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A Simple Drainage Enforcement Procedure for Estimating Catchment Area Using DEM Data. David Nagel, John M. Buffington , and Charles Luce U.S. Forest Service, Rocky Mountain Research Station Boise Aquatic Sciences Lab Boise, ID October 20, 2011. Study Area. Middle Fork Salmon River. - PowerPoint PPT Presentation
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A Simple Drainage Enforcement Procedure for Estimating
Catchment Area Using DEM Data
David Nagel, John M. Buffington, and Charles Luce
U.S. Forest Service, Rocky Mountain Research StationBoise Aquatic Sciences Lab
Boise, ID
October 20, 2011
Study Area
10,000 km of rivers and
streams
~ 1,000 km used by salmon
Middle Fork Salmon River
Our Purpose Estimate catchment area
Discharge
Grain size
Salmon spawning habitat
Data
10 m NED DEM dataset
NHD stream lines
http://ned.usgs.gov/
http://nhd.usgs.gov/
Problem
Flow accumulation lines from DEMs do not match vector stream lines
NHD stream
DEM flow line
Drainage Enforcement Objective
Recondition the DEM so all cells drain toward the stream and downstream
Non-enforced Enforced
Foundation of Watershed Analysis1) Fill
2) Flow direction
3) Flow accumulation
Fill Direction Accumulation
Flow Accumulation
Counting up the number of cells that contribute to a location on the stream = catchment area
1,00012,000
Raster Accumulation to Vector
Raster accumulation
12,000 cells
Attribute corresponding vector
Mismatch Between Raster and Vector Without Enforcement
EnforcedNon-enforced
Can’t attribute vector if data are mismatched
Why the DEMs and Stream Lines Do Not Match in Flat Valleys
DEM Production Process
1) Aircraft 2) Aerial photo 3) Stereo plotter
4) Map production 5) Scan and tag 6) LT4XLT4X, Infotec Development, Inc.
Original Contours and 10 m DEM Model
Original 40’ contours 2 m contours derived from 10 m DEM
LT4X
Blue box = 100 m x 100 m
500 m
Original Contours and 10 m DEM Model With Streams
Original 40’ contours 2 m contours derived from 10 m DEM
LT4X
LT4X made the DEMs from the original contours
There were no contours in flat valleys, so there wasn’t information for generating
the DEM data
Cartographers drew stream lines where they saw them,
independent of the LT4X model
Why Not Use LiDAR?
Site scale vs. landscape scale
Drainage Enforcement Algorithms1) ANUDEM - ArcGIS
2) AGREE – Arc Hydro Tools
3) IDDEA – Forest Service
ANUDEMImplemented by ArcGIS
(Topo to Raster)• Not designed for reconditioning DEMs directly -
requires contour lines or point input• Contour file sets may become too large• Avoids “trenching”
Hutchinson, M.F., 1989. A New Procedure for Gridding Elevation and Stream Line Data with Automatic Removal of Spurious Pits. Journal of Hydrology, 106:211-232.
AGREE Algorithm Implemented by Arc Hydro Tools
Dewald, T., NHDPlus User Guide, U.S. EPA and USGS, April 29, 2008
Hellweger, F., 1997. AGREE — DEM surface reconditioning system. Center for Research in Water Resources
Drainage Enforcement with AGREE
Original Reconditioned• Arcs must point downstream• Sharp drop may modify watershed boundaries• Uses “trenching”
IDDEA MethodInverse Distance Drainage Enforcement
Algorithm1) Grid stream lines2) Generate Euclidean distance from all stream lines3) Drop stream by constant value (e.g. 200 m) and4) Invert distance, multiply by constant: (1/d) * 1000 5) Subtract result from original DEM
Where cij, 200, else eij – ((1 / dij) * 1000)
cij is a stream channel cell at raster location ijeij is the elevation at ijdij is the Euclidean distance at ij
1) Grid Stream Lines
Vector to raster conversion
2) Euclidean Distance from Streams
3) Inverse Euclidean Distance
• Force constant drop (200 m) at stream channel• Enforcement decreases away from the
channel
(1/d) * 1000
200
0.02
200100
5010
0.1
Value decreases(unitless)
DEM Minus Inverse Distance
minus =
Profile Results
Preserves relative topography and
watershed boundaries
Run Flow Accumulation
Enforced
Non-enforced
Attributing Vectors
EnforcedNon-enforced
Higher probability of accurately attributing vectors with the correct contributing area
Results Comparison
0 100 200 300 400 500 600 700 800 900 10000
100
200
300
400
500
600
700
800
900
1000f(x) = 0.998441428124002 x + 7.68333422256683R² = 0.999863789909996
Catchment Area Comparison
IDDEA Catchment Area (HA)
Non
-enf
orce
d C
atch
men
t Are
a (H
A)
Disadvantages of the IDDEA Method
1) “Trenches” the DEM2) Meander bends smaller than cell size get
cut off and reroute flow
“Trenching” Cut-offs
Advantages of the IDDEA Method
1) Works relatively quickly at landscape scales
2) Preprocessing of raster or vector data is not required
3) Preserves relative topography and watershed boundaries
Thank you