Good morning, everyone. Today we're going to discuss the water cycle, but I want to focus on a less obvious aspect: groundwater. While surface water like rivers and lakes is visible, groundwater is stored underground in porous rocks called aquifers. However, not all aquifers are the same. Some, called confined aquifers, are sandwiched between layers of impermeable clay or rock, which creates pressure. This pressure can cause water to rise naturally when a well is drilled, forming an artesian well. In contrast, unconfined aquifers are closer to the surface and are recharged directly by rainfall. But here's the key point: over-extraction of groundwater for agriculture has led to significant drops in water tables in many regions, such as parts of India and the United States. This can cause land subsidence and saltwater intrusion in coastal areas.