Alternatively, modelling of the unsaturated flow during the initial infiltration of water could be used.
The initial infiltration rate, final infiltration rate and moisture contents fluctuate from 96 48 mm/h, 15 11 mm/h to 7.98 1.93%, respectively, for the study area.
Soil permeability is one of the most important soil physical characteristics influencing the water infiltration rate, and main indicators for soil permeability are the initial infiltration rate and the steady infiltration rate.
Therefore, Eq. 1 could be used to forecast the initial infiltration rate in the sandy mining subsidence area.
K_{t} = a times t^{ - b} (1 where K t is the instantaneous infiltration rate (cm/min); t is the infiltration time in min; a and b are empirical parameters that reflect the initial infiltration rate and the rate of decrease in the infiltration rate, respectively.
This study considered the first 5 min to be the initial infiltration time and the moment when the permeation amount per unit of time reached stabilization to be the steady infiltration time.
According to the above analysis, the regression model based on the initial infiltration rate and the three impact factors was significant with high correlation.
The Horton's infiltration model (Horton 1941) is expressed as follows: m, =, left( {m_{0} -, m_{text{c}} } right)e^{ - kt} +, m_{text{c}}, (3)where mc is the steady infiltration rate (LT−1); m0 is the initial infiltration rate (LT−1), and t is time (T).
The soil stable infiltration rate presented the order DSA3 (2.89 mm/min) > SGB (2.65 mm/min) > DSA2 (1.89 mm/min) > DSA1 (1.64 mm/min) > CR (0.45 mm/min), while the soil initial infiltration showed the order DSA1 > DSA3 > SGB > DSA2 > CR.
