But
- Soil parameters, C, ɸ, T are uncertain and spatially variable.
- Recharge parameter R is spatially and temporally variable.
Assume Uniform Probability Distributions
![graph](/hydrology/images/agu98sinmap/slide-6-graph.png)
C ~ U (C1, C2)
R/T ~ U(x1, x2)
tanɸ ~ U(t1, t2)
R/T ~ U(x1, x2)
tanɸ ~ U(t1, t2)
Define Stability Index
SI = Prob(FS > 1)
Slide 6 of 14