Thursday, January 12, 2017

So Maybe It's Not Sea Level Rise Drowning Blackwater After All

A few days ago, I blogged about this article about Blackwater Wildlife Refuge "At Blackwater refuge, rising sea levels drown habitat" which was all about how climate change was threatening the site. Today, from the Bay Journal, this article that suggests that maybe the problem is not so much sea level rise as man's previous attempts to manage water in the area: Did acceleration of building ditches dig the grave for Blackwater’s marshes?
From my research, it appears that these ditches were dug in the late 1830s (as demonstrated by county land records as early as 1841 that mention “Cain’s Ditch”). Why would people go to the trouble to dig these ditches if they didn’t stand to bring out a valuable resource such as white oak for shipbuilding or at least cordwood?

Crenshaw looked around at the spongy marsh, seemingly held together only by a few stands of phragmites and water bushes. She asked how they built these canals. Giese  said that “They may have had some sort of dragging dredge, but otherwise they relied on shovels.” Crenshaw looked doubtfully at the mire that is now the marsh. “Of course, the marsh was higher then,” Giese quickly added. “Otherwise, the mud would have slid right back into the ditch.”

I offered my two cents’ worth of history. “We have to rely on other accounts to help tell the story here. The canals in Dismal Swamp in Virginia were dug by enslaved people, who were hired out or able to hire themselves out, a set sum going to the so-called owners and maybe some extra money for the hands to keep for themselves. A story from Quantico in Wicomico County noted that it took seven workers seven years to dig a three-mile canal that was 8 feet deep and 10 feet wide at the bottom.”

The Maryland General Assembly in 1825 used “boilerplate” language for a ditch proposed by John Jaques across Hurley’s Neck to link the Nanticoke and Transquaking rivers south of Vienna—a few miles to the east of here. The authorization states that Jaques “shall cause the dirt coming out of the proposed canal in excavating the same to be thrown equally on both banks or sides of said canal so as to prevent the water from rising and overflowing the marshes and lands through which the said canal shall pass.”
. . .
Did those ditches, along with the cutting down of timber on the edge of the Blackwater marshes, result in erosion and silting? Did these ditches in places sink and/or wash out to create the elongated ponds of the broads?

Did a few ditches we did not visit, those dug to create a shortcut to bypass an oxbow of the river — such as Job’s Ditch down river from Shorter’s Wharf or Raymond Ditch through the oxbow where Meekins Creek once met the Blackwater — help to drown the marsh that was bypassed?

Certainly, the ditches built during the 19th century — notably Stewart’s Canal and the Coursey Creek Canal, both of which connected the upper Blackwater to the Little Choptank River — helped the transformation of the Blackwater basin by opening new stretches to erosion and even another set of tides.
When you're over on the Eastern Shore, particularly when you're out in the marshes, and their's not another soul around, it's easy to imagine that the landscape is pristine. However, our forefather lived on and affected that land in many ways that are not obvious to us now. The truth is, they made a lot of changes, not knowing what the consequences would be (and not really caring; they had to live in their present), and we are seeing many of those consequences now.

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