Prediction of spatial saturated hydraulic conductivity at the upper soil layer using soil class and terrain attributes

MD Moudud Hasan, Ajoy Kumar Saha, Md. Redwan Ahmad Khan, Md. Al Amin

Research outputpeer-review


The knowledge of soil hydraulic properties is indispensable to solve many soil and water management problems related to agriculture, ecology, and environmental issues in water. This research aimed to generate the saturated hydraulic conductivity (Ks) information of topsoil from soil class and terrain attributes (elevation, roughness, slope, terrain ruggedness index (TRI), topographic position index (TPI), and flow direction) using multiple linear regression (MLR) and support vector regression (SVR) techniques to develop a spatial distribution map of Ks for an agricultural landscape. Sixty-five cores of soil sample (diameter 5 cm and length 10 cm) were collected from the topsoil layer (0–10 cm) from the agricultural field in different locations (Upazilas) of the Sylhet region (3452 km2) in Bangladesh and conducted laboratory tests following Darcy’s constant head method. The topsoil was clay or silt clay, having very low Ks values. The mean of Ks for the agricultural soils is 1.70 × 10–06 cm/s and varied significantly (p < 0.01) among different Upazilas (sub-district). To generate the topsoil layer’s Ks values, the developed MLR model (with R2 = 0.598 and RMSE = 1.12 × 10–06 cm/s) and SVR model (with training R2train=0.64, RMSE = 1.22 × 10–06 cm/s and NSE = 0.58 and testing R2test=0.73, RMSE = 8.19 × 10–07 cm/s, NSE = 0.71) were found suitable compared to simple interpolation methods. The SVR model performed better in the modeling process than the MLR based on the goodness of fits parameter. However, the SVR model underestimates the higher Ks values in both training and testing stages. In contrast, the MLR model was found to be more balanced. Finally, the spatial variability map of Ks for the topsoil layer can be generated from soil texture information and terrain attributes for facilitating agro-hydrological model development in a data-limited area.
Original languageEnglish
Pages (from-to)1-15
Number of pages15
JournalModelling Earth Systems and Environment
StatePublished - 26 Oct 2021

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