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

Abstract

Accurate saturated hydraulic conductivity (Ksat) predictions are critical for precise water flow estimations. Pedotransfer functions (PTFs) have been used to estimate Ksat based on soil structural and textural properties. However, PTF accuracy must be validated with observed Ksat values to improve confidence in model predictions. A study was conducted in the seasonal wetlands of a representative mixed land-use watershed in West Virginia (WV), USA. The observed data included soil characteristics and observed piezometric Ksat using slug tests. Soil texture was predominantly sandy, and the observed average Ksat ranged from 35.90 to 169.64 m/d. The average bulk dry density (bdry) increased, while porosity and volumetric water content decreased significantly with a depth to 45 cm (p < 0.05). The degree of saturation varied significantly between monitoring sites (p < 0.05). A Pearson correlation matrix and Principal Component Analysis (PCA) revealed that Ksat was more connected to soil textural properties, specifically clay. Single parameter PTFs that estimated Ksat as a function of clay content performed better (ME = −90.19 m/d, RMSE = 102.87 m/d) than the PTFs that used silt or sand percentages (ME= −96.86 m/d, RMSE = 108.77). However, all five PTFs predicted Ksat with low accuracy (RMSE > 100 m/d), emphasizing the need to calibrate existing PTFs with observed data or develop site-specific PTFs. These results provide valuable insights into Ksat estimation in riparian wetlands of mixed land-use watersheds and are a helpful reference for land managers and future work.

SWAT Model Performance Using Spatially Distributed Saturated Hydraulic Conductivity (Ksat) and Varying-Resolution DEMs

“…The field Ksat data collection did not include subsurface soil Ksat values. Ksat may vary with soil depth, and this omission could potentially affect model predictions, as more observed data might enhance the model performance and reduce model simulation uncertainty [20,25,31,69,79]. In addition, this study showed that 1 m DEM could provide a more detailed and accurate analysis in this study relative to coarser DEMs.…”

“…Furthermore, Ksat is highly spatially variable and is greatly influenced by soil texture, compaction, and other factors [8][9][10]. There are many different techniques to directly determine Ksat in the field and laboratory (e.g., pumping, permeameter tests, and slug tests), as well as indirect methods: pedotransfer functions (PTFs), artificial neural networks (ANNs), support vector machine (SVM) models, and hydrological modeling [6,9,[11][12][13][14][15][16][17][18][19][20]. All methods of estimating Ksat often provide varying results due to differences in measurement and calculation methods.…”

Surface Water (SW) and Shallow Groundwater (SGW) Nutrient Concentrations in Riparian Wetlands of a Mixed Land-Use Catchment

“…The study was conducted in seasonally flooded palustrine emergent riparian wetlands of a second-order reach in the West Run Watershed (WRW) located in northeastern Morgantown, West Virginia (WV), USA (Figure 1). The study reach drains into the third-order West Run Creek, a Monongahela River tributary [31]. The soil texture of the study reach was predominantly sandy, and the observed average saturated hydraulic conductivity (Ksat) ranged from 35.90 to 169.64 m/d [31].…”

“…The study reach drains into the third-order West Run Creek, a Monongahela River tributary [31]. The soil texture of the study reach was predominantly sandy, and the observed average saturated hydraulic conductivity (Ksat) ranged from 35.90 to 169.64 m/d [31]. The soil's average dry bulk density, porosity, and degree of saturation were 1.27 g/cm 3 , 0.57, and 0.94, respectively [31].…”

Assessment of Saturated Hydraulic Conductivity with Using Soil Particle Size Distribution: A Comparative Study of Constant Head and Falling Head Methods

“…A previous study by Phaneuf et al, (1999) reported that, irrespective of land practices, a large portion of water flow is transported by a small portion of the soil volume, demonstrating that the spatial hydraulic characteristics of soils are highly variable. The K sat measurements should therefore be evaluated carefully to ensure that the values obtained are accurate and appropriate for the intended use (Abesh and Hubbart 2023).…”