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BY ASHISH AGRAWALBY ASHISH AGRAWAL
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Why we need this tool?Why we need this tool?
Inputs, Outputs and How it works?Inputs, Outputs and How it works?
Comparison to other toolsComparison to other tools
Capabilities of toolCapabilities of tool
Future workFuture work
AcknowledgementAcknowledgement
OVERVIEWOVERVIEW
WHY WE NEED IT?WHY WE NEED IT? *
HEC – HMS (Hydrologic Modeling System) : Simulates HEC – HMS (Hydrologic Modeling System) : Simulates
precipitation –runoff processes for dendritic watershed precipitation –runoff processes for dendritic watershed
systemssystems INPUT - TEXT FILES (BASIN, METEOROLOGICAL , CONTROL, etc.)INPUT - TEXT FILES (BASIN, METEOROLOGICAL , CONTROL, etc.)
OUTPUT – HYDROGRAPH (TABLES, GRAPHS)OUTPUT – HYDROGRAPH (TABLES, GRAPHS)
BASIN FILE : Physical data describing the watershed, BASIN FILE : Physical data describing the watershed,
e.g. subbasin, streams, longest flow path, slopes, etc.e.g. subbasin, streams, longest flow path, slopes, etc.
METEOROLOGICAL FILE : Precipitation and METEOROLOGICAL FILE : Precipitation and
evapotranspiration dataevapotranspiration data
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WHY WE NEED IT? (Contd...)WHY WE NEED IT? (Contd...)Extracting hydrologic information from Extracting hydrologic information from
digital spatial data - create formatted text digital spatial data - create formatted text
files – Readable by HMSfiles – Readable by HMS
Automating saves Time and MoneyAutomating saves Time and Money
Useful for future predictions – Change in Useful for future predictions – Change in
Landuse, Impervious cover percentage.Landuse, Impervious cover percentage.
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INPUT/OUTPUTINPUT/OUTPUT
THRESHOLD THRESHOLD FOR STREAM FOR STREAM DEFINITIONDEFINITION(In number of (In number of cells)cells)
DEM
NHD STREAMS
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IDM (Interface Data Model)
HEC-HMSMask
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PrePro (ArcView 3.x)PrePro (ArcView 3.x)
Written in Avenue ( Scripting Language)Written in Avenue ( Scripting Language)
Linear ProcedureLinear Procedure
HEC-GeoHMS ( ArcView 3.x)HEC-GeoHMS ( ArcView 3.x)
Written in AvenueWritten in Avenue
Linear ProcedureLinear Procedure
PrePro2002 (ArcView 8.x)PrePro2002 (ArcView 8.x)
Written in Visual BasicWritten in Visual Basic
Linear ProcedureLinear Procedure
PrePro2004 (ArcView 8.x)PrePro2004 (ArcView 8.x)
Exploiting GeoDatabase conceptExploiting GeoDatabase concept
Improvements over PrePro2002Improvements over PrePro2002
COMPARISIONCOMPARISION
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DEM
PATH SETUP
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DEM/Mask/BurnIn
Projection: DEM should be projectedCould change Z-unit
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DEM/Mask/BurnInRawDEM
Mask
Streams for BurnIn
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FIL/FDIR/FACCTargetDEM
BurnedDEM
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FDIR
3232 6464 128128
1616 11
88 44 22
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FACC
Flow Accumulation Grid :Flow Accumulation Function counts the number of cells upstream of a particular cell
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STREAMS/OUTLET
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STREAMS/OUTLET
Extracted Flow Accumulation Grid : (extflowacc)Flow Accumulation values which are greater than threshold
Stream Link Grid : (strgrid)Streams are divided into links with unique identification number
Outlet Grid : (out)Outlet points of the stream links, which is most downstream point of every link
Vectorized : Out(grid) -------> outlet (shapefile)Strgrid (grid) ------> Reach (shapefile)
outlet
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STREAMS/OUTLET
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ADD STREAMS
RAIN DROP TOOL :Helps in adding stream by creating graphics
New streams
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ADD Inlet/Outlet/Reservoirs
• Break stream links
INLETSINLETS• Get rid of every-thing upstream
RESERVOIRSRESERVOIRS•Pose restrictionswhen merging
Reservoir
OutletInlet/Source
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Delineate Watershed
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HMS Elements
HMSSubbasinHMSReachHMSJunctionHMSSourceHMSReservoir
OutletsJunction
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Merging Subbasins
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Merging Subbasins
91
92
91
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Calculate Parameters
SUBBASIN PARAMETERSSUBBASIN PARAMETERSLongest Flow Path
LengthSlope of LFP
Full length10 – 85 % length
U/S Elevation D/S Elevation
Centroid of SubbasinsElevation at Centroid
Centroidal Flow Length
REACH PARAMETERSREACH PARAMETERSLength of ReachSlope of ReachU/S Elevation D/S Elevation
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Curve Number
Curve Number: SCS Curve Number method uses CN to determineamount of runoff for given amount of rainfall.
How?Intersection of Landuse (Shapefile), Soiltype (Shapefile) and watershed (Shapefile)Lookup Table
•Change Impervious Cover percentage – Modify Curve Number
• Edit Landuse • Edit Soiltype
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Tool/IDM
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IDM to HMS
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HMS Files
Subbasin: R00 Canvas X: 614903.792 Canvas Y: 3364445.138 Label X: Label Y: Area: 0.05 DownStream: J0End:
Junction: J0 Canvas X: 615194 Canvas Y: 3364208 Label X: Label Y: DownStream: R460End:
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HMS Basin Model
GIS GIS HEC-HMS HEC-HMS
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Future Work
• Calculate some more parameters - required by HMS • Modify Curve Number – Antecedent Moisture Condition (AMC)• Create Meteorological files (in progress)
Preliminary Milestones
Final Destination
• Delineate Flood Plain Map
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Conclusion
• Automating – Less Time & Money
• Predicting future changes will be easy
• IDM can maintain different scenarios for
comparison
• Better data, advance algorithms – may
attain greater accuracy over traditional
method
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Acknowledgment
• Dr. Francisco Olivera
• For his guidance and support
• Janghwoan Choi
• Used some modules from his code
• Srikanth Koka
• Used some of the snapshots from exercise
created by him
• http://www.hec.usace.army.mil/software/hec-hms/
hechms-hechms.html
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Questions
?
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