How is the elevation of land measured?
Precise land survey elevation generally makes use a level together with crosshairs to view a levelling rod placed on the surface of the ground and a telescope to determine the elevation of a point (Dai et al., 2018). Conventionally the initial point of measurement is usually at sea level, which is arguably the starting point (0)
Why is it measured from that point?
Conventionally the sea level acts the baseline point for assessing the extent of an elevation and Earth’s depth. Since the ocean is one unbroken mass of water, its surface is inclined to rest the same level all through the Earth. Nonetheless, strong currents, tropical winds, discharges from other water sources, including shifts in temperature and gravity alter the true levelness of the ocean surface (Dai et al., 2018).