Effects of distribution patterns of karst landscapes on runoff and sediment yield in karst watersheds

Aquatic karst landscapes are highly heterogeneous and vulnerable to environmental conditions due to carbonate rock dissolution by flowing water, freshwater movement and sediment transport. However, the landscape metrics commonly used in landscape ecology do not consider the spatial distribution of carbonate rocks in karst watersheds because these metrics are derived from land use/land cover maps. Therefore, this study investigated the effects of distribution patterns of karst landscapes on annual runoff and sediment yield in 40 heterogeneous karst watersheds in southwest China. The results show that the distribution patterns of karst landscapes significantly influenced annual runoff and sediment yield. A general linear model explained 74% of the runoff variations, indicating that the distribution pattern was the principal factor affecting runoff. Although these patterns significantly affected sediment yield, the general linear model accounted for only 52% of the sediment yield variations. Thus, the distribution patterns showed larger effects on runoff than sediment yield. This may be because landscape metrics of karst distribution patterns could not fully reflect the three-dimensional (3D) hydrogeological structure of karst watersheds. It is necessary to investigate the effects of 3D hydrogeological structures and hydrological and sediment connectivity on sediment yield. This will facilitate a more in-depth understanding of soil erosion mechanisms in karst watersheds.