The shadows are good, but the tree continue no implementen in the image, ithink need broken the terrain down the tree and add some details.
About the water... i not like the water. Seems a window ¿?. For the water i put a reflection of the image how now but with waves, and the line of the water not straight, with curves.
For exameple the line of the water now:
___________
With curves:
_/\___/\_/\___/\__
I dont know if i explain very well with all, i hope help you.