Soil hydraulic pedotransfer functions for estimating saturated hydraulic conductivity: a deep symbolic regression approach with mean shift clustering - Cheng Zhang; Zhongwang Wei; Wei Shangguan; Fan Bai; Wenzong Dong; Qiyun Xiao; Hongwei Zhao; Pingping Liu; Qingliang Li; Yongjiu Dai (Journal of Hydrology, 2026)