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

5

7

9

11

13

15

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

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)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

Maidment, 2002

Discharge at a Particular Cross-Section

Maidment, 2002

HEC-RAS: OutputText FileGraphical

Maidment, 2002

Floodplain Mapping: Plan View

Maidment, 2002

3D Terrain Modeling: Ultimate Goal

Maidment, 2002