Spatial variability of sea level rise due to water impoundment behind dams

Dams have impounded similar to 10,800 km(3) of water since 1900, reducing global sea level by similar to 30.0 mm and decreasing the rate of sea level rise. The load from impounded water depresses the earth's surface near dams and elevates the geoid, which locally increases relative sea level (RSL). We computed patterns of dam-induced RSL change globally, and estimated that tide gauges, which are often close to dams, recorded only similar to 60% of the global average sea level drop due to reservoir building. Thus, RSL in the globally averaged ocean rose similar to 0.2 mm/yr more slowly than has been recorded by tide gauges, or similar to 10% slower than the measured rise rate of 1.5-2.0 mm/yr. Relative proximity to dams caused RSL to rise fastest in northeastern North America and slowest in the Pacific. This dam-induced spatial variability may mask the sea level fingerprint of melting sources, especially northern (Greenland) sources of glacial unloading. Citation: Fiedler, J. W., and C. P. Conrad (2010), Spatial variability of sea level rise due to water impoundment behind dams, Geophys. Res. Lett., 37, L12603, doi:10.1029/2010GL043462.