SynopsisRecords of water levels date from the first hydrospheric observations. The levels of inland and coastal waters are recorded with the use of tide gauges of various types and construction. The float-level gauge, however, is by far the most frequently used.The oldest self-recording tide gauge was constructed by Henry R. Palmer, civil engineer of the London Dock Company, in 1831. A float resting on the water is placed in a well communicating with the river. The motion of the water surface is transmitted to the recording machine by wheels and shafts which act on a pencil rack. As the water level rises and falls, by the combined motions of a clock and the tide the pencil produces a line as a function of time.Even today this principle is still used for float-level gauges. It represents the basis of the modern tide gauges for observing sea levels and their variations.In 1831 we find another construction by Mitchell, which was erected in the Sheerness dockyard. A few years later Thomas G. Bunt developed a tide gauge, which was used on the eastern bank of the river Avon near Bristol from 1837 to 1872.In 1834 the first self-recording gauge was erected in France, near Le Havre. On the other continents the first installations were established in Algiers (1834), in the United States and in India (1846), and in Australia (1858)An installation in Hamburg (1861), which was developed by F. H. Reitz the engineer, is identified as the first German construction.In 1870 fifteen tide gauges were known on the shores of the European continent (except the British Isles). By 1883 Carlos Ibañez was using information from approximately 67 tide gauge stations for the determination of the mean sea level around the European mainland. Today we find more than 300 installations in Europe, about three-quarters of which are working in north-western European waters and in the Baltic.
Determination of geopotential value W
0
L
at Polish tide gauges from GNSS data and geoid model
