Week of April 9, 2023 – April 15, 2023
by David DuBois, Land Steward
Water, even on small streams can create impressive changes. Just this past Wednesday rain flooded Spring Brook here at Baltimore Woods, and washed out a culvert on the Boundary Trail. This water moved cubic yards of material in short order and destroyed a section of trail, certainly a force to be reckoned with. Fortunately the hard work of dedicated volunteers got this stretch of trail opened again within a few hours.
The destructive nature of these floods is only one side of streams in flood, however. The high water allows the creek to find new channels and carve new routes. These channel alterations create oxbow ponds and wetlands, increasing the diversity of habitats on the floodplain. Just downstream of the Lower Valley Trail bridge across Baltimore Brook is a spot with channel change in progress. The creek is cutting a new channel and forming what will soon become a new oxbow wetland. Look for these developing features on Griffith’s Trail, Boundary Trail, Harrison trail, or wherever the brooks are visible. Try to imagine how the creek will look in its new bank, and what changes that will create on the floodplain.
The high water also transports nutrient rich sediment with it, building up the floodplain and fertilizing the plants growing there. These floods also scour, creating bare patches for floodplain trees and herbs to germinate. Look for sediments on and around the Griffith Trail to appreciate just how much material moved in this flood.
This dynamic process of stream change is constantly in flux creating and modifying habitat that species depend on. This creates habitat complexity both spatially and temporally and makes the floodplain an incredibly diverse habitat.