EMISSION INVENTORY SOURCE CATEGORY

METHOD SUMMARY

This source category provides estimates of the fugitive dust emissions resulting from wind erosion of soil from unpaved roads. Using a windblown dust soil erosion equation, the emissions are estimated for each county based on the unpaved road mileage and local parameters that affect wind erosion.

ACTIVITY DATA SOURCE:  Activity data for the windblown dust emission factor equation is based on the acreage of erodible land. Using estimates of unpaved road mileage in each county and an average unpaved road width of 20 feet, the acres of unpaved roads in each county are computed. The unpaved road mileage was developed from the Caltrans, "Assembly of Statistical Reports" documents.

EMISSION FACTOR SOURCE:  The emission factor used for our estimates of geologic dust emissions from wind erosion of unpaved road material is based on an equation developed by the U.S. Department of Agriculture. The equation was originally derived in the 1960's to predict topsoil losses from agricultural fields. In 1974, the equation was modified by Midwest Research Institute to estimate the quantity of the eroded soil that is entrained to the air. This was done by simplifying the original equation somewhat, and scaling the results it provides to estimate the total particulate emissions suspended to the air.

TEMPORAL DATA:  Windblown dust emissions may occur 24 hours per day, seven days per week. Monthly activity varies by county and is based on the climatic factors for each county. In general, emissions are smaller when there is less wind and when there is more rain.

DATE OF THE LAST UPDATE:  August 1997

GROWTH PARAMETER:  Future projections of unpaved road windblown dust emissions are related to the miles of unpaved road. Because this information is not readily available, forecasts are based on population increases or other factors.

STATEWIDE EMISSIONS SUMMARY (1993 - ANNUAL AVERAGE TONS/DAY)

CES No.	TOG	CO	NOX	SOX	PM
83352	0.00	0.00	0.00	0.00	65.4

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This page last revised on November 12, 1997.

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