黄土丘陵沟壑区植被-水文过程的尺度效应研究

Vegetation change is an important influence factor of the hydrological process. Since 2000, the runoff had reduced dramatically in the middle reaches of Yellow River, and the type and structure of vegetation in the Loess Plateau had changed significantly. However, it is obviously insufficient for the effect mechanism of the vegetation on the hydrological process in the new normal vegetation. It is lack of relationship among vegetation and hydrological process in different spatial scale, especially. The regional focus of this study is the hilly-gullied loess region. Remote sensing and ground monitoring data were used to observe and analyze the hydrological process characteristics in slope-catchment-watershed scale and vegetation pattern in the pixel-landscape-regional scale. The relationship of vegetation pattern and hydrological process in the different scales was analyzed. The key influencing factors were identified and extracted, and the characteristics and thresholds of the key factors were evaluated quantitatively. The hydrological model based multi-scale remote sensing was established. The spatial scale features and scale of vegetation-hydrological processes were studied under the new normal conditions in the hilly-gullied loess region. It will be strengthening the achievement of eco- hydrological scale effect in the Loess Plateau. This research has great potential of innovation in the researches of vegetation - hydrological process comprehensive observation and the thresholds of influencing factors for the vegetation - hydrological process and transformation law. Besides, scientific evidence would be provided from this research for the scale effect and scale conversion method based on remote sensing hydrological model. This will facilitate the advance in water resources management and soil and water conservation research.

植被变化是影响流域水文过程的重要因素。2000年以来黄河中游径流锐减，黄土高原植被类型和结构发生明显变化，然而新常态下植被对水文过程的影响机理研究明显不足，尤其是缺乏植被-水文过程尺度效应研究。本项目拟选择黄土丘陵沟壑区为研究对象，耦合遥感与地面监测数据，观测和分析坡面-集水区-流域尺度水文过程特征和像元-景观-区域尺度植被格局特征；分析不同尺度上植被格局与水文过程关系，识别并提取关键影响因子，定量评价关键因子的尺度特征及阈值；建立多尺度遥感水文模型，综合研究黄土丘陵沟壑区新常态下植被-水文过程的空间尺度特征及尺度效应，深化黄土高原生态-水文尺度效应研究。项目将在多尺度天-地一体化植被-水文过程观测、不同尺度下植被-水文过程影响因子的尺度阈值及转换规律等方面进行创新，发展遥感水文模型支撑下的尺度效应分析和尺度转换方法，为流域水资源管理和水土保持研究提供科学依据。

植被变化是影响流域水文过程的重要因素，2000年以来黄河中游径流锐减，黄土高原植被类型和结构发生明显变化，然而新常态下植被对水文过程的影响机理研究明显不足，尤其是缺乏植被-水文过程的尺度效应研究。本研究选择黄土丘陵沟壑区集水区-小流域-流域3种不同空间尺度流域为研究对象，耦合遥感与地面监测数据，分析了不同空间尺度的水文过程特征和植被格局；研究了不同尺度下植被格局与水文过程关系；建立了多尺度水文模型，综合分析了黄土丘陵沟壑区植被-水文过程的空间尺度效应。项目获取了多尺度植被-水文过程观测数据，采用变异系数法、Moran′s I指数法和信息熵法，分析了集水区-小流域-流域尺度植被NDVI空间异质性。结果表明3种分析方法结果基本一致，均能较好体现植被空间异质性，总体规律为集水区和小流域尺度下植被空间异质性较强，流域尺度下植被分布空间异质性较弱。研究区内不同集水面积的年径流变化过程呈正相关性，径流空间相关性受空间地理位置、流域面积的影响，空间尺度变化对不同季节水文过程影响存在较强异质性。分析了集水区-小流域-流域3种空间尺度下植被对蒸散发、径流系数的影响机制，结果表明蒸散发量与植被NDVI均呈正相关性，且随着空间尺度的增加，蒸散发量与植被NDVI的相关性逐渐增大。径流系数随植被NDVI的增加呈减小趋势。集水区-小流域尺度下植被NDVI与径流系数的相关性高于流域尺度下植被NDVI与径流系数的相关性。利用多尺度水文模型，分析了不同空间尺度下植被-水文过程的影响关系，分析研究区不同尺度汇流面积下植被-水文过程模拟精度，在此基础上从气候变化、退耕还林等方面，多情景模拟分析植被变化对不同尺度径流变化的影响。深化黄土高原生态-水文尺度效应研究，为流域水资源管理和水土保持研究提供科学依据。