A Crab’s Eye View Of Rising Tides In A Changing World
Coastal ecosystems and aquifers will be greatly affected by climate change, not only from rising temperatures and more volatile weather, including changes in precipitation patterns, but also from sea level rise.
(From Science Daily)– In the search for methods to analyze these effects, researchers at NJIT have identified powerful statistical tools that should help coastal scientists both measure and anticipate changes in conditions such as subsurface water temperature and salinity. Results from the study, funded by the National Oceanic and Atmospheric Administration, have been published in Scientific Reports, an online affiliate of Nature.
The tools, known as spectral and co-spectral techniques, required a large data set for validation, which the authors obtained from two beaches in Prince William Sound in Alaska. In particular, they looked at the impact of sea level variability on these beaches, collecting a year’s worth of data on water pressure, water temperature and salinity at thirty-minute intervals from sensors embedded in the sand.
Using these techniques to identify trends within the data, they found that at most locations, the effects of sea level rise were first seen in the water pressure in aquifers, followed by changes in salinity and then temperature. Following in the wake of the other two leading indicators, or warning signals, it appears that changes in temperature would take longer to be felt inland than rising salinity.
“Changes in the temperature were sometimes seen a week later than both rising water pressure and salinity. We attribute this to soil grains acting as a thermal buffer, absorbing a non-negligible fraction of the heat carried by seawater and fresh groundwater. Thus, even if the sea temperature should change suddenly, it would take a week or more for its effects on coastal aquifers to subside,” said Michel Boufadel, director of NJIT’s Center for Natural Resources Development and Protection (NRDP), a professor of environmental engineering and an author of the study.
Water pressure was the first to change as water is incompressible and thus transmits pressure rapidly. Rising salinity, by comparison, is mitigated by the spreading and dilution of seawater when it interacts with fresh groundwater coming from the upland behind the beach.
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