first I choose this picture and used for background.
step 2 of 3
then put the source image in a layer above the road, and using ctrl+t resized the river to match with the road. to do this used opacity on the source image at 50%. then gave a layer mask to the source image and with a soft brush erased the part of the picture I didnt want
step 3 of 3
now I needed to give a reflection of the road picture to the river. to do this, duplicated the road image. and then click edit-transform-flip vertical. and with free transform, placed the image over the source image until the reflection matched. put it on overlay and opacity 60%. then created a new layer filled with white, and then filter noise + overlay opacity 30%