Rivers supplied not only water for the colonist, but transportation which also led to trade. Also a lot of wild life are around river which gave them food also weather it be fish in the rivers or animals that come to the river to drink. So rivers provided water, transportation, and food.
It's hard for me to make out what is all in the photograph because it's grainy, so hopefully this still helps!
Adaptation is 4. 100% im an expert at this stuff