72nd SWCS International Annual Conference July 30-August 2, 2017 Madison, WI

1. Soil Vulnerability Index (SVI) Case Study: Delta Water
Management Research Unit in Northeast Arkansas
Authors
Sapana Lohani, Post-Doc, University of Missouri, Columbia, MO
Claire Baffaut, Research Hydrologist, USDA-ARS, Columbia, MO
Allen Thompson, Assoc. Prof., Biological Engineering Dept., Univ. of Missouri, Columbia, MO
Niroj Aryal, ORISE Post-Doctoral Fellow, DWMRU (Presenter)
Michele L. Reba, Research Hydrologist, USDA-ARS, DWMRU, Jonesboro, AR

2. Study Sites

3. SVI Results
Soil Runoff Potential Soil Leaching Potential

4. Soil Runoff Potential: Slope <0.5%; No HSG-B
Soil runoff
potential
HSG-A HSG-B HSG-C HSG-D
Low All acres Slope < 4 Slope < 2 Slope < 2
K-factor < 0.28
Moderate None 4 ≤ Slope ≤ 6
K-factor < 0.32
2 ≤ Slope ≤ 6
K-factor < 0.28
Slope < 2
K-factor ≥ 0.28
Moderately
High
None 4 ≤ Slope ≤ 6
K-factor ≥ 0.32
2 ≤ Slope ≤ 6
K- factor ≥ 0.28
2 ≤ Slope ≤ 4
High None Slope > 6 Slope > 6 Slope > 4

5. Soil Runoff Potential: Slope
• Slope sets runoff potential to low or moderate depending on HSG and k-factor
• HSG and K are determining factors, but K is on play only when HSG is D
Soil runoff
potential
HSG-A HSG-B HSG-C HSG-D
Low All acres Slope < 2 Slope < 2
K-factor < 0.28
Moderate Slope < 2
K-factor ≥ 0.28

6. Soil Leaching Potential: No organic soils, HSG-B, and slope
<0.5%
Soil leaching
potential
HSG-A HSG-B HSG-C HSG-D
Low None None None All acres except
organic soils
Moderate None Slope ≤ 12 and
K-factor ≥ 0.24
or slope > 12
All acres
except
organic soils
None
Moderately High Slope > 12 3 ≤ Slope ≤ 12
K-factor < 0.24
None None
High Slope ≤ 12 or
organic soils
Slope < 3 and
K-factor < 0.24
or organic soils
All organic
soils
All organic soils

7. Soil Leaching Potential: No organic soils and slope <0.5%
• Possible leaching potential is low in D, medium in B and C and high in A
• Hydrologic Soil Group is the only factor
Soil leaching
potential
HSG-A HSG-B HSG-C HSG-D
Low All acres
Moderate All acres
Moderately High
High All acres

8. SVI Results
Soil Runoff Potential
Soil Leaching Potential
66.6%
0.49
33.4%
0.24
85%
0.24

9. Discussion
• How to differentiate low slope fields?
• Any more variable to assist HSG, when HSGs are similar?
• How to differentiate C/D vs D or C?
• How does artificial drainage affect runoff potential?