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Highlights

Effective hydraulic conductivity (K_e) predictive equations in all RHEM versions have satisfactory performance.

Abstract. Effective hydraulic conductivity (K_e) is an important parameter for the prediction of infiltration and runoff by the Rangeland Hydrology and Erosion Model (RHEM). Three sets of equations to predict K_e have previously been used in RHEM. These equations are mainly based on rainfall simulation data representing undisturbed sites and have not undergone comprehensive evaluation for various rangeland conditions, particularly after disturbances. The goal of this research was to evaluate these equations using independent data obtained from rainfall simulations conducted at multiple rangeland sites. Additionally, we developed and evaluated a new set of K_e predictive equations applying readily measurable cover and soils data spanning a wide range of vegetation, soil textures, and disturbance conditions. The results show that all previous K_e equations in RHEM have a “satisfactory” performance with index of agreement (d) > 0.75 and R² > 0.4. The new K_e approach resulted in “very good” performance with d > 0.9 and R² > 0.5. The new set of equations enhances RHEM for applications over broader rangeland conditions, including sparse vegetation cover following disturbances or community transitions.