Background Soil and water leakage is a specific soil and water loss issue in karst areas, it is most serious in the karst area of Southwest China, and causes severe resource and environmental issues such as soil loss from farmland, rocky desertification, depression water logging and pollution to cave landscape. Because the karst structures in Southwest China are complex and soil leakage studies were begun after the 21st century, the theoretical and technologic system of soil and water leakage have not been formed. Based on systematically analyzing relative papers, this review aims to present the main research progresses, shortages, and the next research directions on soil and water leakage in the karst areas of Southwest China.

Methods In order to accurately grasping the important research progresses and shortages, the authors took soil and water leakage, karst, soil and water conservation, and Southwest China as the key words, and collected over 200 relative papers from all literature database at home and abroad. The authors chose 76 papers as references of this review; after focused the four important aspects of this paper such as feature, processes, monitoring and evaluation, and mechanism of soil and water leakage in the karst areas of Southwest China, and excluded many papers that were not closely relevant to this review's target.

Results 1) This review clarified four features on the soil and water leakage of karst areas in Southwest China, i.e., geological concealment of soil and water leakage processes, relative low soil loss tolerance, geomorphological differences of soil and water leakage, and difficulty of treatment project of soil and water leakage. 2) This review revealed the importance of systematic studies on the soil and water leakage processes in karst ground river basin after concluding research progresses on processes, monitoring, evaluation and influence factors of the soil and water leakage, . 3) Three defects of present studies on the soil and water leakage in karst areas of Southwest China are gave, especially on quantitative characterization of rock-soil-fissure fabric, key processes and mechanism of the soil and water leakage, and evaluation models of the soil and water leakage. 4) Targeting national goals on prevention and treatment of the soil and water leakage in the karst areas of Southwest China and the international frontier research directions, this review provides three important research directions, i.e., network studies of the soil and water leakage of karst critical zone, systematic researches on key processes of the soil and water leakage, and construction and usage of evaluation models of the soil and water leakage.

Conclusions The soil and water leakage issue in the karst areas of Southwest China is the most typical and serious in China and even in the world. Though some research progresses have achieved, the theoretical and technological system for soil and water leakage have not been established. Systematic study on the soil and water leakage of the karst critical zone in Southwest China is an important research direction.