Presentation on theme: "Tracking Lateral Stream Instability with Geo- Referencing Tools By Lana Potapova, E.I.T. www.inftra.gov.ab.ca."— Presentation transcript:
Tracking Lateral Stream Instability with Geo- Referencing Tools By Lana Potapova, E.I.T. www.inftra.gov.ab.ca
What is lateral stream instability and why is it important to track it?
Why is tracking lateral stream instability important? River moved laterally and washed out 50m of fill BF75904: HWY 33 over Island Creek
Why is tracking lateral stream instability important? Drift block at the bridge causes the water to take another path
Why is tracking lateral stream instability important? The river moved too close to the road as can be seen by the bank erosion
Why is tracking lateral stream instability important? This bridge is on poor alignment which causes many problems BF78104: HWY 32 over McLeod River
Why is tracking lateral stream instability important? Poor alignment causes head- slope erosion Local Road over Marten Creek
Why is tracking lateral stream instability important? Incorrect skew leads to drift accumulation at pier
Why is tracking lateral stream instability important? Incorrect skew leads to pier scour BF 74710: HWY 40 over Berland River
How can lateral stream instability be tracked? Comparison of historic aerial photographs, satellite imagery, scour survey data, etc. All these sets of data are to a different scale and comparing them side by side is hard Put some satelite pics here
What is Global Mapper Geo-Referencing? GIS software Allows to compare digitized layers (aerial photos, surveyed data)
2006 Satellite Image used as base layer because it is orthorectified (corrected for topography and angle of shooting)
Case Study: Little Red Deer River Originally worried about a low spot in the road and the channel cutting off through the flood plain No significant movement, so it’s low risk that the channel relocates but we’re still monitoring it Discovered that the south bank upstream of the bridge is eroding The bridge is new, so it matched the bank and right now it’s not at a risk – however, we are keeping an eye on it in the future Currently it is monitored
Case Study: Freeman River AIT was approached by Alberta Environment with concerns about bank erosion in the vicinity of the bridge
Case Study: Drayton Valley Geo-referencing allowed visualize flood extents and flow profile Geo-referencing Also showed that channel might be migrating and the spur can lose its function and that upstream alignment alternative are unfavorable from a river engineering perspective
Final Words on Geo-Referencing Not a substitute tool for any one feature; simply provides added value (i.e. we still use paper aerial photos with a stereopair to visualize things in 3-D) Final images provide documented evidence as a justification for spending money or choosing a certain design alternative This tool can be used for maintenance recommendations or as documentation during Level II BIM inspections of the channel Also useful during planning phase (Drayton Valley) If we’re providing input into functional planning, we’re hoping to use this tool to identify the least volatile region of the river for a potential crossing.
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