Assessment and development of pedotransfer functions to estimate soil saturated hydraulic conductivity in arid soils with application to GIS mapping in the Al-Ahsa Oasis, Saudi Arabia

Abstract

L-AHSA is one of the oldest and largest agricultural regions in Saudi Arabia. It was determined that thirty soil samples representing the majority of soil types within the region were collected and analyzed for their physical and hydraulic properties in a laboratory, including particle size (sand percent, silt percent, clay percent), saturation percent (θs), bulk density (ρ), calcium carbonate percent (CaCO 3 ), Field capacity (FC), wilting point (WP), and saturated hydraulic conductivity (Ks). A comprehensive statistical analysis was conducted to develop a pedotransfer function (PTF) to predict potential relationships between physical properties and Ks values based on correlation, stepwise multiple linear regression, mean square error (MSE), root mean square error (RMSE), t-test, and Nash-Sutcliffe efficiency (NSE). In a stepwise analysis, both sand and ρ highly influence the outcome. A significant correlation was found with Ks equal to (0.755), MSE equal to 0.045, RMSE equal to 0.194, and satisfactory NSE equal to 0.581. Using the spatial interpolation technique of the GIS map program, a new model was applied to more than 500 points of soil data in order to develop a new spatial pattern map based on the Ks value. The map is designed to provide an easy-to-read and quickreach guide for environmental researchers and engineers in determining the Ks value in the studied area in Al-Ahsa Oasis.