Post on 04-Jan-2016
A STUDY OF CONCURRENT RAINFALL-RUNOFF IN AUSTIN, TX
rose marie klee
problem
Tailwater assumptions Magnitude of concurrent events Waller Creek Tunnel Project
problem
Tailwater Elevation
problem
problem
problem
Background
Available guidance Waller Creek and Colorado River basins Areal Reduction Factors
background
background
background
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
methodology
methodology
methodology
area (mi2) radius (mi) ARF - Asquith991 0.6 0.947
10 1.8 0.89430 3.1 0.78650 4.0 0.76175 4.9 0.741
100 5.6 0.728150 6.9 0.708225 8.5 0.688300 9.8 0.671450 12.0 0.647675 14.7 0.621
1000 17.8 0.5931500 21.9 0.5602250 26.8 0.5243000 30.9 0.4954000 35.7 0.4635000 39.9 0.4386000 43.7 0.4187000 47.2 0.403
methodology
methodology
results
hydrologic element
drainage area (mi2)
time of peak
(hh:mm)
AL-27 28.62 14:05
peak discharge
(cfs)volume
(in)volume (ac-ft)
100-yr SCS storm over all basins 23,602 7.51 11,467no ARFs over select basins 23,488 7.50 11,450
ARFs over select basins 18,711 5.84 8,908
change in:peak
discharge (cfs)
peak discharge
(%)
volume (in)
volume (ac-ft)
volume (%)
4,778 20.3% 1.66 2,542 22.2%
results
peak
discharge (cfs)
volume (in)
volume (ac-ft)
change in:peak
discharge (cfs)
volume (in)
volume (ac-ft)
no ARFs over select basins avg 37,697 1.263 28,619 26,023 0.729 18,415ARFs over select basins 11,673 0.535 10,204no ARFs over select basins max 620,040 8.930 637,221 456,334 5.720 395,434ARFs over select basins 163,706 5.840 241,787
results
eventpeak
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
hydrologic element
drainage area (mi2)
time of peak
(hh:mm)
AL-27 28.62 14:05
conclusions
Not the whole story…storms move; hydrograph timing is important.
Further work could include: elliptical storms, different reduction factors, moving storms, inclusion of hydraulic model, analysis of real storms.