Here is an example where velvia just can't handle the range very well (although you could've let the highlights get a stop or so hotter, I am guessing). What you do in this case is preflash the frame. Or try astia.... or use neg film Velvia 50 is not the conventional choice for a sunny day like this. Mind you, there is probably a decent amount of shadow detail there, but if you scan, you have to multiscan the snot out of it to get it.