The soil leakage ratio in the Mudu watershed, China

Abstract

Soil leakage in karst areas is an important geomorphic agent of environmental interest. There are several viewpoints concerning soil leakage ratios. One viewpoint states that the soil leakage ratio is high in karst regions, whereas others consider that it is very low. This paper’s objective is to describe the soil leakage phenomena qualitatively and quantitatively in the Chongqing Karst, China, by conventional methods such as monitoring runoff plots and paint traces drawn on piles and walls found within runoff plots, and by measuring the activity of the isotope 137Cs at small, medium, and large spatial scales. This paper’s results show that soil-filled karst cracks occurred at a small spatial scale with soil leakage ratios ranging from about 3% to about 34% at two abandoned quarries and six soil profiles with rock (karst) crack development. The soil leakage ratio was almost zero at the medium spatial scale. The soil leakage ratio was 4.50% and the surface-soil erosion ratio was 95.50% of the total soil erosion at the large spatial scale. It is concluded that soil leakage ratios in the study area were low at a large spatial scale, and that cracks in karst were filled with soil at small spatial scales. This paper’s results indicate that soil leakage phenomena vary depending on the processes acting at the small, medium, and large spatial scales.