基于源汇景观格局流域水土流失评价与优化调控

Soil erosion is an ecological process reflects the degradation of the surface environment, and closely related to the watershed landscape pattern. Discussion about influence of watershed landscape pattern on soil erosion process and its source-sink regulating mechanism is of great significance to further recognizing the relationship between landscape pattern and soil erosion process and strengthening watershed comprehensive treatment and planning. In this project, the Yanhe watershed in the middle reaches of the Yellow River area is chosen as the research objective. The long time sequence hydrological monitoring records and meteorological data are collected to support the project, the remote sensing (RS)、geographic Information system(GIS) 、137Cs tracing technique、RUSEL, and landscape resistance model will be used in this study. The landscape spatial pattern indexes、source-sink landscape theory、geostatistical method and Principles of hydrology are synthetically applied. By carrying out some analysis and evaluation work such as regional soil erosion dynamic evaluation, regional differences in sediment transport properties and landscape spatial pattern multi-angle quantization, the project will reveal the characteristics of terrain differentiation and spatial variation law of soil erosion under the influence of land-use and vegetation cover change, the key pattern factors affecting the soil erosion process will be identified, and the technology and scheme of source-sink landscape optimization will be put forward to enhance soil and water conservation based on the quantitative expression of spatial distribution and function of source-sink landscape and its equilibration of source-sink configuration. The results will provide scientific evidence for vegetation restoration construction in hilly and gully area, benefiting to the planning and management of soil and water conservation in the middle reaches of the Yellow River.

水土流失作为一种表征地表环境退化的生态过程，与景观格局关系密切。基于“源汇”景观格局分析，开展水土流失评价研究，对深化景观格局与水土流失过程耦合关系认识，提高水土流失治理水平及科学性，具有十分重要的意义。本项目以黄河中游区延河流域为对象，收集长期水文监测记录和景观要素资料，借助遥感、GIS、137Cs示踪等技术和RUSLE、景观阻力面等模型，综合运用景观生态学、地统计学、流域水文学方法和原理，通过景观格局多角度量化、流域水沙运移和泥沙输移特性分析评价，揭示流域地形分异、土地利用及植被覆盖变化下水土流失空间变异规律，辨识影响水土流失过程的关键因子，阐明水土流失过程与景观及其“源汇”格局相互关系，量化表达“源汇”景观空间分布、功能强度及配置均衡性，进一步提出增强水土保持功能的“源汇”景观最优化配置技术与方案。研究结果期冀为黄河中游丘陵沟壑区植被恢复建设、水土保持规划与管理提供重要的科学依据。

水土流失作为一种表征地表环境退化的生态过程，与流域景观格局关系密切。本项目以黄河中游区延河流域为对象，收集长期水文监测记录和景观要素资料，借助遥感、GIS、137Cs示踪等技术和RUSLE、景观阻力面等模型，综合运用景观生态学、地统计学、流域水文学方法和原理，开展“源汇”景观格局分析与水土流失评价研究，多角度探讨景观格局与水土流失过程耦合作用关系与调控机制。主要研究结果：（1）延河甘谷驿流域径流、输沙量呈现较为明显的下降趋势，潜在蒸散量表现为显著上升趋势，而降水量则表现为不显著上升趋势。与1980s相比，径流深和多年平均输沙量在本世纪10年代的平均降幅分别达到30.5%和86.55%，流域尺度径流量和输沙量时间序列发生突变的年份分别为1999年和2007年；（2）退耕还林使得研究区的景观格局发生了剧烈变化，源景观表现出较为明显的“小斑块、破碎化”趋势，空间异质性增强，汇景观则主要向大斑块方向发展；（3）景观格局调整引起的植被条件变化对水沙过程的影响程度最大，对径流量和输沙模数下降的贡献率分别为88.70%和90.08%，植被恢复措施对径流减少的影响在一定阈值内是有效的；（4）影响延河流域径流和泥沙过程的主导因子为源汇景观格局和降水量两个因子的单因子作用，归因分析表明，下垫面条件改善是径流减少的主导因素，贡献率达96.78%；（4）耕地的边缘密度、林地的散布和并列指数、草地的散布和并列指数对于水沙过程的变化存在显著统计学差异且贡献程度较高，在今后的生态恢复中，应重视造林规模及其可能产生的负生态水文效应；（5）结合已取得的数据和研究结果，探索形成3种流域水土流失评价途径，分别是：基于土地利用“源汇”景观质量分配合理性评价框架、基于RUSLE土壤侵蚀动态-景观生态安全格局评价框架、像元水平泥沙输移比-景观阻力耦合评价方法。研究结果可为丘陵沟壑区植被恢复、流域水土保持规划、山水林田湖草沙一体化修复提供有价值的指导。