Sediment Retention model Invest 2.2.1 Sediment Retention model Yonas Ghile

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

What are Ecosystem Services?

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

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

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

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?

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?

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

Valuation Time Loading Critical Loading

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

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

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

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

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

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

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

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

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

Hands-on Session Run the soil loss model

Hands-on Session Run the valuation model

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

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

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

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

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

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

How Does it Work?... 𝐿𝑆= 𝑓𝑙𝑜𝑤𝑎𝑐𝑐∗𝑐𝑒𝑙𝑙𝑠𝑖𝑧𝑒 22.13 𝑛𝑛 * sin (𝑠𝑙𝑜𝑝𝑒∗0.01745) 0.09 1.4 ∗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

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

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

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