Spatiotemporal variation characteristics and water flow path of soil moisture of the critical zones fissures in karst area
YANG Jixiang
ZHANG Zhicai
CHEN Xi
LIU Xiuqiang
XIE Yongyu
PENG Tao
CHEN Bo
Abstract：The dynamics of soil moisture in the critical karst zone fissures and their controlling factors form the foundation for studying ecological hydrological processes in this region.Analyzing the spatiotemporal dynamics of soil moisture within soil-rock fill structures and elucidating the controlling effects of changes in water flow pathways will provide scientific basis for research on ecological hydrological processes in karst regions and the efficient utilization of water resources.The study area is located at the Puding Karst Ecosystem Research Station in Guizhou Province,southwest China,situated on the watershed between the Yangtze River and Pearl River systems of the Guizhou Plateau.It is the core region of the southern Chinese karst landscape,which is one of the three major contiguous karst landform regions globally.
In the study,representative critical karst zone soil-rock filling structure profiles were selected within the station,and a soil-rock fissure moisture observation system was established.Using moisture monitoring probes installed at different depths,high-resolution spatiotemporal observations of fissure soil moisture were conducted.By observing Soil Water Content(SWC)at different depth levels,soil-rock interface water content(S-R),and fine rock soil water content(RWC),the study investigated the spatiotemporal variation patterns of soil moisture in different types of fissures within the critical karst zone.By combining rainfall characteristics with the response patterns of fissure soil water content,the study revealed the control mechanisms of rainfall infiltration processes on fissure soil moisture.The results indicate that the dynamic changes in soil moisture in fine fissures are significantly higher than those in large fissures far from the soil-rock interface,with higher moisture content and better water-holding capacity,providing a reserve water source for vegetation growth.Due to the rapid infiltration influenced by the fissure network or soil-rock interface,fissure soils connected to rapid pathways in the critical karst zone can be rapidly replenished with moisture,exhibiting more intense moisture change dynamics.In contrast,soil in fissures controlled by slow infiltration exhibits slow water replenishment and relatively mild moisture dynamics.Additionally,rainfall infiltration pathways vary with dry-wet conditions and fissure development,further complicating the spatiotemporal variability of soil moisture in fissures.Rainfall characteristics significantly influence moisture changes in fissure soils during rainfall events.In single-peak rainfall events,moisture content in all types of fissure soils is significantly higher than in continuous rainfall events.Influenced by rapid flow channels at the soil-rock interface,the soil moisture content in the middle and lower layers of large fissures,as well as the soil moisture content in small fissures in the middle layer,respond rapidly to rainfall.The developed rock fissure network increases the connectivity between fissures and the surface,accelerating rainfall infiltration recharge to fissures.Rainfall intensity regulates water flow pathways.As rainfall intensity increases,the hydrological connectivity of the soil-rock interface rises,and its role in water transport process during rainfall infiltration gradually strengthens.Especially under heavy rainfall conditions,lateral hydrological connectivity within the soil-rock fissure system increases,and lateral water flow processes become a key controlling factor in the moisture dynamics of fissures soils.
Keywords：karst critical zonefissure soilssoil-rock infill structureswater contentwater flow path
Publication Date：2025-10-31
Online Publishing Date：2026-01-14(First online date of this platform, not the publication date of the document)
Pages：11( 1063-1073 )