In order to explore the water infiltration characteristics and optimal infiltration model of arsenic sandstone soil (gray white

mixed color

purplish red) with different textures under different slopes (5°

10°

20°

30°)

the characteristics of soil water infiltration and fitting results were compared and analyzed by indoor simulated soil column method. The results showed that:(1) The soil bulk density of different slopes in the study area is 1.513~1.737 g/cm3. The soil infiltration capacity of gray white arsenic sandstone under 30° slope was strong

and the soil infiltration capacity of purple red arsenic sandstone under 5° slope was weak. (2) In the process of one-dimensional vertical infiltration of arsenic sandstone soil

the initial infiltration rate was 2.000~8.600 cm/min

and the stable infiltration rate (0.160~1.800 cm/min) was reached after the infiltration time was 3.500~5.000 min. The infiltration rate and wetting front migration rate decreased with time in a power function. The smaller the slope and the darker the color was

the lower the infiltration rate and cumulative infiltration rate was

and the slower the migration of wetting front was. The values of initial infiltration rate

stable infiltration rate

initial wetting front migration rate

and stable wetting front rate all decreased with the decrease of slope gradient and the deepening of arsenic sandstone soil color. (3) Kostiakov model and Philip model fit well the results of soil water infiltration in arsenic sandstone area

and the determination coefficients were more than 0.900. The average value of the decision coefficient of Kostiakov model was 0.948

and the fitting effect was the best. The average value of Philip model determination coefficient was 0.937

and the fitting effect was the second. The average value of the determination coefficient of Horton model was 0.688

and the fitting effect was poor. Through the mean absolute error (MAE)

root mean square error (RMSE)

percentage of deviation (PBIAS)

and Nash efficiency coefficient (NSE)

it was verified that the simulated values of Kostiakov model and Philip model have little difference and high degree of coincidence with the measured values.