1. What problems did scientists discover regarding groundwater around the world

Answer: groundwater depletion

Explanation:

Excessive groundwater pumping is that the water table, below which the ground is saturated with water, can be lowered. For water to be taken from the ground, water must be pumped from a well that reaches below the water table. If groundwater levels decline too far, then the well owner might have to deepen the well, drill a new well, or, at least, attempt to lower the pump.