Which best describes the impact of irrigation on the social developments of early river civilizations? some men were free to devote their time to big-game hunting, which provided surplus meats and leadership roles for the most successful hunters. disputes over land and water rights led to conflict between clans and tended to keep farming communities small. powerful leaders and political institutions emerged when large numbers of people were organized to operate successful irrigation systems. groups of farming families banded together in villages to protect each other and work the land together.