Factor Equation Description Reference
R
\(R=\sum_{i=1}^{12}{1.735\times 10^{\left[1.5lg\left(\frac{P_{i}^{2}}{P}\right)-0.08188\right]}}\) (2)
Pi: mean monthly rainfall (mm) P: mean annual rainfall (mm)
Prasannakumar et al. (2011)
K
\(K=0.1317\times K_{1}\times K_{2}\times K_{3}\times K_{4}\) (3) And, \[K_{1}=0.2+0.3exp\left\{-0.0256SD\left[1.0-\left(SI/100\right)\right]\right\}\] \[K_{2}=\left[SI/\left(CL+SI\right)\right]^{0.3}\] \[K_{3}=1.0-\left\{0.25C/\left[C+exp\left(3.72-2.95C\right)\right]\right\}\] \[K_{4}=1.0-\left\{0.7SN/\left[SN+exp\left(-5.51+22.9SN\right)\right]\right\}\] SD: sand fraction (%) SI: silt fraction (%) CL: clay fraction (%) C: organic carbon fraction (%) SN: 1-SD/100
Yang et al. (2003)
L&S
\(L=\left(\lambda/22.13\right)^{m}\) (4) \(S=\left\{\begin{matrix}10.8sin\theta+0.03\ \ \theta<9\%\\ 16.8sin\theta-0.50\ \ \theta\geq 9\%\\ \end{matrix}\right.\ \) (5) And, \[m=\beta/\left(1+\beta\right)\] \[\beta=sin\theta/\left[3\left(\text{sinθ}\right)^{0.8}+0.56\right]\] λ: horizontal projection slope length m: variable slope length exponent β: a factor that varies with slope gradient θ: slope angle (%). McCool et al. (1989) Zhang et al. (2013)
C
\(C=\left\{\begin{matrix}1\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 0\leq FVC\leq 4.9\%\\ 0.221-0.595lgFVC\ \ \ \ \ FVC\geq 4.9\%\\ \end{matrix}\right.\ \) (6) And, \[FVC=\left(EVI-\text{EVI}_{\min}\right)/\left(\text{EVI}_{\max}-\text{EVI}_{\min}\right)\] FVC: the fractional vegetation cover EVImin and EVImax: the minimum and maximum EVI values of the whole study area during the study period
Liu et al. (1999)