What is the term for the supplementation of additional water to the land?

The correct term for the supplementation of additional water to the land is irrigation. This process involves artificially providing water to crops and soil to enhance moisture levels, facilitate plant growth, and improve agricultural productivity. Irrigation is crucial in areas where rainfall is insufficient or inconsistent to support farming activities.

The other terms, while related to water, do not accurately describe the process of supplying additional water for agricultural purposes. Hydration generally refers to the process of adding water to something to maintain moisture or as a health practice, but it is not specifically used in an agricultural context. Watering is a more general term that could apply to any instance of adding water to plants but does not encompass the systematic approach that irrigation implies. Drainage, on the other hand, pertains to the removal of excess water from the land, which is the opposite of what irrigation seeks to achieve. Thus, irrigation is clearly the most appropriate term to describe the act of adding water to the land for agricultural use.