A Simple Drainage Enforcement Procedure for Estimating Catchment Area Using DEM Data

Transcription

1 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 NW GIS User Conference, Oct , Boise, ID October 20, 2011

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3 Study Area Middle Fork Salmon River 10,000 km of rivers and streams ~ 1,000 km used by salmon

4 Our Purpose Estimate catchment area Discharge Grain size Salmon spawning habitat

5 Data 10 m NED DEM dataset NHD stream lines

6 Problem NHD stream DEM flow line Flow accumulation lines from DEMs do not match vector stream lines

7 Drainage Enforcement Objective Non-enforced Enforced Recondition the DEM so all cells drain toward the stream and downstream

8 Foundation of Watershed Analysis 1) Fill 2) Flow direction 3) Flow accumulation Fill Direction Accumulation

9 Flow Accumulation 1,000 12,000 Counting up the number of cells that contribute to a location on the stream = catchment area

10 Raster Accumulation to Vector Raster accumulation 12,000 cells Attribute corresponding vector

11 Mismatch Between Raster and Vector Without Enforcement Non-enforced Enforced Can t attribute vector if data are mismatched

12 Why the DEMs and Stream Lines Do Not Match in Flat Valleys

13 DEM Production Process 1) Aircraft 2) Aerial photo 3) Stereo plotter 4) Map production 5) Scan and tag 6) LT4X LT4X, Infotec Development, Inc.

14 Original Contours and 10 m DEM Model 500 m LT4X Original 40 contours Blue box = 100 m x 100 m 2 m contours derived from 10 m DEM

15 Original Contours and 10 m DEM Model With Streams LT4X Original 40 contours 2 m contours derived from 10 m DEM

16 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

17 Why Not Use LiDAR? Site scale vs. landscape scale

18 Drainage Enforcement Algorithms 1) ANUDEM - ArcGIS 2) AGREE Arc Hydro Tools 3) IDDEA Forest Service

19 ANUDEM Implemented 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., A New Procedure for Gridding Elevation and Stream Line Data with Automatic Removal of Spurious Pits. Journal of Hydrology, 106:

20 AGREE Algorithm Implemented by Arc Hydro Tools Dewald, T., NHDPlus User Guide, U.S. EPA and USGS, April 29, 2008 Hellweger, F., AGREE DEM surface reconditioning system. Center for Research in Water Resources

21 Drainage Enforcement with AGREE Original Reconditioned Arcs must point downstream Smooth drop may modify watershed boundaries Uses trenching

22 IDDEA Method Inverse Distance Drainage Enforcement Algorithm 1) Grid stream lines 2) Generate Euclidean distance from all stream lines 3) Drop stream by constant value (e.g. 200 m) and 4) Invert distance, multiply by constant: (1/d) * ) Subtract result from original DEM Where c ij, 200, else e ij ((1 / d ij ) * 1000) c ij is a stream channel cell at raster location ij e ij is the elevation at ij d ij is the Euclidean distance at ij

23 1) Grid Stream Lines Vector to raster conversion

24 2) Euclidean Distance from Streams

25 3) Inverse Euclidean Distance (1/d) * Value decreases (unitless) Force constant drop (200 m) at stream channel Enforcement decreases away from the channel

26 DEM Minus Inverse Distance minus =

27 Profile Results Preserves relative topography and watershed boundaries

28 Run Flow Accumulation Nonenforced Enforced

29 Attributing Vectors Non-enforced Enforced Higher probability of accurately attributing vectors with the correct contributing area

30 Results Comparison Catchment Area Comparison y = x R² = Non-enforced Catchment Area (HA) IDDEA Catchment Area (HA)

31 Disadvantages of the IDDEA Method 1) Trenches the DEM 2) Meander bends smaller than cell size get cut off and reroute flow Trenching Cut-offs

32 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

33 Thank you

34 Selected References Buffington, John M., David R. Montgomery, and Harvey M. Greenberg, Basin-scale availability of salmonid spawning gravel as influenced by channel type and hydraulic roughness in mountain catchments. Canadian Journal of Fisheries and Aquatic Science 61: , doi: /F Crystal, Roger E., and Jason Underwood, Hydrologically Enhanced, High-Resolution DEMs. Geospatial Solutions, April 1, Hellweger, F., AGREE DEM surface reconditioning system. Center for Research in Water Resources, University of Texas at Austin. URL: Hutchinson, M.F., A New Procedure for Gridding Elevation and Stream Line Data with Automatic Removal of Spurious Pits. Journal of Hydrology, 106: Simley, Jeff, USGS National Hydrography Dataset Newsletter, vol. 3, no. 4, February URL: nhd.usgs.gov/newsletter_list.html. Simley, J.D., Carswell Jr., W.J., The National Map Hydrography: U.S. Geological Survey Fact Sheet , 4 p. USGS, Overview of DEM Production History, Historical DEM II Production Processes, September URL: USGS and EPA, NHDPlus User Guide, URL: April 29, 2008.