The Daily Erosion Project estimates sheet and rill erosion across agricultural areas in the Midwest on a daily basis using weather data, soil data, elevation models, and land use/management information. The project aims to further understanding of runoff and soil erosion dynamics and magnitudes. Erosion is estimated for over 2,000 12-digit hydrologic unit code watersheds in Iowa, Minnesota, and Nebraska using the Water Erosion Prediction Project model. Results are disseminated online. The project has found that erosion typically peaks in spring and is highest in years with heavy precipitation or snowmelt. Maintaining soil cover is important for reducing erosion during high runoff periods.

1. The Daily Erosion Project
Brian Gelder, Rick Cruse, Daryl Herzmann,
Claudette Sandoval-Green, John Laflen,
and Tim Sklenar, Iowa State University
David James, USDA ARS NLAE
1
Real Time Soil Erosion Monitoring and Inventory

2. Daily Erosion Project
• Our mission
– To further understanding of the dynamics and
magnitude of runoff and soil erosion through daily
estimation of these processes on agricultural areas
and dissemination of the estimates via the web
• Our project
– We estimate sheet and rill erosion across 2000+
Midwestern HUC12 watersheds every day
• Initially launched in 2003 for Iowa
• Currently expanding to surrounding states
– Fully coverage of Minnesota and Nebraska coming soon

3. NEXRAD
Precipitation
LiDAR
Elevation
gSSURGO
Soils
Field-scale
Land-use &
Management
Runoff
Detachment
Delivery
Soil Moisture

4. DEP Hillslope Profiles
• LiDAR-derived elevation models can
better predict water flow across the
landscape but…
– Doesn’t always flow
• Hydrologic enforcement cuts across
impediments to allow fully flowing
hydrologic regime
– Too many flowpaths for WEPP requires
random sampling
• Stratify HUC12s into sub-catchments
– TauDEM Peuker-Douglas method
constant drop stream analysis
– 125 sub-catchments per HUC12
• Select 1 agricultural flowpath per sub-
catchment
– No other land uses currently
• Respects impediments to flow;
terraces, roads, non-Ag land

5. Field polygons (> 15 ac) have
• Majority land cover for last
six years
– Assigned to a rotation to
predict current crop
• A tillage class derived from
satellite imagery
+
DEP - Land Use & Management
2013
20112010
2012
20152014

6. • USDA NRCS gSSURGO 10m soil
map raster
• Custom attribute extraction
– Texture, Organic matter, CEC
• Current FY data
Soils Data

7. DEP Weather
• NEXRAD radar data
– 5 minute, 1 x 1 km rainfall
• 25x25 km wind, temp, and
solar radiation
• Most code for running DEP is on github
– https://github.com/akrherz/dep
– At 1:30 AM a program starts checking for rainfall
input availability

8. What’s It Like In the Field?

9. Flowpaths & Land Use
FB070802030106
GenLU
Corn/Soybeans
C/S with Continuous Corn
Pasture
Conservation Rotation
Mixed Agriculture
Continuous Corn
Extended Rotation
Flood-prone Cropland
Forest
LT 15ac
UnAssigned
Water/wetland

10. Flowpath Parameterization
Land Use Soils

11. DEP Hillslope Profiles
• WEPP OFEs break at Land-use and Soils boundaries
• Slope estimated for each OFE from DEM and flowpath length
OFE 2
OFE 3
OFE 1
OFE 4

12. DEP Map Interface
Search for HUC12, decrease
layer transparency, increase
layer transparency, download
as .shp, shrink window, expand
window
Toggle single/multi day search
range and date entry(s)
Zoom to a state, zoom in/out
(+/-), zoom to extent (E) Toggle which variable to view
Toggle which layers to view
Toggle how to view detailed data
Static web link

13. How Fast Are They Eroding?

14. How Fast Are They Eroding?

15. How Fast Are They Eroding?

16. How Fast Are They Eroding?

17. HUC12 Mean Slope (%)

18. Daily Erosion Project Trends

19. Daily Erosion Project Trends

20. Daily Erosion Project Trends

21. Daily Erosion Project Trends
• It's not hard to believe…
– Precipitation drives runoff!
• Most years precipitation peaks in May
– Erosion declines more rapidly than precipitation due to rapidly
emerging vegetation that protects soil
• More runoff in late winter than precipitation
– Snowmelt runoff from snowy winters
» 2008, 2010, 2011, 2013, 2016
• 2015 had wet fall
– Double precipitation and runoff peaks

22. Daily Erosion Project Trends

23. Daily Erosion Project Trends

24. Daily Erosion Project Trends
• It's not hard to believe…
– Runoff drives erosion!
• Erosion is not common during winter or late summer
– Winter has frozen surface soils
» Typically not much rain with frozen subsurface
– Summer has excellent crop canopy

25. Daily Erosion Project Trends
• Midwestern water erosion typically occurs
during spring field preparation
– Greater slopes enable greater delivery
• Management practices that maintain cover and
reduce runoff during these time periods will be
most effective
– Low tillage intensity
– Cover crops
– Grass waterways
– Tile drainage

26. DEP Questions?
• Acknowledgements:
– ISU Agronomy Department Endowment
– IDEP1, IDEP2, DEP
– USDA Agricultural Research Service NLAE
– IDEP1, IDEP2, DEP
– USDA NRCS
– Preliminary Management Work, ACPF Expansion
– Environmental Defense Fund
– Preliminary ACPF Work
– Iowa DOT and Iowa Institute for Hydraulic Research (IIHR)
– DEM Enforcement
– North Central Regional Water Network
– ACPF Expansion
DEP Web Pages
http://dailyerosion.org/map/
http://dailyerosion.org/

27. 1647 HUC12 Watersheds in Iowa
54 HUC8 whole or partial watersheds (blue lines)

28. DEP Sampling Scheme
HUC12
(Each HUC12 approx. 10000 ha)
HUC12 Sub-catchment (Stratified sample)
(Each sub-catchment approx. 100 ha)
(Approximately 125 flowpaths per HUC12)
Flowpath (1 Random sample w/i sub-catchment)
(Approximately 10-100 m long)
(Only in dispersed flow)

29. HUC12s & Sub-catchments
HUC 12 Boundary
(approx. 10000 ha)
Subcatchment
Boundary
(approx. 100 ha)
Subcatchments are defined by the
Peuker-Douglas constant drop stream
Algorithm in TAU-DEM

30. Sub-catchments & Flowpaths
Subcatchment Boundary
Flowpath
(Not modeled)
Flowpath
(Modeled)
1 random flowpath per subcatchment
Must be on agricultural land
Approximately 10-100 m long
Only modeled in sheet/rill flow

31. DEP Accuracy
• Assessing accuracy of DEP is difficult as no
truly comparable dataset exists
– Monitoring at 300,000+ sites would be expensive
– Most comparable is from the USDA Natural
Resources Inventory (NRI) every 5 years
• Results only available at state level
– Another comparison was made to see if sloping
land fraction was correlated with erosion at HUC8
level
• Yes, it is – that's a good thing

32. Iowa NRI vs. DEP
0
2
4
6
8
10
12
1980 1985 1990 1995 2000 2005 2010 2015 2020
Erosion(tonac-1yr-1)
NRI vs. DEP Sheet and Rill Estimates
NRI DEP
*
* DEP Mean

33. DEP Questions?
• Acknowledgements:
– Iowa Nutrient Research Center
– Cover Crops/Residue Cover Mapping
– Conservation Practice Mapping
– Stacked Scenarios for Phosphorus
– Union of Concerned Scientists
– Erosion Scenarios
– Minnesota BWSR and DNR
– ACPF/DEP Expansion
– US Department of Housing and Urban Development FEMA
– Flood Reduction Scenarios
– Nebraska NRCS
– DEM Enforcement-ACPF/DEP Expansion
Over $1.7 Million in
External Funding

34. Flowpath Parameterization
• For each watershed an overlay is conducted to
correlate all WEPP inputs other than climate
– XY location (later used to find climate)
– Flowpath number
– Elevation
– Flowpath length
– Crop rotation
– Tillage management
– Soils
• Slope is figured as elevation change over distance

35. Post Fall Residue Polygons NDTI = Band 5 – Band 7
Band 5 + Band 7
DEP Management – Residue Cover

36. USDA/ARS Agricultural Conservation Planning Framework
(ACPF) and the Daily Erosion Project
• The DEMs, crop rotation, and soils data used in the Daily Erosion
Project are derived from the Agricultural Conservation Planning
Framework (ACPF) database
– Tomer et al., USDA/ARS National Laboratory for Agriculture and the Environment (NLAE)
• ACPF database combines with the ACPF Toolbox to do field-level
conservation planning
– Saturated Buffers
– Riparian Functional Analysis
– Nutrient Removal Wetlands
– WASCOBs
– Contour Buffer Strips
• The ACPF (part of USA only) is available on the North Central Region
Water Network website at http://northcentralwater.org/acpf/