The South Atlantic Aquatic Connectivity Assessment project kicked off with a team meeting in Atlanta in January. This project aims to evaluate aquatic connectivity in the SALCC region by assessing barriers, primarily dams, for the potential ecological benefit that would be had by mitigating them through removal or other passage project. The kickoff meeting provided the project team, consisting of members from SARP and The Nature Conservancy’s Eastern Division Conservation Science group, with a chance to all meet in person for the first time, map out a more detailed path through the next 2 years, and start tackling some initial questions.
One key question we wrestled with is which hydrography, or river network in a GIS, to use as the base of the analysis. The hydrography is critical for calculating many of the metrics by which we will evaluate barriers. The hydrography is used in a GIS, for example, to calculate the number of river miles that would be opened by a dam removal. There are several available hydrography datasets available for this use: medium resolution NHDPlus version 1, medium resolution NHDPlus version 2, high resolution NHD, and the high resolution NHDPlus v2 (which doesn’t exist yet). Each of these has advantages and disadvantages and the decision has far reaching implications to the analysis. Not all barriers fall on a given hydrography because in every dataset there are barriers on unmapped waterbodies in that hydrography. A farm pond dam is an example of a case where there could be a mapped barrier in a dam database, but it doesn’t fall on a mapped stream in a given hydrography. Further, barriers that do not fall on the hydrography cannot be included in the project results as it is not possible to calculate many of the metrics for them. (You can’t calculate the number of upstream river miles for a dam in a GIS if the barrier isn’t on a river in your GIS). In the end, we arrived at a compromise solution that attempts to take the best of all worlds. We will use the medium resolution NHDPlus version 2 as our primary hydrography. This allows us to take advantage of the many useful attributes available in the NHDPlus and captures most dams that would be of interest from a connectivity standpoint. We’ll also look at impoundments on smaller streams within the watersheds for each of these dams. This will allow us to say things like “there are 54 small impoundments with a total surface area of 48 acres within the watershed of this dam.” This information, in turn, can be used to inform our understanding of likely flow alteration at that dam. A potential connectivity project might be less attractive if the stream flow is likely to be significantly altered by many small upstream impoundments.
Beyond the hydrography question, we are working to assemble a project Workgroup which will help guide the project, assist with data acquisition/review, and review interim results. The Workgroup will have regular web-based meetings (likely every month or two) over the course of the project. We have identified several potential members and will be contacting folks over the next week or two. If you’re interested in joining – in any capacity – send me an email.
Finally, after much debate we came up with the all-important project acronym. Putting a slight twist on the project name we are now SEACAP – the Southeast Aquatic Connectivity Assessment Project.
For more info, see our SALCC_FactSheet.pdf.