escoamento superficial: vazão, hidrógrafa, inundações, modelos hidrológicos
TRANSCRIPT
Escoamento Superficial: Vazão, Hidrógrafa, Inundações,
Modelos hidrológicos
• Q - Volume de água passando por um ponto por unidade de área
• Q=VA ou WDV
modified from www.usda.gov/stream_restoration/chap1.htmlFigure 1.18
www.aquatic.uoguelph.ca/rivers/chphys.htm
Vazão e hidrógrafa
Hidrógrafa Anual
www.usda.gov/stream_restoration/chap1.htmlFigure 1.14
Hidrógrafa de evento
Efeitos da urbanização em uma hidrógrafa de evento
http://www.usda.gov/stream_restoration/Images/scrhimage/chap1/fig1-15.jpgFigure 1.15
Caminhos do escoamento superficial
www.usda.gov/stream_restoration/chap1.html Fig. - 2.10
• Ocorrem quando solos – Estão saturados (após pesada chuva)– Possuem baixa permeabilidade (ex. argila)
• Fortemente influenciado pela paisagem e uso da terra– Região de exposição de rochas e base de lagos são
impermeáveis ou tem baixa permeabilidade – Superfícies impermeáveis (estacionamentos) gera
superfícies impermeáveis– Práticas de atividades florestais e agrícolas afetam o fluxo
dos sistemas de drenagem
Escoamento superficial
Características Físicas que Afetam o Escoamento
• Uso da Terra
• Vegetação
• Tipo de Solo
• Área de drenagem
• Forma da bacia
• Altitude
• Declividade
• Topografia
• Direção de orientação
• Padrão de drenagem
• Presença de lagos, reservatórios
• Nós tendemos a ver inundações como eventos não previsíveis e desastrosos. De fato inundações podem ser previsíveis e são ocorrências necessárias.
• Como a superfície impermeável afeta a probabilidade de inundações?
www.aquatic.uoguelph.ca/rivers/chphys.htm
Inundações
• Intervalo de Recorrência– “1 em 100 anos de inundação”– = probabilidade de 0.01 ou 1%– Também referido como intervalo de recorrência– Definido como P = 1 / T, onde:
• P = Probabilidade de Inundação• T = Intervalo de Recorrência
Influência humana sobre as inundações
www.aquatic.uoguelph.ca/rivers/chphys.htm
• Rápido escoamento em rios canalizados aumenta a frequencia de inundações e o pico na hidrógrafa
em pontos a jusante
Menos Superfície Impermeável = Mais Água
Associando Uso da Terra com a Qualidade da Água
Superfície Impermeável
• Fornece uma superfície para acumulação de poluentes
• Leva ao aumento dos poluentes via escoamento e inundação
• Inibe a recarga dos aquíferos
Efeitos Hidrológicos– Ruptura do balanço natural da água– Aumento do pico de inundação– Aumento do escoamento superficial– Maior frequencia de inundações
Impactos das mudanças do uso da terra
www.mmsd.com/stormwaterweb/Volume1B.htm
Escoamento superficial e desenvolvimento
The Importance of Spatial Patterns
Surface hydrologists have recognized the importance of spatial patterns of runoff generation, particularly as driven by topography (e.g. TOPMODEL, SHE, InHM, POWER, ……)
But numerical experiments suggest that even small rates of recharge to deeper layers can dramatically influence patterns of wetness
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ln(a / tanB)
GIS in Water Resources Consortium
Bringing together these two communities by using a common geospatial data model
http://www.crwr.utexas.edu/giswr
GISWater
Resources
CRWR
ArcGIS Hydro Data Model
Hydrography Hydrology
Maidment, 2002
National Hydro Data Programshttp://www.crwr.utexas.edu/giswr/nhdconf/nationalhydro.html
National Elevation Dataset (NED)
National Hydrography Dataset(NHD)
Watershed Boundary DatasetElevation Derivatives for
National Applications (EDNA)
Thematic Layers
supporting the Arc Hydro data model
Michael Zeiler“Modeling Our World”
Streams
Drainage Areas
Hydrography
Channels
Terrain Surfaces
Rainfall Response
Digital Orthophotos
How do we combine these data?
Digital ElevationModels Watersheds Streams Waterbodies
Maidment, 2002
An integrated raster-vector
database
Maidment, 2002
Integrating Data Inventory using a Behavioral Model
Relationships betweenobjects linked by tracing pathof water movement
Maidment, 2002
Intrinsic Hydrologic Modeling
• Dr Tarboton– DEM-based
hydrologic modeling
• USGS– Stream Stats
• Mean annual flows and pollutant loads
http://ststdmamrl.er.usgs.gov/streamstats/expert.htm
Dynamic Linked Library
Can haveFortransubroutinesin a DLL
Muskingumflow routing
Maidment, 2002
Independent Hydrologic Model
VB progam reads and writestext files
Maidment, 2002
Analysis, Modeling,Decision Making
Arc Hydro Geodatabase
Visual Basic
ArcGIS
Relational D
atabase
(Access)
Excel
Interfaces to Arc Hydro Data and Models
Maidment, 2002
Three basic water problems
• Too little water (Drought and water supply)
• Too much water (Flooding)• Its dirty (Water Quality)
Also have significant GIS effort on environmental issues related to water such as habitat assessment
Maidment, 2002
1996 Texas Drought
• George W. Bush, (then Governor of Texas) asked: “Tell me how much water we have, how much water we’re using and how much water we need”
• State water officials did not have adequate answers
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Texas Water Planning
• 1997 Texas Legislature passed Senate Bill 1 which provided for– State-wide geospatial data development
(topography, hydrography, land use, soils and orthophotos)
– Water planning in 14 regions rather than state-wide
– Assessment of water availability for all water permits
Maidment, 2002
Hydrologic Cataloging Units (HUCS)Guadalupe Basin
(4 HUC’s)Hydrologic Unit Code
= 12100203
• 2015 HUC’s cover continental US• average area ~ 1 county Maidment, 2002
Water Availability in the Guadalupe Basin
Stream Gauge (14)
Water Diversion (440)
Estimate water availability at each legally permitted water diversion point based on “naturalized” flow at stream gages and the effects of other permitted diversions
Maidment, 2002
Digital Elevation Model
National Elevation Dataset30m x 30m cells11,000,000 cells to cover San Marcos basin70,000,000 cells to cover Guadalupe basin
San Marcos basin
Maidment, 2002
Drainage Area Delineated from the Digital Elevation Model
Arc Hydro attribute DrainAreaMaidment, 2002
Estimating Naturalized Flow at Diversion Points
Qd
Qf
Ad
Af
Qd = Qf
Ad
Af
Naturalized flow record at stream gage (50 years of monthly flows)
Estimated flow record at diversion point
Maidment, 2002
Length Downstream
D
F
Flow distance (D to F) = Length Downstream (D)
– Length Downstream (F)
Length Downstream (D)
Length Downstream (F)
F
D
Arc Hydro attribute LengthDown
Seepagelosses
Maidment, 2002
Flood Hydrology and Hydraulics
ArcViewInput Data
DEM
HEC-HMSFlood
discharge
HEC-RASWater
surfaceprofiles
ArcViewFlood
plain maps
HEC-GeoHMS Hec-GeoRAS
Maidment, 2002
Stream Definition: Waller Creek
Austin Watersheds with Streamsderived from Aerial Photographs
Streamlines generated by the aerial photographs are not always continuous.
Maidment, 2002
Information for Correcting Stream Network
•DEM
•Contours
•Storm sewers
•Orthophotos
Maidment, 2002
Resulting Corrected Stream
Subsequent steps:• Verification of corrected streams by flood hydrologists.• Running “tracer” program to connect arcs.• Burning of streams into DEM.
Maidment, 2002
Area to Stream Outlet Connectivity
Maidment, 2002
Area to Sewer InletConnectivity
Maidment, 2002
Area to Area Connectivity: SchematicLinks built using
NextDownID
Maidment, 2002
TIWSSTexas Integrated Water Simulation
System
Arc Hydro
Geospatial and Temporal Data
HEC ModelsFlooding & Water Management
ModflowGroundwater
SWATWater Quality
WRAPWater Availability
Maidment, 2002
Flood Plain Mapping
Maidment, 2002
Connecting HMS and RAS
Maidment, 2002
Flood Hydrology and Hydraulics
ArcViewInput Data
DEM
HEC-HMSFlood
discharge
HEC-RASWater
surfaceprofiles
ArcViewFlood
plain maps
HEC-GeoHMS Hec-GeoRAS
Maidment, 2002
HEC-RAS: BackgroundRiver Analysis System model of the U.S. Army Corps of
Engineers
Input = cross-section geometry and flow rates
Output = flood water elevations
Floodway Floodway
Left Bank Station
Flood Water Surface
Right Bank Station
Normal Water Surface
Main Channel
Cross-Section Schematic
Maidment, 2002
Waller Creek
Watersheds ChannelNetwork
Maidment, 2002
Points describe channel and floodway geometry
Bank station locations
Water surface elevations and floodplain boundaries
HEC-RAS: Cross-Section Description
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Discharge at a Particular Cross-Section
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HEC-RAS: OutputText FileGraphical
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Floodplain Mapping: Plan View
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3D Terrain Modeling: Ultimate Goal
Maidment, 2002