In this context, "alter" means to change or modify something. When it comes to physical geography shaping cultures but also being altered by cultures in return, it implies a reciprocal relationship where both influence each other.
Related terms
Human-Environment Interaction: The ways in which humans modify, adapt to, and depend on their environment.
Land Use: The various ways in which land is utilized by human activities, such as agriculture, urbanization, or conservation.
Sustainable Development: Balancing economic growth with social and environmental considerations to meet the needs of the present without compromising future generations.