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[Music playing]


Faith: Joe, what's a baseflow channel?

Joe:The Howards Branch project was this


U- shaped incised channel, which is very


common in stormwater dominated systems.


It's a result of urbanization. A really


common approach to stream restoration is


natural channel design, which uses that


full U-shaped channel and develops a


bankfull channel inside of that. And in


these systems where we have very little


sediment supply from the watershed, a


really very disturbed hydrologic regime


that's stormwater dominated, that approach


doesn't seem to be working very well.


The idea of designing this big channel


that for the most of the year has very


little water in it – the only time it's


full of water is when we have a stormwater


runoff event – is not as purposeful from


extracting some of the goods and services


that ecosystems deliver as this kind of a


channel, which is a baseflow channel.


The idea here is you design this shallow,


broad system so that when you do have


those stormwater events, instead of the


water getting deep, which increases sheer


stresses and the ability of that channel


to erode the bottom of the stream and


cause channel enlargement – instead of


going that route, you have this parabolic


weir that when you have any increase in


stage instead of having an increase in


depth, you build width.


This weir that we're looking at here is 40


feet wide, but over time it's grown in, so


only this active flow path is showing. So


this is bankfull, where baseflow is the


only water that fits in there. Any


additional water is out on the adjacent


floodplain or in the riparian zone. And


that serves to reduce the erosive


velocities, it really maximizes the


surface area of the water with the natural


system – the floodplain – which results in


improved sediment trapping, nutrient


removal, more habitat, basically all those


ecosystem services that we're looking for.


Faith: So kind of maximizing the effects


that you can get from the floodplain and


the connection between the floodplain and


the channel.


Joe: Right. We're trying to design a


channel that provides material processing


rather than material conveyance. This


storm-water is a water resource and the


sooner we start designing those projects


with the utility of that water, the sooner


we're on the right path. And that goes to


the idea of the sand seepage wetlands as


well. If we have a pulse of stormwater


coming in here, in some cases you don't


have a big floodplain that you can get the


water out onto. So then you can sort of


ecologically engineer a different


approach, which is to get that pulse of


water and store it on the side of the


floodplain in a pool that's rimmed with


this layer of sand.


Over time, that water has to get back into


the stream and it has to go through that


sand bed to do it and it delivers all the


values that we recognize with a lot of


other stormwater BMPs, whether they're


bioretention facilities, sand filters,


etc. So it's another way to think about


ecological engineering in a riparian


system.


Faith: Taking advantage of what the


vegetation has to offer you.


Joe: Right.


[Music playing]

[End of Audio]

Title: Recreating baseflow channels, Howards Branch, Baltimore, Maryland

Description:

Faith Fitzpatrick (U.S. Geological Survey) and Joe Berg (BioHabitats, Inc.) describe base-flow channels and sand seepage wetlands in a wetland complex at an old millpond setting along a highly urban section of Howards Branch. Recreated baseflow channels enhance changes in width with increased stormwater flow. These channels maximize the effectiveness of floodplain vegetation and nutrient/sediment uptake.

Location: Baltimore, MD, Howards Branch, USA

Date Taken: 7/20/2011

Length: 3:52

Video Producer: Douglas A. Harned , National Water-Quality Assessment Program (NAWQA), USGS, North Carolina Water Science Center, Raleigh, NC

Note: This video has been released into the public domain by the U.S. Geological Survey for use in its entirety. Some videos may contain pieces of copyrighted material. If you wish to use a portion of the video for any purpose, other than for resharing/reposting the video in its entirety, please contact the Video Producer/Videographer listed with this video. Please refer to the USGS Copyright section for how to credit this video.

Additional Video Credits:

Faith Fitzpatrick: Scriptwriter, Narrator, Scientist Consultant

Gerard McMahon: Producer

Douglas Harned: Producer, Video, Editor

Alan Cressler: Video

Luke Myers: Video

Joe Berg (BioHabitats, Inc.)

File Details:

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• W3C Timed-Text captions file
• YouTube version *
• Text transcript

Suggest an update to the information/tags?

Tags: AquaticEcology BaseFlow BiohabitatsInc DouglasHarned EUSE Ecosystems FaithFitzpatrick Floodplain Habitat HowardsBranch Hydrology Maryland NAWQA StreamRehabilitation StreamRestoration USGS Urbanization WaterQuality WaterResourceManagement Wetlands