西南喀斯特地区地表地下二元结构发育，降水几乎全部下渗，壤中流作为下渗水的一个重要去向，其发生条件和主要驱动机制尚不清楚，这阻碍了对喀斯特地区水文循环的深入认识，限制了有限水资源的合理利用。项目以喀斯特地区灌木丛、草地、坡耕地等3种典型土地利用方式坡面作为研究对象，运用传统水文监测的方法，结合模拟降雨试验，通过监测不同坡位（上、中、下）土壤水文过程，研究植物-土壤-岩石耦合构造、外部环境因子、深层渗漏等对壤中流过程的影响，明确壤中流的主要影响因素和发生条件；同时，在试验过程中结合探地雷达和稳定性氢氧同位素示踪的方法，探讨壤中流运移路径和新旧水组成，深化对壤中流产流机制的认识。通过以上研究阐明西南喀斯特地区坡面壤中流过程及其驱动机制，为该地区土地利用合理布局和石漠化综合治理提供科学依据。

Karst region of southwestern China is characterized by its thin soil cover as well as dual structure of hydrological processes, consequently almost all rainfall water infiltrates into the soil as subsurface flow and deep percolation. Although subsurface flow has been recognized as an important component of infiltration water, its generation conditions and driving mechanism have been unclear up to now, which will consequentially prevent a full understanding of the hydrological cycle of the Karst region and hinder the rational utilization of the inherent limited water resources in this region. To solve the above problem, three types of hillslopes with typical land uses (including bushland, grassland, sloping land) are to be selected as our study objects in this project to achieve a deeper understanding of the subsurface flow generation and development machanism in this area. After vegetation and soil profiles investigation, soil hydrological components including subsurface flow of in situ experimental plots (2m × 1m) will be observed in the upper, middle, and lower slope positions under both simulated and natural rainfall events. During the experiments, the comprehensive methods combining the traditional hydrological monitoring methods with the techniques of stable oxygen and hydrogen isotope tracer as well as the ground-penetrating radar are to be adopted to investigate and evaluate the subsurface flow. Based on the above experiments, we attempt to clarify how plant-soil-rock coupled architecture and deep percolation influence on the subsurface flow processes of Karst region of southwestern China, and to investigate how subsurface flow response to environmental factors, such as vegetation coverage, rainfall intensity, rainfall amount, rainfall duration, and initial soil water content, etc. After achieving this project, we intend to reveal the generation and development characteristics of subsurface flow and its main driving machanism on hillslopes in Karst region of southwestern China. The results will provide scientific basis for the rational land use planning and rocky desertification control in karst region of southwestern China.