TEMPORAL VARIABILITY OF SOIL SURFACE CRUST CONDUCTIVITY

The temporal variability of soil surface crust conductivity is studied on two different time scales. Undisturbed soil samples were taken fro m four different plots in order to study the infiltration-runoff behav iour in the laboratory. A simulation model was applied to compute surf ace runoff and soil suction profiles. Taking best fit between the comp uted and experimentally measured data hydraulic properties of the soil and of the crust were estimated. In nearly all of the 22 analyzed soi l samples, crust development could be observed in the laboratory. Beca use sampling was repeated during the vegetation period it was feasible to discern if decreases in hydraulic conductivity of the crust occurr ed in the long term. The data showed no long-term decreases although i n the laboratory, crust development was observed in nearly every case. If short and intensive rainfall events were to be simulated, the init ial condition of the crust would be the most sensitive parameter for t he runoff amount.