1. Sediment Retention model
Invest 2.2.1
Sediment Retention model
Yonas Ghile

2. Talk Overview Why care about ecosystem services? InVEST
Sediment Retention Model
Hands-on Exercise
Case study

3. What are Ecosystem Services?

4. InVEST: Science in a Simple Tool
Integrated Valuation of Ecosystem Services and Tradeoffs

5. InVEST Attributes Multiple services Spatially explicit
Production functions
Evaluate change
Biophysical & monetary
Open source
Tier 1
Tier 2
Tier 3
Models
Data
Simple
Complex
Tier 0

6. Why sediment retention model?
Soil erosion and sediment can cause:
Decrease in agricultural productivity,
Degradation of fish habitat and aquatic life,
Risk of structural failures
water quality degradation.
Increase maintenance cost

7. Questions you get answers
Where are the Sediment sources?
Where are the Sediment retention areas?
How much is retained?
What is the Value of this retention?

8. Informs Policy Makers to
Focus protection on areas that retain the most and pollute the least
Design management practices that lead to maximize retention
Create payment programs to get most return on investment (with tier2)
Identify places where other economic activities will conflict with erosion control
How much costs can be avoided under future management or conservation plans?

9. Sediment Retention Model
Conservation
factor
Slope
Erosivity
Soil Erodibility
Crop factor
Sediment loads

10. Valuation
Time
Loading
Critical Loading

11. Strengths Uses readily available and minimum data.
Simple, applicable and spatially explicit
Link the biophysical functions to economic values
Values each parcel on the landscape

12. Limitations Predicts erosion from sheet wash alone
Considers only individual effect of each variable
Relies on retention and filtration efficiency values for each LULC
Neglects the role of topography, soil, climate in the retention processes
Accuracy limited in mountainous areas

13. Model Calibration and Testing
Sensitivity Analysis to identify most sensitive parameters
Model Calibration using long term average actual data
Find USLE parameters within acceptable ranges
Validate Model by conducting comparisons with observed data or other model output

14. Hainan Island, China
Simulated vs Observed Soil loss (103 t)

15. Hainan Island, China RNF 2008 NRPE IEM Soil Loss (103 ton) Nandujiang
400
300
200
100
Soil Loss (103 ton)
Nandujiang
Wanquanhe
Changhuajiang

16. Scenarios for Mine Expansion in Columbia
Current
Mines
Permits
Granted
Pending
All possible
permits

17. Mining in Columbia Sediment Load (t/ha/yr) Permits Granted
Permits Pending
All possible Permits

18. Mining in Columbia High Impact Zones should avoided Permits Granted
Permits Pending
All possible Permits

19. Coming up soon in InVEST
Sediment delivery ratio
Gully and bank erosion (tier 0)
Dam retention
Multiflow algorithm
Will run faster
Improved Length Slope equation
West Coast
East Coast
Belize
Colombia
Mexico
Ecuador
Amazon Basin
Tanzania
Indonesia

20. Hands-on Session
Run the soil loss model

21. Hands-on Session
Run the valuation model

22. Hands-on Session
Think about how you would use the Sediment Retention Model in your work?

23. How Does it Work? Natural Characteristics:
R – Rainfall Erossivity
K – Soil Erodibility
LS – slope-length factor
Land Use Land Cover Management Practices:
C – conservation factor
P – Practice factor
this is the big idea. how it is meant to work.
key things:
multiple services
looking into future
scenarios driven by upcoming policy choices, of interest to stakeholders

24. Biophysical Inputs Land Use/Land Cover Streams Watershed Areas Slope
Vegetation retention, land practice and management
Streams
Used to determine where sediment flows to
Watershed Areas
Main and sub for point of interest and water quality analysis
Slope
Digital elevation model, slope threshold
Erosivity
Based on intensity and kinetic energy of rainfall
Reservoir Features
Dead volume, lifetime of reservoir, allowed load
Erodibility
Soil detachment and transport potential due to rainfall

25. Biophysical Outputs Potential Soil loss Sediment Exported
Calculated from USLE per sub-watershed
Sediment Exported
Calculated per sub-watershed
Used in valuation
Sediment Retained
Calculated per sub-watershed

26. Valuations Valuation Inputs Valuation Outputs Watershed Areas
Main and sub for point of interest and water quality analysis
Value of Sediment Removal for Dredging
Sediment Exported
From biophysical analysis
Value of Sediment Removal for Water Quality
Sediment Retained
From biophysical analysis
Sediment Valuation
Reservoir dredging costs

27. How Does it Work?... Data inputs for Soil Erodibility
Percent Silt, %Slt
Percent Very Fine Sand, %VFS
Percent Clay, %Cly
Percent Organic Matter, %OM
Soil Structure Code, SC
Profile Permeability, PP
this is the big idea. how it is meant to work.
key things:
multiple services
looking into future
scenarios driven by upcoming policy choices, of interest to stakeholders

28. How Does it Work?...
𝐿𝑆= 𝑓𝑙𝑜𝑤𝑎𝑐𝑐∗𝑐𝑒𝑙𝑙𝑠𝑖𝑧𝑒 𝑛𝑛 * sin (𝑠𝑙𝑜𝑝𝑒∗ ) ∗1.6
For low slopes
For high slopes
𝐿𝑆=0.08∗ 𝜆 0.35 ∗ 𝑠𝑙𝑜𝑝𝑒 0.6
LS: Slope length factor
Original LS was calculated from plots of 72.6 feet long and 9% slope
The steeper and longer the field the higher is the risk of erosion.
this is the big idea. how it is meant to work.
key things:
multiple services
looking into future
scenarios driven by upcoming policy choices, of interest to stakeholders

29. How Does it Work?... Hydraulic connectivity model
this is the big idea. how it is meant to work.
key things:
multiple services
looking into future
scenarios driven by upcoming policy choices, of interest to stakeholders

30. How Does it Work?... 1. 𝑆_𝑟𝑒𝑡𝑎𝑖𝑛 𝑥 = 𝑅.𝐾.𝐿𝑆.𝐶.𝑃 −(𝑅.𝐾.𝐿𝑆)
1. 𝑆_𝑟𝑒𝑡𝑎𝑖𝑛 𝑥 = 𝑅.𝐾.𝐿𝑆.𝐶.𝑃 −(𝑅.𝐾.𝐿𝑆)
2. Removal of sediments by vegetation along the flowpaths is
calculated as follows
this is the big idea. how it is meant to work.
key things:
multiple services
looking into future
scenarios driven by upcoming policy choices, of interest to stakeholders

31. How Does it Work?... 𝑃𝑉𝑆𝑅 𝑥 = 𝑡=0 𝑇−1 𝑇𝑜𝑡_𝑟𝑒𝑡𝑎𝑖𝑛 𝑥 ∗𝑀𝐶 1+𝑟 𝑡
Sediment Yield is defined as the potential soil loss from terrestrial sources that might get into a water body
Value of removed sediment at pixel x:
corn
forest
wheat
Stream
Cumulative Sediment Yield
this is the big idea. how it is meant to work.
key things:
multiple services
looking into future
scenarios driven by upcoming policy choices, of interest to stakeholders
𝑃𝑉𝑆𝑅 𝑥 = 𝑡=0 𝑇−1 𝑇𝑜𝑡_𝑟𝑒𝑡𝑎𝑖𝑛 𝑥 ∗𝑀𝐶 1+𝑟 𝑡