This document summarizes a project that aimed to reduce sediment and nutrient export from watersheds in Kansas through targeted BMP implementation. The project measured the success of prior BMPs, targeted new ephemeral gully BMPs through mapping and modeling, educated producers and stakeholders, and expanded higher education opportunities. Key findings included identifying the most vulnerable crop fields, accurately locating and measuring ephemeral gullies, understanding phosphorus losses from different erosion processes, and increasing awareness of conservation practices. The project produced peer-reviewed publications, educated students, and established connections with local stakeholders.

1. Measuring Success of Targeted BMP
Implementation, and Getting Smarter about
Ephemeral Gully Sediment and Nutrient
Sources and BMPs
A. Sheshukov, R. Graber, N. Nelson, T. Keane, D. Devlin
Kansas State University
2016 USDA-NIFA Project Directors Meeting
Washington, DC
Project 2011-51130-31128

2. 2
Sedimentation and Soil Erosion
• Contribution of EG erosion
– U.S.: 17 to 73%
– Central Kansas: 42%
• EG erosion rates (in kg/m2/yr)
– U.S.: 0.27 to 2.87
(1.1 to 11.9 t/ac/yr)

3. 3
Study Area
• Little Arkansas River watershed (HUC-8
11030012)
– 3,600 km2 in south-central Kansas
– Five targeted HUC-12 subwatersheds
• Agricultural watershed
– 68% cropland, 19% grazing land
• 52% of stream segments required TMDLs
– Water quality concerns include bacteria,
nutrients, sediment, and pesticides
(atrazine herbicide)
• Drinking water source for city of Wichita
and numerous smaller cities and towns
• Source for aquifer recharge

4. 4
Project Goal and Objectives
Goal: Demonstrate that sediment & nutrient export
from a watershed can be reduced by planned BMP
implementation.
Objective 1 — Measure Water-Quality Success of Installed BMPs.
Objective 2 — Target New Ephemeral Gully BMPs.
Objective 3 — Educate Producers and Stakeholders.
Objective 4 — Expand Higher Education.

5. 5
• Data collection
– 1m LiDAR DEM
– Sub-CLU LULC layer
– EG CLU-based map
– 12 stream monitoring sites
• Annual surveys
– 2010-15: BMP, Tillage, Crop
surveys (409 fields – 29,335
acres)
– 2012-14: EG survey
No EG;
Grass waterway
EG observed
Objective 1: Water-Quality Success of Prior BMPs
Watershed Assessment

6. 6
KANSAS
Running Turkey
Dry Turkey

7. 7
Sheet & Rill Erosion
• SWAT model – Field –scale results
– Top 10% fields produce 71.2% TSS yields
– Top 10% fields occupy 38.3% area
• Running Turkey (undisturbed)
– Area of Med-High S&R erosion – 607 ha
– Average Med-High S&R erosion load – 4.4 tn/ha
• Dry Turkey (disturbed)
– Area of Med-High S&R erosion – 757 ha
– Average Med-High S&R erosion load – 4.2 tn/ha

8. 8
Objective 2: Target Ephemeral Gully BMPs
Location and Length of Ephemeral Gullies
• Topographic Index models
– 2433 catchments in Running Turkey
– 2151 catchments in Dry Turkey
– 38 grassed waterways in Running Turkey
– 25.1% fields had ephemeral gullies
• Compared predicted and observed gully occurrence in
each catchment
• Error matrix approach for location analysis
• NSE and RMSE for length analysis
• Drainage density error for headwater and mainstem
gullies

9. 9
Six Topographic Index models
9
1. T = SAs Slope Area Index (SA)
2. T = SAs
b Slope Area Power Index (SAP)
3. T = SAPLANC Compound TI (CTI)
4. T = ln(As/S) Topographic Wetness Index (TWI)
5. T = 3.3nLS-1/2 Kinematic Wave (nLS) Model
6. T = 3.3nLτc
-1S-1/2 Modified Kinematic Wave
(nLSCSS) Model

10. 10
Topographic Index Analysis
Kernel Density
Estimate
Cohen’s Kappa

11. 11
Soil Erosion Risk Maps
Parameter Dry Turkey Running Turkey
Area (ha) 9,525 9,137
Land under agriculture (%) 77 % 79 %
Total Cropland fields 584 476
Number of Cropland fields with EGs 115 109
Total EG length on fields (m) 8,543 22,600
Area of med-high S&R erosion (ha) 757 607
Ave med-high S&R erosion load (tn/ha) 4.2 4.4

12. 12
Mgmt
No-till
(>10 yrs)
Crop Sorghum
Soil
Silty Clay
Loam
Slope 1÷3 %
Area 1/8 sec
No-Till
Mgmt
Conv-till
(>10 yrs)
Crop Wheat
Soil
Clay
Loam
Slope 3÷7 %
Area 5.2 ha
Tilled
Objective 2: Target Ephemeral Gully BMPs
Gully Surveying

13. 1313
No-Till Tilled

14. 1414
• Gully channels experienced fluctuations of erosion and deposition
• Gully channel was net depositional, but smaller headwater gullies grew
• Greatest rates of deposition at confluence of main channels, but heavy rains of spring
2015 flushed sediment
• Statistics showed factors other than rainfall depth, intensity, etc. can be important

15. 15
Field Monitoring
• 3.2 acre catchment
– No-till last 10 years
– No contour farming
– Wheat-corn-sorghum rotation
– Crete silt loam soil, 1-3% slope

16. 16
Field Study of Gully Erosion
7/11/2013
7/11/2014
9/15/2013
• EG vs. S-R erosion rates:
– 2013 EG Headcut: 122 kg (0.1 tn/ha)
– 2013 Sheet-Rill: 1,560 kg (1.3 tn/ha)
– 2014 EG Headcut: 274 kg (0.23 tn/ha)
– 2014 Sheet-Rill: 1,344 kg (1.1 tn/ha)
2013
2014
• Antecedent soil moisture prior to event extremely important
• No-till needs to be complemented with other conservation
practices (Contour farming, terraces, cover crops)

17. 17
Field vs. Headcut vs. Channel Erosion
• Sheet-Rill erosion by WEPP
• Headcut erosion by pin-frame
• Channel erosion by pin-frame and interpolation
17
-1.00
-0.50
0.00
0.50
1.00
1.50
2.00
2.50
7/11/2013
8/6/2013
8/21/2013
9/19/2013
10/17/2013
11/7/2013
4/9/2014
5/9/2014
5/31/2014
6/27/2014
7/11/2014
8/5/2014
8/12/2014
9/15/2014
Soilloss(tn)
Sheet-Rill Headcut Channel
Sheet-Rill Headcut Channel
2013 1.29 0.08 0.09
2014 3.06 0.18 -0.08
Total (tn/ha) 4.35 0.26 0.01

18. 18
Numerical Model for Channel
Development
Hard pan
Soil of higher drainage rate
Symmetry line
𝜕𝜃
𝜕𝑡
=
𝜕
𝜕𝑧
𝐾 ℎ
𝑑ℎ
𝑑𝑧
−
𝜕𝐾 ℎ
𝜕𝑧
+
𝜕
𝜕𝑥
𝐾 ℎ
𝑑ℎ
𝑑𝑥
Moving boundary

19. 19
Soil water pressure:
initially dry soil vs. wet soil
hinitial = - 100 cm hinitial = - 10 cm

20. 20
Soil water pressure:
initially dry soil vs. wet soil
hinitial = - 100 cm hinitial = - 10 cm

21. 21
The dynamics of channel erosion
hinitial = - 100 cm hinitial = - 10 cm
Constant 𝜏c (𝜏c = 𝜏 𝑐
0) Variable 𝜏c (𝜏c = 𝜏 𝑐
0 𝛷 𝑖 𝑛 )
Dry soil
Variable 𝜏c (𝜏c = 𝜏 𝑐
0 𝛷 𝑖 𝑛 )
Wet soil
hinitial = - 100 cm

22. 22
Channel geometry
at time = 160 min
hinitial = - 100 cm hinitial = - 10 cm
Constant 𝜏c (𝜏c = 𝜏 𝑐
0) Variable 𝜏c (𝜏c = 𝜏 𝑐
0 𝛷 𝑖 𝑛 )
Dry soil
Variable 𝜏c (𝜏c = 𝜏 𝑐
0 𝛷 𝑖 𝑛 )
Wet soil
hinitial = - 100 cm

23. 23
Channel erosion rates

24. 24
Objective 2: Target New Ephemeral Gully BMPs
Soil P Content and P Sorption on EG Field
Wedel
(no-till, sorghum)
Goering
(conv till, wheat)
Schmidt
(no-till, wheat)
• Equilibrium P concentration (EPC0) drops quickly with depth
• P desorbing from sheet-rill and adsorbing on to EG sediments
• EGs contributed less P compared to topsoil sediment due to P stratification
• Enrichment of surface soils eroded through sheet and rill erosion.

25. 25
P Loss with Reduction of EG Erosion
• Reducing EG erosion could decrease total P loss over 90%
• However dissolved P loss could increase up to 6 times
• EG BMPs should be combined with P management BMPs to fully control
dissolved P loss

26. 26
Objective 3: Educate Producers and
Stakeholders
1. Quarterly WRAPS SLT meetings and
presentations (2011-2016)
2. Three field days on soil health and
ephemeral gullies (2014-2016)
3. JET workshop (2015)
4. Continuous stream monitoring network
5. Newspaper and radio presence
6. Numerous updates/reports to state &
local groups (LA BAC, SWAB, Equus Beds
GMD, CD’s, etc.)

27. 27
Objectives 4: Expand Higher Education
• Trained graduate students
– 2 PhD Students
– 3 MS students
– Several undergrad students
• Watershed and Fluvial Ecosystem Resources (WaFER) Graduate
Certificate Program
– Conducted employer survey to determine target professionals and jobs
– Multi-disciplinary course content with involvement of three colleges
– Core and specialization courses
– Presently, curriculum approved but Global Campus recommended

28. 28
Products and Outcomes
• Products
– SWAT model and EG-related materials
– S-R erosion rates at most vulnerable fields
– Locations and lengths of EGs in two HUC-12 watersheds
– P-loss estimates for EG vs. S-R erosion
– 6 peer-reviewed publications (2 in review)
– 16 conference presentations
– 3 MS theses (Coover, Stout, Sekaluvu); 1+1 PhD dissertation (Burke,
Karimov)
• Outcomes
– Established connection with local SLT
– Increased awareness among growers including utilizing nonstructural
BMP’s such as cover crops
– 3 watershed field days, workshop on Jet Erosion Test
– Continuous stream sampling and field annual surveying
– Off-site BMP Implementation Program approved by the city of Wichita
– 2 PhD and 3 MS Students
– WaFER Graduate Certificate program

29. 29
Thank You!
• Acknowledgements
– Graduate students:
• V. Karimov, K. Burke, J. Coover, L. Sekaluvu, B. Stout
– Watershed stakeholders and Rick Schlender
– Owners of four crop fields
– USDA-NIFA NIWQP for funding