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, Feb 17,

Bridges that Work

Bridges that don’t work Small bridge on a country road is washed away

Most costly urban flood disaster in the history of the United States

Major Highways during Tropical Storm Allison I-45 South I-10 West

Kayaking on US 59, Houston (Tropical Storm Allison)

Residential Flooding in Tropical Storm Allison

The Human Cost Saving the wedding photosCleaning out the car

5-day rain total (Tropical Storm Allison) Harris County City 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 Modeling Program and Master Plan for San Antonio City of San Antonio

Modeling System Rainfall Data: Rain gages Nexrad Calibration Data: Flows Water Quality Geospatial Data: City, County SARA, other Floodplain Management Integrated Regional Water Resources planning Capital Improvement Planning Flood Forecasting Water quality planning San Antonio Regional Watershed Modeling System “Bring the models together”

Nexrad Map to Flood Map in Arc 9 Model Builder FLO ODP LAIN 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 ViewView

Water Supply and Droughts

Streamflow Conditions

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 Sulphur Trinity Nueces City of Austin 8000 water right locations 23 main river basins Inform every permit holder of the degree of reliability of their withdrawal during 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 Basin Water right location Stream gage location Drainage areas delineated from Digital 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 Imane Mrini Center for Research in Water Resources The University of Texas at Austin

Mean = 37µg/L Zinc loads to Nueces Bay Outflow Atmospheric deposition W at = kg/d NPS watershed loadings Q wsh = 1.83 m 3 /s W wsh = 3.69 kg/d Lake Corpus Christi load Q NR = 2.47 m 3 /s W NR = 4.27 kg/d Nueces Bay Permitted discharges Q pd = m 3 /s W pd = 0.71 kg/d CP&L plant W CP&L = kg/d Inner Harbor Average Conc. ( ) = 37µg/L Q = flow of water W = load of zinc

Physicochemical Reactions Sediment-Water Exchange Photochemical Reactions Inorganic Reactions Organic/Biological Reactions Atmospheric Deposition Flux sunlight

Bioconcentration of Zinc Total Zinc in water ( ~ 47  g/L) 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)