William B. Hawley1,2, †, Carling C. Hay3, Jerry X. Mitrovica4, and Robert E. Kopp5
1Department of Earth and Planetary Science, University of California, Berkeley, Berkeley, CA 94720, USA.
2Berkeley Seismological Laboratory, 215 McCone Hall, University of California, Berkeley, Berkeley, CA 94720, USA.
3Department of Earth and Environmental Sciences, Boston College, Chestnut Hill, MA 02467, USA.
4Department of Earth and Planetary Sciences, Harvard University, 20 Oxford Street, Cambridge, MA, 02138, USA.
5Department of Earth and Planetary Sciences and Rutgers Institute of Earth, Ocean, and Atmospheric Sciences, Rutgers University, New Brunswick, NJ 08901, USA
Corresponding author: William Hawley (whawley@ldeo.columbia.edu)
Now at Lamont-Doherty Earth Observatory of Columbia University, 61 Rte. 9W, Palisades, NY 10964, USA.
Key Points:
Abstract
The artificial impoundment of water behind dams causes global mean sea level (GMSL) to fall as reservoirs fill, but also generates a local rise in sea level due to the increased mass in the reservoir and the crustal deformation this mass induces. To estimate spatiotemporal fluctuations in sea level due to water impoundment, we use a historical data set that includes 6,329 reservoirs completed between 1900 and 2011, as well as projections of 3,565 reservoirs that are expected to be completed by 2040. The GMSL change associated with the historical data (–0.2 mm yr-1 from 1900 – 2011) is consistent with previous studies, but the temporal and spatial resolution allows for local studies that were not previously possible, revealing that some locations experience a sea level rise of as much as 40 mm over less than a decade. Future construction of reservoirs through ~2040 is projected to cause a GMSL fall whose rate is comparable to that of the last century (–0.3 mm yr-1), but with a geographic distribution that will be distinct from the last century, including a rise in sea level in more coastal areas. The analysis of expected construction shows that significant impoundment near coastal communities in the coming decades could enhance the flooding risk already heightened by global sea level rise.