The World of GIS Hydro ‘98

David R. MaidmentUniversity of Texas at Austin

Presented by:

GIS Hydrologic Modeling

Environmental description Process representation

Data

Input

Model

Results

Synthesis of GIS and Modeling

Linking Data and Models

Integrated Spatial Database GIS Hydro ‘98 Models

Watershed Characterization

Runoff & Routing

Hydraulics

Water Quality

Atmosphere & Soil Water

Traditionalapproach

SpatialHydrology

ProcessRepresentation

EnvironmentalDescription

Process-basedModeling

Map-basedModeling

Hydrologic Modeling

Users

Hydrologicsimulation

Timeseriesdata

Spatialhydrologicmodel

Spatialdata

RealWorld

Spatial Hydrologic Modeling Concept

t

t

t

I Q

t

Continuous time hourly, daily

Steady state mean annual

Seasonal monthly

Single event

Dealing with Time Variation

Two tasks:

I. Environmental descriptionusing a map

II. Process representationusing equations

Modeling Procedure

Environmentaldescription

Processrepresentation

1. Study design 2. Terrain analysis 3. Land surface description 4. Subsurface description 5. Hydrologic data representation 6. Soil water balance 7. Water flow 8. Constituent transport 9. Impact of water utilization 10. Presentation of results

Ten Step Procedure for Modeling

Objectives of the study? Range and subdivision of the spatial domain? Duration and subdivision of the time horizon? Variables to be computed?

Step 1. Study Design

Computationaleffort ~ LMN

LMN < 10,000,000for execution within ArcView

Number of:Spatial units = LVariables computed = MTime intervals = N

Time Variables

Space

N

M

L

Space, Time, and Process Variables

Mean annual flow andtransport on a raster grid

Time

Variables

SpaceN=1

M

L

Time-Averaged Modeling

LandCharacterization

(Land use,Soils,

Climate,Terrain)

Water Characterization(water yield, flooding, groundwater, pollution, sediment)

Relationships between land type and water characteristics

Land and Water Interaction

LandCharacterization

(Land use,Soils,

Climate,Terrain)

Non Point Source Pollution(mean annual flowsand pollutant loads)

Adapt Water to the Land System

Water Characterization(water yield, flooding, pollution, sediment)

LandCharacterization

(Land use,Soils,

Climate,Terrain)

Water Characterization(water yield, flooding, pollution, sediment)

CRWR-PrePro(GIS Preprocessorfor HEC-HMS floodhydrograph simulation)

Adapt Land to the Water System

CRWR-PrePro: HMS Preprocessor

Geographic Data Schematic Diagram

Increasing Scale Increasing Complexity

Digital Elevation Model (DEM)

Vector representation as points, lines and areas Raster representation on a grid of DEM cells

Vector

Raster

Outlet Stream Watershed

Raster-Vector Equivalence

+ =

Take a mapped stream network and a DEM Make a grid of the streams Raise the off-stream DEM cells by an arbitrary elevation increment Produces "burned in" DEM streams = mapped streams

“Burning In” the Streams

Begin with an elevation grid Flow in direction of steepest descent

Eight-Direction Pour Point Model

78 72 69 71 58 49

74 67 56 49 46 50

69 53 44 37 38 48

12

21

22

11

16

31

12

19

24

53

61

58 55

47

34

68

74

64

Elevation Flow direction grid

Flow Direction Grid

Flow Direction

Water flows to one of its neighbor cells according to the direction of the steepest descent.

Flow direction takes one out of eight possible values.

Flow direction gridImplied network

between cell centers

Grid Network

0 0 0 0 0 0

0 1 1 2 2 00 3 7 5 4 0

71

20

3524

0

10

1

20

0 0

04

00

0

Number ofupstream cells

Classification of flow accumulation

Number of cells > 6 = stream0 cells = watershed boundary

1 1 2 2

3 7 5 4

7

1

20

35

24

1

1

2 4

Flow Accumulation Grid

Flow Accumulation

Flow accumulation is an indirect way of measuring drainage areas (in units of grid cells).

Types of Outlets and Nodes

Stream junction node

Stream headwater node

System outlet node

User-defined nodeSub-basin

Stream

Stream Segmentation

Stream segments (links) are the sections of a stream channel connecting two successive junctions, a junction and an outlet, or a junction and the drainage divide.

Watershed Delineation

The drainage area of each stream segment is delineated.

What DEM cell size to use? Cell size = Region area / 1,000,000

What size watershed to delineate? Watershed > 1000 cells

Thousand-Million Rule

Cell Size WatershedArea (km2)

TypicalApplication

1” (~ 30 m) 3” (~ 100 m)15” (~ 500 m)30” (~ 1 km) 3’ (~ 5 km) 5’ (~ 10km)

540

10004000

150,000400,000

Urban watershedsRural watershedsRiver basins, StatesNationsContinentalGlobal

Application of Digital Elevation Models

Raster to Vector Conversion

Streams and watersheds are converted from raster to vector format.

Dissolving Spurious Polygons

Cells connected to the main watershed polygon through a corner are defined as a separate polygon (spurious polygon).

These polygons are dissolved into the main polygon.

Watershed Parameters

Flow length upstream and downstream

AverageCurve Number

Slope and length of the longest flow-

path

Identification of the longest flow-path

Lag-timeSCS Unit

Hydrograph

distance downstream to outlet

Flow-Length Function in ArcView

distance to upstream divide

Flow Length Downstream to the

Watershed Outlet

Flow Length Upstream to the Watershed

Divide

Longest Flow-PathTotal flow length = upstream length + downstream length

V21

V11

V41

V31

V61

V51

V32

V12

V22

V42

V52

V62

V23

V13

V33

V53

V43

V24

V16V15V14

V63

V34

V44

V54

V64

V25

V35

V45

V55

V65

V26

V36

V46

V56

V66

Velocity magnitude Velocity direction

V = aSb

S = slopea,b = land cover coefficients

Velocity Field

time to outlet (weighted flow length)

Time = Distance x1

Velocity

Flow Time Computation

Isolation of a Sub-System

Connection to HEC-HMS

HMS Schematic Parameter Transfer

HMS Basin File

Ferdi’s code

Upper Mississippi Flood Study

Streams and Subwatersheds

162 subwatershedseach with a USGS gage at the outletdefined using 15” (500m) DEM

Rivers definedby EPA RiverReach File 1 (RF1)

CRWR-Prepro Schematic Network

Inlets

Mississippi River

Missouri River

Outlet (Mississippi R.at Thebes, Ill)

HEC-Hydrologic Modeling System

HMS Basin file

CRWR-PrePro HEC-HMS Model Schematic

LandCharacterization

(Land use,Soils,

Climate,Terrain)

Non Point Source Pollution(mean annual flowsand pollutant loads)

Adapt Water to the Land System

Water Characterization(water yield, flooding, pollution, sediment)

Land-WaterConnection

TransformCoefficient

Water yield Runoff coefficient, C

Flood runoff SCS Curve Number, CN

Groundwater Recharge rate (mm/yr)

Water quality Expected Mean Concentration(mg/l)

Sediment yield Erosion rate (tons/ha-yr)

Possible Land-Water Transform Coefficients

Water

Land

Map-Based Surface Water Runoff

Runoff, Q (mm/yr)

Precipitation, P(mm/yr)

Accumulated Runoff (cfs)

P

Q

Runoff CoefficientC = Q/P

Water Quality: Pollution Loading Module

DEMPrecip. Runoff

LandUse

EMC Table

ConcentrationLoad

AccumulatedLoad

Load [Mass/Time] = Runoff [Vol/Time] x Concentration [Mass/Vol]

Expected Mean Concentration

Constituent Resident. Comm. Indust. Transp. Agric. Range UndevelTotal Nitrogen (mg/l) 1.82 1.34 1.26 1.86 4.40 0.70 1.50Total Phosphorus (mg/l) 0.57 0.32 0.28 0.22 1.30 <0.01 0.12Oil and Grease (mg/l) 1.7 9.0 3.0 0.4Copper (ug/l) 15.0 14.5 15.0 11.0 1.5 <10Chromium (ug/l) 2.1 10.0 7.0 3.0 <10 7.5Zinc (ug/l) 80 180 245 60 141 16 6

Land Use

EMC

Table derived from USGSwater quality monitoring sites

Total Constituent Loads

Input for WaterQuality Model

Water Quality: Land Surface -Water Body Connection

Bay Water Quality

Flood Hydraulics

Given the flood discharge (HEC-HMS), what is the water surface elevation (HEC-RAS, River Analysis System)

How to draw flood plain maps?

HEC-RAS

AVRAS

Cross-sectionmapping

Flood Hydraulics: Stream Geometry Data

Determine cross-section elevations from TIN terrain data HEC-RAS pre- and post-processing using avRAS (ArcView) or

HEC AMLs (Arc/Info) Visualize floodplain TINs with ArcView’s 3D Analyst extension

asfloodrises

Hydraulics: RAS Stream Geometry Data

Digital orthophoto serves as a base map upon which to digitize the stream

Avenue scripts create an ArcView cross-section table from the HEC-RAS output text file

Link cross-section table records to cross-section locations on the digitized stream

GIS - River Analysis System (AVRAS)

Pre Processor(Avenue)

GIS

GIS RAS Import

RAS 2.0

GIS RAS Export

Post Processor(Avenue)

GIS

Hydraulic Input

Dean Djokic& Zichuan Ye

(ESRI)

Stream Bed Shape in ArcView

Cross-sections

Flood Plain in HEC-RAS

Floodplain in ArcView

Floodplain in ArcView 3-D Analyst

Spatial Hydrology Virtual Campus Courses

ESRI Virtual Campus course on Spatial Hydrology (http://campus.esri.com/campus/home/home.cfm)

University of Texas GIS in Water Resources online course during Fall 1998 (limited enrollment) (http://www.ce.utexas.edu/prof/maidment)

DHI: Hydraulic & Water Resources Engineering

MIKE SHEMIKE SHEMIKE BASINMIKE BASIN

MIKE 11MIKE 11MOUSEMOUSE

DHI Models

Pipe Networks

River Basin Networks 1-D River Modeling

Hydrologic Modeling

Danish Hydraulic Institute

BYU: Surface and Groundwater Flow

Integrates digital terrain models with standard

runoff models such as HEC-1, TR-20, TR-55.

Subsurface Representation and Model Interface for Groundwater Simulation: MODFLOW, MT3D, MODPATH, SEEP2D, and FEMWATER.

Two-Dimensional Surface Water Model Interface for RMA2, RMA4, RMA10, HIVEL2D, FLO2DH (FESWMS), ADCIRC, CGWAVE, WSPRO, SED2D-WES, and DAMBRK.

Brigham Young University

EPA: Water Quality

TOXIROUTE

NPSM QUAL2E

US Environmental Protection Agency

ArcViewPreprocessor forWater Quality Models