when did the sea level start to rise
Sea level rise Various factors affect the volume or mass of the ocean, leading to long-term changes in eustatic sea level. The two primary influences are temperature (because the density of water depends on temperature), and the mass of water locked up on land and sea as fresh water in rivers, lakes, glaciers and polar ice caps. Over much longer geological timescales, changes in the shape of oceanic basins and in landâ€“sea distribution affect sea level. Since the Last Glacial Maximum about 20,000 years ago, sea level has risen by more than 125 m, with rates varying from tenths of a mm/yr to 10+mm/year, as a result of melting of major ice sheets.[15]
Lake Powell Upon completion of Glen Canyon Dam on September 13, 1963, the Colorado River began to back up, no longer being diverted through the tunnels. The newly flooded Glen Canyon formed Lake Powell. It took 11 years for the lake to fill to the 3,700 feet (1,100 m) level, on June 22, 1980. The lake level fluctuates considerably depending on the seasonal snow runoff from the Rocky Mountains.[4][5][6] The all-time highest water level was reached on July 14, 1983, during one of the heaviest Colorado River floods in recorded history, in part influenced by a strong El Niño event. The lake rose to 3,708.34 feet (1,130.30 m) above sea level, with a water content of 25,757,086 acre feet (31.770898 km3).[7]