Could you please help me understand how to use rhino and grasshopper to do forecast simulation model？
Thanks.
like… weatherforcast? 
maybe you can explain a bit more in detail what you need. i am afraid the two catchphrases forecast and simulation can be pretty broad…
If I know the basic situation of the current site desert, including soil conditions, climate and other factors, if I adjust its rain conditions, the desert may become a forest, how can I simulate this scene?
are you referring to the already existing project in china to reduce the gobi desert? that is indeed an interesting topic. without being of much help in setting something like this up but generally just to elaborate on what i means to simulate, when your aim for forestation what exact parameters do you have in mind other than soil, climate or even to some part adjustable rain conditions?
in the end it is about setting up the parameters which have to be brought into a formulated relation and for this we would have to understand the exact parameters. maybe it would make more sense to program a component in grasshopper with python, c#, c++ for instance which processes your information rather than setting everything up with grasshopper components.
sorry if i am not much of a help, but to get good help it would be good to show as much as you have and to elaborate as thorough as possible for somebody to hopefully chime in and help.
have you got any grasshopper experience? is there anything you have started with?
I use grasshopper mainly for modeling and human flow simulation. I know very little about vegetation simulation. Now I think if the rain situation changes, some deserts will become oases. I want to simulate it