Flow hydraulic characteristics and dynamic erodibility of saline-sodic soil slopes for coastal areas under simulated rainfall conditions

Tidal flat reclamation generates several excavated saline-sodic soil slopes. However, there are limited studies on the hydraulic flow characteristics and dynamic erodibility of saline-sodic soil slopes. This study was conducted to quantify the effects of the soil bulk density (1.35 and 1.40 g cm(-3)), rainfall intensity (85, 110, and 125 mm h(-1)), and slope gradient (11 degrees, 22 degrees, and 35 degrees) on the hydraulic characteristics and soil erodibility of saline-sodic soil slopes under simulated rainfall conditions. The mean sediment loss significantly increases with the slope gradient (pr = 0.9, p < 0.01), rainfall intensity (pr = 0.6, p < 0.05), and soil bulk density (pr = 0.6, p < 0.05). The hydraulic shear stress (tau) and stream power (omega) are good sediment loss predictors for all soil bulk densities (R-2 = 0.4 and 0.6). The stream power equation S-L = K-omega (omega - omega(cr) ) outperforms both hydraulic shear stress equations [S-L = K-tau (tau - tau(cr) )(3/2); S-L = K-tau (tau - tau(cr) )]. In most cases, the soil erodibility exponentially increases to a maximum and then exponentially decreases (R-2 > 0.6). Consequently, the dynamic changes in the saline-sodic soil erodibility during a rainfall event cannot be neglected.