊近30年来蒸发量的变化，阐明湖泊扩张-深度变化-湖面蒸发的水文过程响应机理，为青藏高原湖泊扩张机理研究提供依据。

近40年来青藏高原内流湖伴随面积显著扩张，水位亦明显上涨，导致其深度变化显著。作为内流湖的唯一水分支出项，湖泊蒸发的精确量化是揭示湖泊扩张原因的关键。前期研究显示湖面蒸发与辐射交换呈现不同步季节变化，夏季大量辐射能转化为热储量，而不是升高湍流交换。由于储热变化与湖泊深度密切相关，厘清湖泊深度变化对湖面蒸发的影响对认识高原湖泊变化机理至关重要。本项目以青藏高原内流区色林错已有的湖泊水热观测平台为基础，增设了色林错湖温廓线观测，同时开展了然乌湖水热通量和湖温廓线观测，精确量化了典型湖泊点尺度湖泊水热交换特征；评估了不同类型湖面蒸发模型在青藏高原典型湖泊蒸发模拟中的适用性；通过一维能量平衡模型敏感性分析，揭示了典型湖泊深度变化对湖面蒸发的影响；利用湖泊储热滞后模型，量化了青藏高原面积大于10km2的400多个湖泊蒸发量，阐明了典型湖泊扩张-深度变化-湖面蒸发的水文过程响应机理，探讨了湖泊蒸发变化对典型湖泊快速扩张的影响，为青藏高原湖泊扩张机理研究提供了科学支撑。