Sensitivity of infiltration modelling to temporal resolution of rainfall data

Abstract

AbstractThe sensitivity of infiltration predictions by Hydrus‐1D and Green‐Ampt models to rainfall discretisation was investigated by assessing the accuracy of infiltration predictions with rainfall rate profiles at step sizes D between 2 and 1440 min. Five peak rainfall profiles and one sine‐wave rainfall profile, all with a cumulative rainfall amount of 28.8 cm and a duration of 24 h were used. Discrete rainfall profiles were generated based on the peak rainfall profiles for several step sizes. The rainfall profiles were evaluated in a sandy loam with a high saturated hydraulic conductivity and a silt loam with a low saturated hydraulic conductivity for two initial pressure heads. For both models, insensitivity was found below a critical step size Dcrit, whereas high sensitivity was observed above it, Dcrit depending on soil hydraulic conductivity and rainfall peak intensity, regardless of initial pressure head. In the sandy loam, Dcrit was 20–30 (high‐intensity peak) and 70 min (low‐intensity peak); in the silt loam, values were 100 and 200–300 min, respectively. Therefore, rainfall data from common weather station data at D = 60 min allow accurate estimates of infiltration only in low‐conductivity soils or for low‐intensity rainfall. The disaggregation of daily cumulative rainfall into sine‐wave profiles improved predictions in more conductive soils. Results indicate that higher saturated hydraulic conductivity and intensity peak rainfall rate require smaller values of D for the accurate modelling of infiltration with Hydrus‐1D and Green‐Ampt models.Highlights Temporal resolution of rainfall data is important in infiltration modelling. Temporal resolution of rainfall data affects Green‐Ampt and Hydrus‐1D predicted infiltration Green‐Ampt and Hydrus‐1D cumulative infiltration predictions are insensitive for rainfall resolution ≤20 min Predictions are more sensitive to rainfall resolution >20 min in soils with higher hydraulic conductivity.