Development of Pedo-Transfer Functions for the Saturated Hydraulic Conductivity of Forest Soil in South Korea Considering Forest Stand and Site Characteristics

Abstract

The saturated hydraulic conductivity (Ks) is one of the most important soil properties for many hydrological simulation models. Especially in South Korea, analyzing the Ks of the forest soil is essential for understanding the water cycle throughout the country, because forests cover almost two-thirds of the whole country. However, few studies have focused on the forest soil in the temperate climate zone on a nationwide scale. In this study, 1456 forest soil samples were collected throughout South Korea and pedo-transfer functions employed to predict the Ks were developed. The non-linearities of the soil and topographic features were considered with the pretreatment of variables, and the variance inflation factor was used for treating the multicollinearity problem. The forest stand and site characteristics were also categorized by an ANOVA and post hoc test due to their diversity. As a result, the Ks values were different for various forest stands and site characteristics, which was statistically significant. Additionally, the model performance was higher when both soil properties and topographic features were considered. The sensitivity analysis showed that the Ks was highly affected by the bulk density, sand fraction, slope, and upper catchment area. Therefore, the topographic features were as important in predicting the Ks as the soil properties of the forest soil.

Evaluation and Development of Pedo-Transfer Functions for Predicting Soil Saturated Hydraulic Conductivity in the Alpine Frigid Hilly Region of Qinghai Province

“…It is worth mentioning that the K S of the coniferous pure forest was generally lower than that of coniferous and broad-leaved mixed forest. Lim et al analyzed 1456 soil samples from South Korea and found that K S in the broad-leaved mixed forest was significantly higher than that in the coniferous pure forest, which coincides with the results of this study [32]. Firstly, the roots of broad-leaved tree species were more widely spread laterally and produced a large number of small root branches, resulting in more developed soil pores than in coniferous forests [33].…”

Estimating Unsaturated Hydraulic Conductivity in Unsaturated Soil Using Soil Moisture Sensors

“…The Ks is one of the essential parameter in order to predict K. In this study, it was estimated using falling-head approach [22]. Soil bulk density affects the Ks [23]. The Ks of different b were calculated using Eq.…”

A Comparison of Saturated Hydraulic Conductivity (Ksat) Estimations from Pedotransfer Functions (PTFs) and Field Observations in Riparian Seasonal Wetlands

“…Despite the method yielding a relatively quick and inexpensive determination of Ksat, PTFs often do not include the spatial and temporal variability of soil water movement related to land use, land cover, and vegetation [22][23][24][25]. Previous studies showed that the reliability of PTFs is often limited in regions with similar soil properties and land-use history [17,[24][25][26]. Lim et al [25] determined the usefulness of six PTFs for Ksat prediction in forested soil of South Korea and concluded that observed Ksat was 10 times larger than Ksat estimated by PTFs.…”

“…Previous studies showed that the reliability of PTFs is often limited in regions with similar soil properties and land-use history [17,[24][25][26]. Lim et al [25] determined the usefulness of six PTFs for Ksat prediction in forested soil of South Korea and concluded that observed Ksat was 10 times larger than Ksat estimated by PTFs. Similarly, Petryk et al [26] analyzed the predictive accuracy of 15 PTFs in highly eroded loess soil samples and suggested a need to develop PTFs using local soil data.…”

“…While previous studies have validated PTFs across different land-use practices [8,22,25], there is a notable gap in validating and comparing these functions in seasonal riparian wetlands of mixed land-use watersheds, highlighting a need for future research. The relevance of this research extends beyond understanding the predictive accuracy of PTFs.…”