"开辟水道或沟渠" can be translated into English as "dig water channels or ditches".
Here, "dig" means to create a hole or channel by removing earth or other material, which accurately conveys the action of creating waterways or drainage channels. "Water channels" refers to passages for water flow, while "ditches" are narrow trenches dug for drainage or other purposes. Together, they effectively express the idea of "开辟水道或沟渠".