1. Hydrotechnical Design Guidelines for Stream Crossings
Alberta Infrastructure and Transportation

2. Design Parameters Require Y, V, Q Typical large runoff response
Consistent with Physics, History
Optimize crossing design
Require : Y – superstructure above HW, V – design of protection works, Q – constriction, comparison
Water Management – volume, timing (hydrograph)
Typical : rainfall (150 – 200mm rainfall with Tp = 15 – 30hrs), snowmelt (d = 35 – 45mm, Tp = 40hrs), no frequency
Water Management – more extreme for High & Large Dams
Physics : channel capacity, contributing DA ; History – site, region – HWM, maintenance, rehabilitation
Water Management – flood control operation
Optimize : baseline boundary conditions apply to site, opening design may vary risk depending on importance - constriction, freeboard…
Water Management – no net impact, spillway + aux. split

3. Approach 1. Channel Capacity 2. Historic Observations
3. Basin Runoff Potential
Capacity – hydraulic calculation of flow that activates significant storage, implicit routing
Water Management – still applicable for inflows
History – HW data from files, WSC data (Q, stage), Storm database
Water management – dam operation
Runoff – unit discharge (runoff depth map) x contributing DA – upper bound
Water management – hydrograph shaping

4. 1. Channel Capacity Define typical channel parameters : B, T, h, S
Assign stage :
Calculate V, Q – AT, Manning equation
Governs – most sites with overbank storage h Y
< 1.0m
h + 0.5m
1.0 – 2.0m
1.5 * h
> 2.0m
h + 1.0m
Typical – field measurements, photos, survey, drawings, airphotos, satellite photos ; DTM for slope ; note man-made changes, bridge scour
B – bed width, T – top of bank width, h – bank height, S – channel slope
Stage – study of observed historic floods on drawings – very few > 1m over h, most BW due to bridge + flood storage activation, modification to response
AT equation – 14R^0.67S^0.4, based on WSC measurements + DTM slope estimates, for B > 10m.
Water Management – extension of rating curve for more extreme events

5. 2. Historic Observations
HW data from bridge files, database
WSC Data – Q, Y for peak events
Storm Database – ID likely response
Governs – large rivers
HW – HW inspection, AENV ; HWM - bridge reports, BIM, local interviews, photos, airphotos, newspaper clipping, maintenance history
HW – note - headloss, debris/drift blockage, extent of flooding, scour erosion, V
WSC – published Q, rating curve to Y, actual gauging.
Storm – 139 historic storms, overlap basin, calc r, if > 100mm likely response.

6. 3. Basin Runoff Potential
Qp = q x A (upper bound)
q - runoff depth map (cms/km2)
A – contributing
Storage routing
Governs – small basins, steep channels
Qp – upper bound for Q based on runoff potential for area
q – calculate from d, Tp from runoff depth map
A – exclude areas with peripheral lakes, marsh, no drainage network
Routing – d/s of large lake ; rough – assumptions
Water management – shape runoff hydrographs (volume, timing)

7. Compile Hydrotechnical Summary
Concise summary
Summarizes all 3 components
Conclusion : Y, V, Q
Consider u/s and d/s sites (HIS)
Concise – 1 page
Summary – brief section summarizing each of 3 techniques
Conclusion – which governs, Y,V,Q to use
U/s and d/s – consistent results along stream, consider more data

8. Tools HIS PeakFlow Storm On Basin Global Mapper
Calculation – hydraulics, routing
HIS – stream link, flood database, slope, file history, hydrotech summaries
PeakFlow – WSC Data, query, peak Q, hydrographs, rating curves, gaugings
Storm on Basin – 139 storm db, overlap calculation, graphics
Global Mapper – contributing DA, S, satellite photos, DTM
Hydraulics – HydroCulv, Flow Constrict, Channel Capacity Calculator