Infiltration Model for Center Pivot Irrigation on Bare Soil

Abstract

The marked reduction in infiltration rate caused by formation of a soil surface seal due to water droplet impact on bare soil is a well known phenomenon but is rarely considered in infiltration models, especially under center pivot irrigation. The objective of this study was to develop a soil infiltration model for center pivot sprinkler irrigation that incorporates the transient reduction in soil surface seal hydraulic conductivity as affected by soil and sprinkler characteristics and investigate the effect soil sealing characteristics and sprinkler selection have on infiltration depth. A sealing soil infiltration model was developed using an explicit finite difference solution scheme with a transient soil seal formation model, which is unique from other studies in that it explicitly uses droplet specific power as the driving factor for formation of a soil surface seal. The model was calibrated to four specific soils then applied to center pivot irrigation for five common center pivot sprinklers to evaluate the effect sprinkler selection has on infiltration depth. Due to the high susceptibility of the soils to surface sealing from water drop impact, the sprinkler with the largest wetted diameter was predicted to maximize infiltration depth.