UC 2006 Tech Session 1 David Maidment Steve Kopp Nawajish Noman Dean Djokic Louis Wasson GIS Hydro...

UC 2006 Tech SessionUC 2006 Tech Session11

David MaidmentSteve Kopp

Nawajish NomanDean Djokic

Louis Wasson

GIS Hydro 2006 Part 1

An Introduction to GIS and Surface Hydrology


OutlineOutline

• Hydrology overviewHydrology overview• GIS tools and data for hydrology – the building blocksGIS tools and data for hydrology – the building blocks• GIS data models and specialized tools (ArcHydro)GIS data models and specialized tools (ArcHydro)• 10:15 Break10:15 Break• A user’s perspective on ArcHydroA user’s perspective on ArcHydro• Hydrologic modelingHydrologic modeling• Hydraulic modelingHydraulic modeling


Water Resources OverviewWater Resources Overview

• 2 broad categories of terrestrial water2 broad categories of terrestrial water– Surface waterSurface water– GroundwaterGroundwater

• 2 broad categories of water modeling2 broad categories of water modeling– QuantityQuantity– QualityQuality

• Today’s focus Today’s focus surface water quantitysurface water quantity


Surface Water QuantitySurface Water Quantity

• How much water is there?How much water is there?– Rainfall-runoff modeling, a type of hydrologic modeling, Rainfall-runoff modeling, a type of hydrologic modeling,

determines for a given storm on a landscape, how much water will determines for a given storm on a landscape, how much water will become runoff.become runoff.

• Where will it go?Where will it go?– Hydraulic modeling takes the quantity of water and the shape of Hydraulic modeling takes the quantity of water and the shape of

the landscape and stream channel and determines how deep the the landscape and stream channel and determines how deep the water will be and what area it will cover in the event of a flood.water will be and what area it will cover in the event of a flood.


Hydrologic ModelingHydrologic Modeling

• GoalGoal:: Find stream discharge, Find stream discharge, QQ, at a location for a given , at a location for a given precipitation.precipitation.

• GIS is used to summarize terrain and hydrologic GIS is used to summarize terrain and hydrologic characteristics of the watershed for input to a model.characteristics of the watershed for input to a model.

• Many ways to calculate Q.Many ways to calculate Q.– Statistical methodsStatistical methods

• USGS regression equations (NFF, StreamStats)USGS regression equations (NFF, StreamStats)

– ““Physical” modeling (rainfall-runoff models)Physical” modeling (rainfall-runoff models)• HEC-HMS (successor to HEC-1), etc.HEC-HMS (successor to HEC-1), etc.


Hydrologic ModelingHydrologic Modeling

• Map natural processes onto software tasksMap natural processes onto software tasks• Aggregate landscape characteristics to simplifyAggregate landscape characteristics to simplify

– ““Lumped parameter model”Lumped parameter model”


Hydraulic ModelingHydraulic Modeling

• Goal:Goal: to predict water surface elevations for the creation to predict water surface elevations for the creation of flood inundation maps.of flood inundation maps.– Also predict velocity, sedimentation, qualityAlso predict velocity, sedimentation, quality

• Input:Input: channel and floodplain geometry with hydraulic channel and floodplain geometry with hydraulic characteristics, plus discharge and initial water surface characteristics, plus discharge and initial water surface level.level.

• Output:Output: water surface elevation at each cross section and water surface elevation at each cross section and other characteristics.other characteristics.


GIS Data for Hydrologic and GIS Data for Hydrologic and Hydraulic ModelingHydraulic Modeling

• Digital Elevation ModelDigital Elevation Model• http://seamless.usgs.gov/ http://seamless.usgs.gov/ • http://edna.usgs.gov/ http://edna.usgs.gov/

• Watershed boundariesWatershed boundaries• http://www.ncgc.nrcs.usda.gov/products/datasets/watershed/http://www.ncgc.nrcs.usda.gov/products/datasets/watershed/

• HydrographyHydrography• http://nhd.usgs.gov/ http://nhd.usgs.gov/

• SoilsSoils• http://www.ncgc.nrcs.usda.gov/products/datasets/statsgo/ http://www.ncgc.nrcs.usda.gov/products/datasets/statsgo/ • http://soildatamart.nrcs.usda.gov/ http://soildatamart.nrcs.usda.gov/

• LandcoverLandcover• http://seamless.usgs.gov/ http://seamless.usgs.gov/

• Current and historic water recordsCurrent and historic water records• http://waterdata.usgs.gov/nwis http://waterdata.usgs.gov/nwis • http://www.epa.gov/STORET/index.htmlhttp://www.epa.gov/STORET/index.html

• Climate, weather, rainfallClimate, weather, rainfall• http://www.ncdc.noaa.gov/oa/ncdc.html http://www.ncdc.noaa.gov/oa/ncdc.html • http://www.nws.noaa.gov/ndfd/ http://www.nws.noaa.gov/ndfd/

• Channel geometry (cross sections)Channel geometry (cross sections)


Elevation DataElevation Data

• TypesTypes– DEM : Digital Elevation ModelDEM : Digital Elevation Model– DSM : Digital Surface ModelDSM : Digital Surface Model

• Data StructureData Structure– RasterRaster– TINTIN


Where do you get DEM data?Where do you get DEM data?

• SourcesSources– USGS DEM, NED, DTED, ETOPO30, SRTMUSGS DEM, NED, DTED, ETOPO30, SRTM– Interpolated from points and linesInterpolated from points and lines– Generated photogrammetricallyGenerated photogrammetrically– LiDARLiDAR

• Created with interpolation toolsCreated with interpolation tools– especially TOPOGRID, TopoToRaster especially TOPOGRID, TopoToRaster

• What cellsize and accuracy?What cellsize and accuracy?– Horizontal and Vertical resolution must be appropriate for the Horizontal and Vertical resolution must be appropriate for the

landscape and scale being modeled.landscape and scale being modeled.


• DEM construction issuesDEM construction issues– Resolution and extentResolution and extent– Projection (for hydrology - equal area)Projection (for hydrology - equal area)– Source elevation dataSource elevation data– Interpolation techniques (IDW, spline, via TIN)Interpolation techniques (IDW, spline, via TIN)

• Problems with contour inputProblems with contour input– Specialized DEM construction software/components Specialized DEM construction software/components

(ANUDEM, TOPOGRID, (ANUDEM, TOPOGRID, TopoToRasterTopoToRaster))

DEM ConstructionDEM Construction


Drainage SystemDrainage System

Watershed (Basin, Catchment, Contributing area) Watershed Boundaries

(Drainage Divides)

Pour Points (Outlets)


GIS Tools for Describing GIS Tools for Describing Surface Water MovementSurface Water Movement

DEMDEM

FLOW DIRECTION

SINK

FILL

FLOWLENGTH

FLOW ACCUMULATION

WATERSHED

SNAP POUR

DepressionlessDepressionlessDEMDEMAre there any sinks?Are there any sinks?

NoNo

YesYes

STREAM LINE

STREAM ORDER

STREAM LINKAp

ply

Th

resh

old

Ap

ply

Th

resh

old


Flow DirectionFlow Direction

64 128

116

8 24

32

128 128

2

2 2

2

2

2

4

4

4

8

1 1 2

1

4

2

8

4

4

8

2

1

2

1

1

1

4

1

4

4

4

16

4

878

74

72

67

69

56

71

49

58

50

69

64

53

58

44

55

37

22

38

31

48

24

68

74

61

53

47

34

21

12

16

11

19

12

46

49

ElevationElevation

Direction CodingDirection Coding

Flow DirectionFlow Direction


Flow AccumulationFlow Accumulation

0

0

0

1

0

1

0

2

0

0

0

0

3

0

7

0

5

20

4

0

0

1

0

0

0

2

0

4

1

7

24

35

0

2

2

0

64 128

116

8 24

32

Direction CodingDirection Coding


Function ProcessingFunction Processing

DEMDEM

FLOW DIRECTION

SINK

FILL

FLOWLENGTH

FLOW ACCUMULATION

WATERSHED

SNAP POUR

DepressionlessDepressionlessDEMDEMAre there any sinks?Are there any sinks?

NoNo

YesYes

STREAM LINE

STREAM ORDER

STREAM LINKAp

ply

Th

resh

old

Ap

ply

Th

resh

old


Creating Vector StreamsCreating Vector Streams

11 11

11 22 22

22 22 22 22

22 22

Value = No Data

NET_GRID

StreamToFeatureStreamToFeature

RasterToFeatureRasterToFeature


Stream LinkStream Link

• Assign a unique value to each stream Assign a unique value to each stream segment.segment.– Can be used as input to Watershed toolCan be used as input to Watershed tool


Stream OrderingStream Ordering

StrahlerStrahler ShreveShreve

33

11

11

11 11

1111

11

22 22

22 22

22

44

77

11

11

11

1111

1111

22

22

33

33


WatershedWatershed

• Delineate the contributing area to a cell or Delineate the contributing area to a cell or group of cells.group of cells.


SnapPourSnapPour

• Snap the “pour point” of a watershed to the cell of Snap the “pour point” of a watershed to the cell of highest flow accumulation within a neighborhood.highest flow accumulation within a neighborhood.– Prevents accidental creation of tiny watersheds on channel Prevents accidental creation of tiny watersheds on channel

side slopes.side slopes.

Snap distanceSnap distance

Cell you clicked onCell you clicked on

The cell that will be selected(cell with highest flow accumulation)The cell that will be selected(cell with highest flow accumulation)

Stream

Stream


Flow LengthFlow Length

• Calculate the length of the upstream or Calculate the length of the upstream or downstream flow path from each cell.downstream flow path from each cell.


Using the tools in ModelBuilderUsing the tools in ModelBuilder


DEM Errors – Sinks and SpikesDEM Errors – Sinks and Spikes

• Sinks: when sinks are (or are not) Sinks: when sinks are (or are not) sinks – lakes, depressions, …sinks – lakes, depressions, …– Global fillGlobal fill– Dealing with internal basinsDealing with internal basins– Selective fillSelective fill

• DepthDepth

• AreaArea

SinkSinkFilled sinkFilled sink


DEM EditingDEM Editing

• Streams: when streams are not where they Streams: when streams are not where they “should” be“should” be–Flat areas – difficulty in determining the flow patternFlat areas – difficulty in determining the flow pattern–Barriers (roads) diverting the flow pathsBarriers (roads) diverting the flow paths

• How to “model” bridges and culverts in DEMHow to “model” bridges and culverts in DEM• How to model damsHow to model dams

– Imposing the flow pattern - to burn or not to burn Imposing the flow pattern - to burn or not to burn (beware of the scale issues and artifacts – Saunders, (beware of the scale issues and artifacts – Saunders, 2000)2000)• Simple burnSimple burn• AGREEAGREE• OMNROMNR


DEM Editing DEM Editing (cont.)(cont.)

• Boundaries - when watershed boundaries are not Boundaries - when watershed boundaries are not where they “should” bewhere they “should” be–To fence or not to fenceTo fence or not to fence– Ineffective flow areasIneffective flow areas


DEM Editing DEM Editing (cont.)(cont.)

• ToolsTools–Global operatorsGlobal operators

• FillFill• Agree (burn/fence)Agree (burn/fence)• OMNR (when it becomes available)OMNR (when it becomes available)• SWFWMDSWFWMD• Custom – model builderCustom – model builder

–MicromanagementMicromanagement• DEM Editing toolsDEM Editing tools• Custom – model builderCustom – model builder


Enhanced Flow DirectionEnhanced Flow Direction (OMNR – Kenny & Matthews) (OMNR – Kenny & Matthews)

• Main stepsMain steps– Standard flow directions (D8)Standard flow directions (D8)– A hybridized raster/vector A hybridized raster/vector

topological analysis to assign D8 topological analysis to assign D8 flow directions to cells that intersect flow directions to cells that intersect the network.the network.

– An iterative raster single cell dilation An iterative raster single cell dilation and D8 assignment from within and D8 assignment from within water bodies to focus flow towards water bodies to focus flow towards the virtual segments.the virtual segments.

– A merging of results from steps 1, 2 A merging of results from steps 1, 2 and 3 to produce a final “enhanced and 3 to produce a final “enhanced flow direction grid”.flow direction grid”.


Summarizing Watershed CharacteristicsSummarizing Watershed Characteristics(Zonal Statistics)(Zonal Statistics)

• A A zonezone is all the areas/cells with the same is all the areas/cells with the same value.value.

• Calculate a statistic within the zones for each Calculate a statistic within the zones for each cell in a raster. cell in a raster.

• Input zones can be feature or raster.Input zones can be feature or raster.• Output as a raster, summary table, or chart.Output as a raster, summary table, or chart.

–Max flow length per watershedMax flow length per watershed–Average slope per watershedAverage slope per watershed–Average curve number per watershedAverage curve number per watershed


Zonal Overlay (cont.)Zonal Overlay (cont.)

SlopeSlope

WatershedsWatersheds

Mean Slope per WatershedMean Slope per Watershed


Where is this functionality?Where is this functionality?

• ArcInfo GRID FunctionsArcInfo GRID Functions• ArcView 3.x Spatial AnalystArcView 3.x Spatial Analyst

– Avenue requestsAvenue requests– Sample extensionSample extension

• ArcGIS Spatial Analyst 8.xArcGIS Spatial Analyst 8.x– HydrologyOp containing ArcObjects methodsHydrologyOp containing ArcObjects methods– Sample Toolbar on ArcObjectOnlineSample Toolbar on ArcObjectOnline– ArcHydroArcHydro data model tools data model tools

• ArcGIS Spatial Analyst 9.xArcGIS Spatial Analyst 9.x– Tools in the Spatial Analyst ToolboxTools in the Spatial Analyst Toolbox


Demonstration of Spatial Analyst Demonstration of Spatial Analyst Hydrology ToolsHydrology Tools

UC 2006 Tech Session 1 David Maidment Steve Kopp Nawajish Noman Dean Djokic Louis Wasson GIS Hydro...

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