Definition of water level

The term "water level" can be traced back to ancient Greek times, where philosophers and astronomers known as the Pythagoreans developed the concept of hydrostatics, which explored the behavior of fluids under the influence of gravity. In this context, the term used to describe the height of the surface of a body of still water was "hivata suntaktika," which literally translates to "equipond," meaning a point at which weight is equalized. However, it was the Greeks' predecessors, the Babylonians, who first used the word "ulû" around 3000 BC to refer to the height of the water's surface in a standard container called a "gîm". Shortly after, the Chinese equivalent "shuiyí" became popular, which was adopted in the Tang Dynasty's (AD 618 - 907) maps to indicate water level changes. The meaning and use of the term "water level" evolved over time, particularly during the Middle Ages, when medieval engineers and surveyors utilized simple methods to measure and record water levels for practical purposes like observing water resources for agricultural purposes or studying the height of high tides. In the 16th and 17th centuries, scientific advancements, such as the development of the inclined plane, the barometer, and the全 Mercator projection map, facilitated more accurate measurements and led to standardized usage of "water level" in hydrological and hydrographical disciplines. Today, "water level" denotes the height of a body of water above or below a specific point, such as an elevation or the sea floor, measured with specialized equipment like staffs, staff gauges, pressure sensors, and acoustic systems. It remains a critical concept in fields related to hydrology, oceanography, meteorology, engineering, dredging, construction, irrigation, and water resources management, defining variables like inflows, tidal patterns, piezometric head, and riverflow, where quantifying data is essential to monitor and manage sustainability for society and the environment.