A Study of concurrent rainfall-runoff in austin, tx

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A Study of concurrent rainfall-runoff in austin,
tx

• rose marie klee

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problem

• Tailwater assumptions
• Magnitude of concurrent events
• Waller Creek Tunnel Project

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problem
Tailwater Elevation
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problem
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problem
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problem
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Background

• Available guidance
• Waller Creek and Colorado River basins
• Areal Reduction Factors

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background
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background
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background
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methodology

• Obtained Colorado River HMS model from LCRA
• Computed ARFs
• Used GIS to create/compute circular storm and
  calculate an aggregate ARF for each subbasin
• Used HMS to model multiple storms in the Colorado
  River Basin
• Evaluated results

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methodology
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methodology
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methodology
area (mi2) radius (mi) ARF - Asquith99
1 0.6 0.947
10 1.8 0.894
30 3.1 0.786
50 4.0 0.761
75 4.9 0.741
100 5.6 0.728
150 6.9 0.708
225 8.5 0.688
300 9.8 0.671
450 12.0 0.647
675 14.7 0.621
1000 17.8 0.593
1500 21.9 0.560
2250 26.8 0.524
3000 30.9 0.495
4000 35.7 0.463
5000 39.9 0.438
6000 43.7 0.418
7000 47.2 0.403
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methodology
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methodology
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results
hydrologic element drainage area (mi2) time of peak (hhmm)
AL-27 28.62 1405
    peak discharge (cfs) volume (in) volume (ac-ft)
100-yr SCS storm over all basins 100-yr SCS storm over all basins 23,602 7.51 11,467
no ARFs over select basins no ARFs over select basins 23,488 7.50 11,450
ARFs over select basins ARFs over select basins 18,711 5.84 8,908
change in change in change in change in change in
peak discharge (cfs) peak discharge () volume (in) volume (ac-ft) volume ()
4,778 20.3 1.66 2,542 22.2
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results
    peak discharge (cfs) volume (in) volume (ac-ft) change in change in change in
    peak discharge (cfs) volume (in) volume (ac-ft) peak discharge (cfs) volume (in) volume (ac-ft)
no ARFs over select basins avg 37,697 1.263 28,619 26,023 0.729 18,415
ARFs over select basins avg 11,673 0.535 10,204 26,023 0.729 18,415
no ARFs over select basins max 620,040 8.930 637,221 456,334 5.720 395,434
ARFs over select basins max 163,706 5.840 241,787 456,334 5.720 395,434
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results
hydrologic element drainage area (mi2) time of peak (hhmm)
AL-27 28.62 1405
event peak discharge (cfs) volume (in) volume (ac-ft)
100-yr (no ARF) 23,488 7.50 11,450
100-yr (w/ARF) 18,710 5.84 8,908
50-yr (no ARF) 20,142 6.33 9,663
25-yr (no ARF) 17,055 5.27 8,044
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conclusions

• Not the whole storystorms move hydrograph
  timing is important.
• Further work could include elliptical storms,
  different reduction factors, moving storms,
  inclusion of hydraulic model, analysis of real
  storms.