Evaluating and modelling splash detachment capacity based on laboratory experiments

Abstract Splash erosion is recognized as an important process of water erosion on agricultural land, but evaluating and modelling splash detachment capacity on steep slopes using loessial soil were not fully studied. The objectives of this study are: (1) to evaluate the effects of slope gradient ( S ) and rainfall intensity ( I ) on splash detachment capacity ( SDr ), (2) to select the key rainfall physical parameters and hydraulic parameters affecting splash detachment capacity, (3) to establish new and more accurate experimental models between splash detachment capacity ( SDr ) and these key parameters on steep slopes for loess regions. The experiment was conducted at slopes of 12.23%, 17.63%, 26.8%, 36.4%, 40.4% and 46.63% under rainfall intensities of 48, 60, 90, 120, 138 and 150 mm h −1 , respectively, using simulated rainfall. Results showed that the equation between splash detachment capacity ( SDr ) with both parameters of rainfall intensity ( I ) and slope gradient ( S ) (i.e. SDr  = 0.000126 ln (0.36 S −0.3 I 1.3  − 14)) could predict SDr well with R 2  = 0.85 and Nash–Sutcliffe model efficiency (NSE) = 0.71. SDr was more sensitive to rainfall intensity than to slope gradient. The rainfall kinetic energy ( KE ) was the key rainfall physical parameter and the mean flow depth ( h ) was the key hydraulic parameter affecting SDr . The equation between SDr with both parameters of KE and h (i.e. SDr  = 0.000164 ln (0.0031 KE 1.13 h −0.3  − 4.5)) could satisfactorily predict SDr with R 2  = 0.85 and Nash–Sutcliffe model efficiency (NSE) = 0.81. The new equations (i.e. SDr  = 0.000126 ln (0.36 S −0.3 I 1.3  − 14) and SDr  = 0.000164 ln (0.0031 KE 1.13 h −0.3  − 4.5)) could help in controlling water erosion in the loess region of China.