Marvita lives near a river, but can't afford easy access to fresh water. she suffers from scarcity.

I believe the answer is: Economic scarcity

Economic scarcity refers to a situation where the amount of economic goods (such as food and water) are not enough to fulfil the demand of the people in a certain area. These scarcity could be caused by several factors, whether it's seasonal, political, or even by human mistakes when we are exploiting the environment.