黄土高原地区退耕还林还草对陆地水储量的影响及其机理的集合模拟研究

The Grain for Green Project has dramatically been changing the landscape and the regional terrestrial water cycle in the Loess Plateau. Showing by both satellite- and ground- based observations, the regional terrestrial water storage has constantly been decreasing during recent years, which draw a threat to the accomplishments of the project and future developments of the local ecosystem, economy, and the society. Here, we propose a study of the revegetation effects on regional terrestrial water storage in the Loess Plateau using multi-forcing-multi-parameterization Noah-MP ensemble simulations. The critical atmospheric forcing variable and physical processes affecting the terrestrial water storage in the Loess Plateau will be addressed by inter-comparing the ensemble members, potentially leading to better understanding of the hydrological processes and more precise simulations. The effects of the revegetation on regional terrestrial water storage will be studied through the comparison of two ensemble simulations using current and pre-revegetation land cover. In addition, by differing the afforesting and grass-growing effects on simulated terrestrial water storage changes, a more appropriate revegetation strategy would be suggested for the Grain for Green Project under the semi-arid climatic conditions in the Loess Plateau.

黄土高原地区退耕还林还草工程极大地改变了区域内植被覆盖状况和陆地水循环特征。近年来，卫星和地面观测资料表明，黄土高原地区陆地水资源储存量持续下降，这威胁到了退耕还林还草工程的可持续性，以及工程已取得的生态、经济、社会成果。本项目拟利用Noah-MP陆面过程模式，使用多大气驱动场、多物理过程参数化方案集合模拟技术，开展退耕还林还草前后植被变化对区域陆地水储量影响的敏感性实验。通过数值模拟，定量评估黄土高原半干旱气候条件下、影响陆地水储量及其各分量模拟的关键大气驱动变量和物理过程参数化方案，降低该地区陆地水储量模拟的不确定性；在此基础上，分析人工植被对蒸散发、干旱度的影响，研究植被对陆地水储量变化的影响机理；进而对比“还林”、“还草”区域陆地水储量变化的不同，探讨适合于该地区的“退耕”方式，为退耕还林还草工程的可持续建设提供科学依据。

项目使用NoahMP陆面模式多参数化方案组合、普林斯顿大学全球0.25°和中科院青藏所中国区域0.1°地面气象要素数据集、FAO和北京师范大学土壤质地数据集，开展了2001-2012年中国区域多驱动、多参数化方案、多参数集合模拟。系统评估了NoahMP陆面模式对中国区域陆地水储量的模拟能力。耦合了NoahMP陆面模式和RAPID河网汇流模式，探讨了使用河流流量观测数据评估陆面过程模拟的方法。发展了一个新的参数化方案敏感性量化方法，定量评估了湍流、叶孔阻抗、产流多个过程参数化方案对模拟不确定性的贡献。以上研究为改进模式、提高中国区域水文过程和陆地水储量模拟能力提供了参考。