InVEST Analysis Lafarge Ecosystem Services Project

Avoided Reservoir Sedimentation

Results

LafargePresque Isle Quarry

Avoided Reservoir Sedimentation Loss

Estimates annual soil loss using Universal Soil Loss Equation

USLE = R x K x LS x C x P

R = Rainfall erosivity (the ability of rain to cause erosion)R = Rainfall erosivity (the ability of rain to cause erosion)K = Soil erodibility factor (soil susceptibility to raindrop impact and erosion) K = Soil erodibility factor (soil susceptibility to raindrop impact and erosion) LS = slope-length gradient factorLS = slope-length gradient factorC = Crop/vegetation and management factorC = Crop/vegetation and management factorP = Management practice factorP = Management practice factor

All figures are in metric tons.All figures are in metric tons.

InVEST Avoided Reservoir Sedimentation Model

• InVEST estimates the capacity of a land parcel to retain sediment using data on geomorphology, climate, vegetation and management practices using the USLE.

• Because no there is no InVEST model for mining – but only for hydropower – the only the total erosion figures and GIS maps were developed using InVEST. The valuation was done by hand, using data from the model and is described on slide 12.

Presque Isle Quarry

Two sub watersheds are associated with the site.

Calculations are based on sub watershed 1, including PIQ.

RKLS: Potential soil loss for bare soil with no vegetationRepresents the impacts of natural conditions, soil properties, climate, and slope

USLE: Potential soil lossTakes into account land use/land cover and cultivation practices

Sediment Retained by vegetation on Pixel Itself (Avoided Erosion)Equals RKLS minus USLE

Actual Sediment ExportedSediment load that will reach the stream from each pixel on the landscape

Total for PIQ Site: 0.94718 metric tons annually

Cumulative Sediment ExportedShows areas that contribute most to sediment loading within the watershed

Total Sediment Retained by Each Pixel on the LandscapeThis is the measure of the ecosystem service in biophysical terms

Total for PIQ site: 145,986 metric tons retained annually

Valuation Results

COSTS OF EROSION • Total erosion for entire watershed: 1.01734 metric tons/year • Total erosion for PIQ site: 0.94718 metric tons/year• Dredging costs: $US 16/cubic yard ($US 13.75/metric ton)** • Total erosion costs = total erosion x dredging costs

0.94718 tons X $13.75 = $US 13.02 (+ $5,000 survey fee)

Summary: assuming the InVEST model analysis is correct, only a small amount of sediment from the land in this watershed, including the quarry site, is exiting the site and reaching Lake Huron.

Source: US Army Corps of Engineers, 2009 “Contract Dredging Report Detroit District.” Note: Excludes survey fee of $US 2,000 to $US 5,000

**Assumes 1 cubic foot of top dredged soil weighs in 95 pounds. There are 27 cubic feet in a cubic yard. Hence, one cubic yard of top dredged soil is assumed to weighs 2565 pounds. There are 2000 pounds in a US ton and 2205 pounds in a metric ton. This equates into $12.48/US ton (16x2000/2565) or $13.75/metric ton (16x2205/2565).

Source: US Army Corps of Engineers, 2009 “Contract Dredging Report Detroit District.” Note: Excludes survey fee of $US 2,000 to $US 5,000

**Assumes 1 cubic foot of top dredged soil weighs in 95 pounds. There are 27 cubic feet in a cubic yard. Hence, one cubic yard of top dredged soil is assumed to weighs 2565 pounds. There are 2000 pounds in a US ton and 2205 pounds in a metric ton. This equates into $12.48/US ton (16x2000/2565) or $13.75/metric ton (16x2205/2565).

Valuation of Erosion Regulations Services PIQ site: $2,006,495 per year

Assumptions

-Use of default values for certain model inputs-Model can be calibrated more precisely with more detailed site info

-USLE method predicts sediment from sheet wash only-Gullies and stream-bank erosion/deposition are not included

Conclusions

-Allows managers to see which part of the landscape are providing the greatest value in terms of avoided sediment removal costs

-Relative retention/export values may be more useful than actual calculated estimates