Spatial variation of saturated hydraulic conductivity in a riparian zone: A case study of the Baoan Lake in Hubei Province, China

Abstract

Saturated hydraulic conductivity (Ks, [L T−1]) is an important physical property of soil in riparian zones that influences water and solutes exchange between surface and subsurface water systems. Spatial variation of Ks should be considered in the assessment of its effects on the interaction of surface and subsurface waters in riparian zones. In this study, 133 disturbed and 399 undisturbed soil samples were collected from the riparian zones of the Baoan Lake in Hubei Province, China. Spatial distribution patterns of Ks in rural riparian zones were determined, and their variabilities were analyzed to understand the influences of soil, land use, vegetation, hydrological, and geological factors. The spatial variations of Ks indicated the following: (1) the mean Ks value decreased with soil depth in the riparian zone; (2) Ks values showed increasing and fluctuating patterns in the lateral direction of the lakeshore; (3) the study region was divided into high-, medium-, and low-permeability areas; and (4) Ks values of influent tributaries decreased from upstream to downstream reaches in the periodic inundation zone (Zone 1), whereas the effluent tributary exhibited the opposite trend. Permeabilities were low at the confluences of the lake and its tributaries compared to that of the other reaches of the same tributaries. Riparian soil displayed fast to slow infiltration patterns between 0–20 cm and 20–40 cm soil layers. The degree of vertical variation caused by the periodic inundation of water was smaller. Permeability based on land use decreased in the order of farmland, forests, and fishponds. Studying the permeation of riparian zones and associated ecosystems provides a scientific basis for their comprehensive management and efficient utilization, and this work provides a framework for the same through a case study.