水不足
When there is a geographic and temporal imbalance between the demand of freshwater and its availability, that is known as water scarcity. In this regard, scarcity can be defined as either the scarcity in availability due to physical shortage or scarcity in access due to lack of adequate infrastructure. Water scarcity is the consequence of both natural and man-made causes. Water scarcity or lack of safe drinking water (physical water scarcity) is one of the world's leading problems affecting more than 1.1 billion people globally, meaning that one in every six people lacks access to safe drinking water.