Escoamento Superficial: Vazão,
Hidrógrafa, Inundações,
Modelos hidrológicos
• Q - Volume de
água passando
por um ponto
por unidade de
área
• Q=VA ou WDV
Figure 1.18
modified from www.usda.gov/stream_restoration/chap1.html
Vazão e hidrógrafa
www.aquatic.uoguelph.ca/rivers/chphys.htm
Hidrógrafa Anual
Hidrógrafa de evento
Figure 1.14
www.usda.gov/stream_restoration/chap1.html
Efeitos da urbanização em uma hidrógrafa de evento
Figure 1.15
http://www.usda.gov/stream_restoration/Images/scrhimage/chap1/fig1-15.jpg
Caminhos do escoamento superficial
www.usda.gov/stream_restoration/chap1.html
Fig. - 2.10
Escoamento superficial
• 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
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
Inundações
• 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
• 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
• Rápido escoamento em rios canalizados aumenta
a frequencia de inundações e o pico na hidrógrafa
em pontos a jusante
www.aquatic.uoguelph.ca/rivers/chphys.htm
Associando Uso da Terra com a
Qualidade da Água
Menos Superfície Impermeável = Mais Água
Superfície Impermeável
• Fornece uma
superfície para
acumulação de
poluentes
• Leva ao aumento dos
poluentes via
escoamento e
inundação
• Inibe a recarga dos
aquíferos
Impactos das mudanças do uso da terra
Efeitos Hidrológicos
–
–
–
–
Ruptura do balanço natural da água
Aumento do pico de inundação
Aumento do escoamento superficial
Maior frequencia de inundações
Escoamento superficial e desenvolvimento
www.mmsd.com/stormwaterweb/Volume1B.htm
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, ……)
ln(a / tanB)
15
But numerical experiments suggest that
even small rates of recharge to deeper
layers can dramatically influence
patterns of wetness
13
11
9
7
5
CRWR
GIS in Water Resources
Consortium
GIS
Water
Resourc
es
Bringing together these two communities by using a
common geospatial data model
http://www.crwr.utexas.edu/giswr
ArcGIS Hydro Data Model
Hydrography
Hydrology
Maidment, 2002
National Hydro Data Programs
http://www.crwr.utexas.edu/giswr/nhdconf/nationalhydro.html
National Elevation Dataset
(NED)
Elevation Derivatives for
National Applications (EDNA)
National Hydrography Dataset
(NHD)
Watershed Boundary Dataset
Streams
Drainage Areas
Hydrography
Channels
Terrain Surfaces
Rainfall Response
Digital Orthophotos
Thematic
Layers
supporting the
Arc Hydro
data model
Michael Zeiler
“Modeling Our World”
How do we combine these
data?
Digital Elevation
Models
Watersheds
Streams
Waterbodies
Maidment, 2002
An integrated
raster-vector
database
Maidment, 2002
Integrating Data Inventory using
a Behavioral Model
Relationships between
objects linked by tracing path
of 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 have
Fortran
subroutines
in a DLL
Muskingum
flow routing
Maidment, 2002
Independent Hydrologic Model
VB progam reads and writes
text files
Maidment, 2002
Interfaces to Arc Hydro Data and Models
Analysis, Modeling,
Decision Making
Arc Hydro
Geodatabase
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
Maidment, 2002
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)
• 2015 HUC’s cover continental US
• average area ~ 1 county
Hydrologic Unit Code
= 12100203
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
San Marcos basin
National Elevation Dataset
30m x 30m cells
11,000,000 cells to cover San Marcos basin
70,000,000 cells to cover Guadalupe basin
Maidment, 2002
Drainage Area Delineated from
the Digital Elevation Model
Arc Hydro attribute DrainArea
Maidment, 2002
Estimating Naturalized Flow at
Diversion Points
Qf
Af
Qd
Ad
Naturalized flow record at
stream gage
(50 years of monthly
flows)
Estimated flow record at
diversion point
Qd = Qf
Ad
Af
Maidment, 2002
Length Downstream
Flow distance (D to F)
= Length Downstream (D)
– Length Downstream (F)
Length Downstream (F)
F
D
D
Seepage
losses
F
Arc Hydro attribute LengthDown
Length Downstream (D)
Maidment, 2002
Flood Hydrology and Hydraulics
ArcView
Input Data
DEM
HEC-GeoHMS
HEC-HMS
Flood
discharge
ArcView
Flood
plain maps
Hec-GeoRAS
HEC-RAS
Water
surface
profiles
Maidment, 2002
Stream Definition: Waller
Creek
Austin Watersheds with Streams
derived 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 Inlet
Connectivity
Maidment, 2002
Area to Area Connectivity:
SchematicLinks built using
NextDownID
Maidment, 2002
TIWSS
Texas Integrated Water Simulation
System
WRAP
Water Availability
SWAT
Water Quality
Arc Hydro
Geospatial and Temporal Data
HEC Models
Flooding & Water Management
Modflow
Groundwater
Maidment, 2002
Flood Plain Mapping
Maidment, 2002
Connecting HMS and RAS
Maidment, 2002
Flood Hydrology and Hydraulics
ArcView
Input Data
DEM
HEC-GeoHMS
HEC-HMS
Flood
discharge
ArcView
Flood
plain maps
Hec-GeoRAS
HEC-RAS
Water
surface
profiles
Maidment, 2002
HEC-RAS: Background
 River Analysis System model of the U.S. Army Corps of
Engineers
 Input = cross-section geometry and flow rates
 Output = flood water elevations
Cross-Section Schematic
Normal Water Surface
Flood Water Surface
Floodway
Left Bank Station
Floodway
Main
Channel
Right Bank Station
Maidment, 2002
Waller Creek
Watersheds
Network
Channel
Maidment, 2002
HEC-RAS: Cross-Section
Description
 Points describe channel
and floodway geometry
 Bank station locations
 Water surface
elevations and
floodplain boundaries
Maidment, 2002
Discharge at a Particular Cross-Section
Maidment, 2002
HEC-RAS: Output
Graphical
Text File
Maidment, 2002
Floodplain Mapping: Plan
View
Maidment, 2002
3D Terrain Modeling: Ultimate Goal
Maidment, 2002