Sea level rise has become an increasing problem for the Chesapeake Bay region. But, added to climate change there is also the land subsidence of the area itself. In our weekly series with the Bay Journal Delmarva Public Media's Don Rush talks with reporter Jeremy Cox about the latest study and its results.
RUSH: The Chesapeake Bay region is sinking. This is Don Rush. It's known as land subsidence, but now in some places it accounts for more than half of the sea level rise in parts of the bay. In our weekly series with Bay Journal, we talk with reporter Jeremy Cox. What researchers have found in their latest study:
COX: Relative sea level rise is more pronounced around the Chesapeake Bay region because not only are the seas rising, but also the lands you say is sinking. And mostly that has to do with the fact that the glacier has moved away to the north of us and the earth's crust is settling back down, but also in a lot of areas you have groundwater pumping.
RUSH: So what did they find in terms of, say, the northern portion of the bay, I suppose, to the southern portion of the bay?
COX: So the northern part, the part closer to where the glaciers were, was a little bit slower. So places around the Susquehanna River, the upper shore, that sort of area, while the southern part of the bay was a little bit faster. And we're talking the difference of maybe one millimeter per year that makes a difference on the timescales that we're talking about here.
RUSH: Now, in terms by the way of the Delmarva Peninsula, what are we looking at there when it comes to say Cambridge or Salisbury, even the central Delaware.
COX: This area appears to be speeding up in terms of the shrinkage that you talked about going back many years, we've known that the Hampton Roads area down by Norfolk is kind of the epicenter of sinking because it has a lot more groundwater pumping going on. But it looks like from this study that central Delmarva is caught up with them and the study doesn't really state why it probably has to do something with more groundwater pumping around here. But that's going to take further study to really explicate that.
RUSH: These studies, how do they differ from, say for instance studies that say use say radar?
COX: This study has used actually the technology that I'm holding in my hand right now, A GPS, so satellites bouncing a signal back down to Earth and you get these really hyper precise, less than a millimeter differences, especially when you repeat the study over and over again each year as they did the same locations, you're able to really get a good triangulation with it there. So the previous studies also use different methods, radar, or maybe if they did use GPS or if they did look at the Bay Region, maybe they were just looking at this corner of the Bay Region. And this gives a really good baseline.
RUSH: Just in terms of growth itself, given the fact that we've now seen more growth than we have in the past. I'm assuming we'll see more groundwater being pulled out. And the assumption is therefore we should perhaps see even greater amounts of subsidence if indeed this is connected.
COX: Right, and I think that's why they wanted to undertake this study because policymakers can get out ahead of those issues. Large groundwater withdrawals need to have in both states, Maryland and Virginia state permits to be able to do that. And perhaps knowing that those groundwater withdrawals could further exacerbate this issue of land sinking could cause those policymakers to make different decisions, maybe to restrict this kind of pumping or in certain areas to restrict certain types of operations or population growth out of those kinds of concerns.
RUSH: Bay internal reporter, Jeremy Cox on the land subsidence that is contributing to sea level rise in the Chesapeake Bay region. This is Don Rush for Delmarva Public Media.
