Map-Based Flood Hydrology and Hydraulics David R. Maidment Jan 10, 1998.
Water Resources Engineering by David R. Maidment
description
Transcript of Water Resources Engineering by David R. Maidment
Water Resources Engineering
by David R. Maidment
• The challenges – floods, droughts, poor water quality
• What we are doing about them– engineering structures, better planning,
management• What we study
– Academic Program at UT
Flooding Manawatu, New Zealand
http://www.ourregion.co.nz/home.php
Bridges that Work
http://www.ourregion.co.nz/home.php
Bridges that don’t work
http://www.ourregion.co.nz/home.php
Small bridge on a country road is washed away
http://www.tsarp.com/
Most costly urban flood disaster in the history of the United States
Major Highways during Tropical Storm Allison
I-45 SouthI-10 West
http://www.chron.com/content/chronicle/special/01/flood/
Kayaking on US 59, Houston(Tropical Storm Allison)
http://www.chron.com/content/chronicle/special/01/flood/
Residential Flooding in Tropical Storm Allison
http://www.chron.com/content/chronicle/special/01/flood/
The Human Cost
Saving the wedding photos Cleaning out the car
http://www.chron.com/content/chronicle/special/01/flood/
5-day rain total (Tropical Storm Allison)
Harris CountyCity of Houston
12-hour rain total (Tropical Storm Allison)
Extreme Rainfall Statistics (Tropical Storm Allison)
73,000 houses and apartment buildings flooded
Watersheds
Watershed = area that drains to a particular river or stream network
Stream gaging station
Floodplain maps(White Oak Bayou, Houston)
What can we do about floods?
• Engineering structures– Dams and detention ponds to hold back flood
waters– Increase capacity of streams to carry floods
• Better flood planning– Create floodplain maps to define at-risk areas– Restrict building foundations are at least 1 foot
above 100-year flood elevation– Develop flood forecasting and warning systems
Regional Storm Water Regional Storm Water Modeling Program and Modeling Program and
Master Plan for San Master Plan for San AntonioAntonio
City ofSan Antonio
Modeling System
Rainfall Data:Rain gagesNexrad
Calibration Data:FlowsWater Quality
Geospatial Data:City, CountySARA, other
FloodplainManagement
IntegratedRegional Water
Resources planning
CapitalImprovemen
tPlanning
FloodForecasting
Water qualityplanning
San Antonio Regional Watershed Modeling System
“Bring the models together”
Nexrad Map to Flood Map in Arc 9 Model Builder FLO
ODPLAIN MAP
Flood map as output
Model for flood flow
Model for flood
depth
HMS
Nexrad rainfall map as input
3D Terrain Modeling
Floodplain Mapping: 3-D View
Water Supply and Droughts
http://agnews.tamu.edu/drought/pics.html
http://agnews.tamu.edu/graphics/drought98/TXrainAprJun98BG.html
Streamflow Conditions
http://tx.waterdata.usgs.gov/nwis/rt
What can we do about droughts and water supply issues?
• Water resource development– Reservoirs and well fields to supply water
• Better water resources planning– Senate Bill 1 (1997 Legislature) established 14
water planning regions in Texas– Water Availability Modeling– Drought forecasting (El Nino – Southern
Oscillation)
Improvements from Senate Bill 1:Water Modeling and Planning
• Before Senate Bill 1, water planning was done state-wide by TWDB
• SB1 established 14 water planning regional groups, who are now responsible for planning water supply in their area
Water Availability Modeling (TNRCC)
Improvements from Senate Bill 1: Water Availability Modeling
Rio Grande
Colorado
Brazos SulphurTrinity
Nueces
City of Austin
8000 water right
locations
23 main river basins
Inform every permit holder of thedegree of reliability of their withdrawalduring drought conditions (TCEQ)
CRWR Mission for Senate Bill 1
• CRWR (UT Austin) aids in the response to Senate Bill 1 by providing to TCEQ watershed parameters defined from geospatial data for each water right location
• These data are input by TCEQ contractors to a Water Rights Assessment Package (developed at TAMU) which determines the % chance that the water will actually be available at that location
• TCEQ sends the owner of the water right a letter specifying the availability of water
Water Rights in the Sulphur BasinWater right locationStream gage location
Drainage areas delineated fromDigital Elevation Models are used to estimate flow at water right locations based on flow at stream gage locations
Water Quality
Background of Clean Water Act• 1972 Clean Water Act prohibits any
discharge of pollutants without NPDES permit - (fishable and swimmable)
• 1987 Clean Water Act amended to require NPDES permits for stormwater discharges
• Permits require implementation of Best Management Practices (BMPs) to reduce pollutant discharges to “Maximum Extent Practicable”
Location of Impaired Waters
Austin Area Impaired Water Segments
• Bull Creek – Impaired macrobenthic community• Onion Creek – Depressed dissolved oxygen• Slaughter Creek – Impaired macrobenthic community• Waller Creek – Impaired macrobenthic community• Eanes Creek – Bacteria • Gilleland Creek – Bacteria• Taylor Slough – Bacteria• Spicewood Creek - Bacteria
What can we do about water quality?
• Water quality enhancement structures– Sand filters, wet ponds– Screening inlets to storm sewers
• Total maximum daily load (TMDL)– Comes from Clean Water Act– Pollution load that a water body can accept and
still maintain its beneficial uses (aquatic life support, recreation, water supply)
Requirements for Structural Best Management Practices (BMP’s)
• City of Austin – Required since 1981, mainly sand filters
• TCEQ – Requires removal of 80% of sediment in stormwater for Edwards Aquifer
• LCRA – Requires 70-75% removal of sediment, phosphorus, and oil & grease for Highland Lakes
TxDOT Sand Filter
Central Park Wet Pond (Austin)
Extended Detention Basin
Nueces Bay Zinc in Oyster Tissue TMDL Project
Corpus Christi
3,000Meters
Imane Mrini
Center for Research in Water Resources
The University of Texas at Austin
Total zinc in water-Inner Harbor
0.0
10.0
20.0
30.0
40.0
50.0
60.0
70.0
12/1/80 8/28/83 5/24/86 2/17/89 11/14/91
8/10/94 5/6/97 1/31/00
Date
Con
c (µ
g/L)
13430 13429 13432 13439
Mean = 37µg/L
Zinc loads to Nueces Bay
Outflow
Atmospheric deposition Wat = 18.67 kg/dNPS watershed loadings
Qwsh = 1.83 m3/sWwsh = 3.69 kg/d
Lake Corpus Christi loadQNR = 2.47 m3/sWNR = 4.27 kg/d
Nueces Bay
Permitted dischargesQpd = 16.55 m3/sWpd = 0.71 kg/d CP&L plant
WCP&L = 52.75 kg/d
Inner Harbor
Average Conc. (1982-2001) = 37µg/L
Q = flow of waterW = load of zinc
Physicochemical Reactions
Sediment-Water Exchange
Photochemical Reactions Inorganic Reactions
Organic/Biological Reactions
Atmospheric Deposition
Flux Flux
sunlight
Bioconcentration of Zinc
Total Zinc in water( ~ 47 g/L) 0.047 ppm
Zinc in sediment( ~ 100 mg/kg)
100 ppm
Zinc in Oyster tissue(~ 1100 mg/kg)
1100 ppm
Ratio = 23,400
Ratio = 11
Ratio = 2127
Academic Program at UT
• Required courses– CE 319F Elementary Fluid Mechanics – CE 356 Hydraulics
• Electives– CE 358 Ocean Engineering– CE 370K Water Chemistry – CE 374K Hydrology – CE 365K Hydraulic Design (Level II)
CE Faculty in Water Resources
• Randall Charbeneau (groundwater, hydraulic design
• Ben Hodges (hydraulics, hydrodynamics)• Lynn Katz (water chemistry)• Spyros Kinnas (fluid mechanics, ocean
engineering)• Daene McKinney (water resources planning)• David Maidment (hydrology, geographic
information systems)