Stream Restoration Asset Mapping

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1 Stream Restoration Asset Mapping John Dean Amy Bergbreiter March 27, 2014 Georgia Association of Floodplain Management Conference Hyatt Regency, Atlanta, GA

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4 Sediment comes mostly from stream banks, not impervious surface. As a reaction to this, we have tried to stabilize our stream banks.

5 Watershed Improvement Projects We will end up with a lot more!

6 We want to track our expenditures and the value of our work. This is called asset management.

7 Stream restoration is a big part of this. Sapelo Trail Stream Restoration Site

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9 Stream Work-Grading

10 In some cases, we create a new channel. Stream bank protection Structures Relocated Channel

11 This presents data-model problem #1. Streams continuously change their design characteristics along length. How do we negotiate this?

12 Realization: We didn t need to capture how the design varies. We store the cost holistically. Doesn t really matter how the design ebbs and flows. Don t need to treat changes as discrete assets. The whole thing is (debatably) an asset. Therefore: You don t need linear referencing. lessons learned were that we did not want to bother with linear referencing (theoretically elegant, but not practical). Guiding Principle: Need assets, not design.

13 We do want to inventory individual structures because they are discrete assets.

14 Stream Work-Structure Installation

15 Bank protection is captured by tracing the stream centerline Can use symbology to offset line to show left vs. right bank

16 Categorization is a necessary evil of geographic databases. In cartography, it is called simplification.

17 This presents data-model problem #2. How do you sort a spectrum of customized solutions into boxes?

18 Realization: You can broaden your categories with subfields. Example: Step pools We built enough flexibility into our cross vane category that we could capture step pools as a series of cross-vane types. Example: Amphitheater We had a loosely qualified category bench that could accommodate our amphitheater. Solution: Make your bins big and flexible so as to cast a wide net. Guiding Principle: When in doubt, put a feature in a category with other features that have similar replacement costs or require similar types of equipment. Think asset not hydrology.

19 Instead of only these categories of vanes, the categories can be further qualified with additional characteristics.

20 Instead of just a bridge or a retaining wall, a plethora of other qualification are available to further qualify these structures to accommodate customizations.

21 Solution: We installed a series of boulders to create an amphitheater at McDaniel Farm represented it with a series of benches

22 Next consideration: Most organizations have regular feature classes for their conventional inventory.

23 This presents data-model problem #3. Some of your restoration structure resembles conventional inventory. Bioretention outlets Stream restoration reaches

24 First realization: We do not want to duplicate data. Example: Bioretention outlets We decided to use the conventional yard inlet inventory for holding these features. Second realization: We are going to have to duplicate some data. Example: Stream restoration reaches We have non-conduits in our inventory, but we couldn t use them. We fell back on a duplicated GIS layer. Solution: Use as much of your existing data model as possible, but if you have to, make your own. Conflate the duplicated layers so both are as accurate as possible. Tip: When mapping a stream restoration project, expect considerable mapping in your conventional stormwater inventory, too.

25 It s actually a customized solution, but we call it a conventional yard inlet. Tip: You don t want to proliferate on your feature classes.

26 SUMMARY Time spent planning, sometimes changing plans. Building the data model. Populating your database. Technology Capital: Little new cost. We already had it. Human Capital: Expect to use your talent. Expect to use your people. Budget for ample hours. We recommend assigning the task to a small team. A field person An engineer A GIS database person Tip: You will want to prearrange for surveyors to provide as-built drawings. You will want these in CAD format as well as.pdf.

27 BENEFITS Together with all your other layers IMMEASURABLE. Linked to an asset management/work order database EVEN MORE POWERFUL. You can track where you re spending your money and assign work orders. You should do this! There is no substitute for having GIS and asset management layer. Plans, CAD files, and maps are no substitute. GIS is a unifying technology, works best by combining and overlaying. Potentially more valuable as structures age, institutional knowledge fades, and you get more GIS layers. Put it on your publicly facing web maps!

28 Using a digital elevation model (DEM),we can map the area contributing to any pour point.

29 This allows us to map the catchments and impervious contributions for any tributary.

30 FUTURE RESEARCH Quantify the return on investment (ROI). Is linear referencing practical or impractical? Take what we have done and adapt it to your situation! John Dean Amy Bergbreiter Gwinnett County Department of Water Resources Stormwater Management Division Lawrenceville, Georgia USA.

31 Questions? John Dean, GISP Amy Bergbreiter, P.E. Gwinnett County Department of Water Resources

32 THE END Slides after are available, if needed;

33 Representations offer us a stable, flexible platform to store our cartography. You can personally draw and modify these renderings and make them very artistic, morphological and intuitive. They travel with the database and make the data more valuable.

34 We store our symbols as Cartographic Representations. This means they do not have to be in any style file. Arcmap 10.x -values in a knows how draw these symbols directly from geodatabase.

35 Pictures During a Rain Event

36 Cross vanes, a diversion structure, a foot bridge, and a conventional conduit.

37 Using a DEM from LIDAR data we map the catchments that flow into pour points.

38 ArcMap and ArcTools calculate how the stream concentrates...

39 ... but it is important to precondition the DEM.

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44 Gwinnett County, GA A spacious, suburban county of about 800,000 people located in the southeast U.S. 40 miles northeast of Atlanta, GA.

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