archydro – two components hydrologic data model toolset credit – david r. maidment university...
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ArcHydro – Two Components
Hydrologic Data Model Toolset
Credit – David R. Maidment University of Texas at Austin
ArcHydro – Data Model
Hydrography
Network
Channel
Drainage
HydroFeatures
Based on inventory of all features for an area
Behavioral model – trace direction of water movement across landscape
Credit – David R. Maidment University of Texas at Austin
Developed with National Hydrogrophy Dataset (NHD) in mindTools intended to be used with NHD
Integrated raster-vector database
ArcHydro – Data Model
Credit – David R. Maidment University of Texas at Austin
ArcHydro - Tools
Set of tools used to derive end-productsFlow networkHydrologically conditioned DEM
Iterative, step-by-step approach with required inputs
Raster several formats, vector utilizes geodatabase only
ArcHydro - Tools Set of tools used to
achieve end-productsFlow networkHydrologically conditioned
DEMCatchment delineation
Iterative, step-by-step approach with required inputs
Raster several formats, vector utilizes geodatabase only
Credit – David R. Maidment University of Texas at Austin
ArcHydro Pros
Semi-automated derivation of key products
Semi-supportedFreeIntegrates data from
multiple sources and of different types
Cons Semi-automated Install can be difficult User interpretation
and editing introduces subjectivity
Need to know what default settings mean
Few training resources
Hydrologic Applications
Hydrologic Modeling
Process-based - try to represent the physical processes observed in the real world
Dozens available – TOPMODEL, SWAT, HSPF, etc.
Variables - Surface runoff, evapotranspiration, etc.
Increasing GIS integration
Predict response of hydrologic systems to changing variables, i.e. precipitation
Credit – Pajaro Valley Water Management Agency
Hydrologic Modeling - Hydraulics
Model hydraulics of water flow over land and through channels
Assess peak discharge, volume estimates, runoff curve numbers, etc.
HEC-RAS Increasingly GIS-based
or integrated
Erosion AnalysesLocate sites of likely gully
and other streambank interface erosion
Terrain Analysis approach – Stream Power Index (SPI)
High SPI values indicate high potential overland flow
Quantitative, spatial, repeatable
Water StorageUtilize LiDAR to accurately
identify size, depth, and location of depressions in the landscape
Reduce Peak Flows Reduce sediment and
nutrients transported downstream
Water StorageNRCS will have tools
available in the future to better calculate
Rough calculation Perform Pit-fill Subtract original
DEM from pit-filled DEM to locate larger depressions
Multiple methods for determining volume
Floodplain Mapping/DelineationNational Flood Insurance Program Local communities regulate development
in floodplains Requires accurate floodplain maps
100 Year Flood boundaryKeep building out of 100 year inundation area
Administered by FEMA Utilizes Flood Insurance Rate Map (FIRM) Update process to digital (DFIRM)
Floodplain Mapping/Delineation
Credit – FEMA
Mimic flooding at various stages to determine land area and locations inundated
Flood Inundation Area Mapping
Needs• Highly accurate land
elevation data – LiDAR DEM
• Modeling Capabilities- Hydraulic Engineering Center–River Analysis System (HEC–RAS)
• Stream-gauge heights/peak-flow readings
Flood Inundation Area Mapping
LiDAR DEM
Hydrologic Conditioning
Calibration
Stream gauge Data
Model (HEC-RAS)
Conditioned DEM
Flood Surface Elevations
Inundation Area Map
Credit – USGS
Flood Inundation Area MappingHydrologic Conditioning - Key
Credit – USGS