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Dust Definition: Saguaro West Case Study

Julia Lester WRAP DEJF Meeting

ENVIRON International November 16, 2005

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BACKGROUND

• WRAP’s Dust Emissions Joint Forum (DEJF) developed a draft definition of dust to discriminate between natural and anthropogenic sources of dust

• WRAP sought a feasibility assessment of draft definition– Draft Feasibility Assessment Report with Protocol

(May)– Case studies as examples of Protocol application– Recommended revisions of the draft dust definition,

if necessary– Implementation support, as resources permit

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Case Studies

• Several potential case studies identified• Based on latest Causes of Dust results, COHA analyses,

other WRAP programs, 2 case studies identified through discussion with WRAP staff and the DEJF:– Saguaro West (SAWE) in Pima County Arizona

• CoD / CoHA: 123 dust days with soil / coarse mass significant contributors to 20% worst visibility days

– Salt Creek Wilderness in New Mexico• Interaction with the New Mexico SIP Pilot Project

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Dust Definition Categories

• Feasibility Assessment Proposed 3 Categories

1.Anthropogenic

2.Natural (some sources currently not inventoried)

3.Mixed: Natural sources that can be anthropogenically influenced

- WRAP interested in partitioning existing dust emission estimates for this category (natural vs. anthropogenic)

- Identified data/method resources may be used for new or revised inventories for some sources

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Feasibility Assessment Protocol

1. Identify the purpose and goals of the analysis

2. Conceptual Model and rank order the dust sources in the project area by chosen criteria

3. Identify major Category 3 sources

4. Identify controls/mitigations, if desired

5. For major Category 3 contributors, are existing methods/databases available to characterize, estimate, and/or partition the emissions?

6. If not, can the necessary methods/databases be developed and at what cost?

If the answers to 5 and/or are yes, definition can be implemented

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Step 1: Saguaro West (SAWE) Study Purpose and Goals

• Pilot-scale feasibility assessment (conserve resources for Salt Creek Wilderness assessment)

Item SAWE Case Study Full-scale Study

Analysis area 135 to 225 quadrant, 20-km radius

Full 360 area with 20km or more radius

Resource identification

As in full study All

Dust source identification

Limited Comprehensive, GIS spatially-resolved, long-range sources assessed

Dust source characterization

Identify models / data for most significant source

Identify models / data for all significant sources

Ems Inventory Most significant All significant sources

Inv. partitioning Most significant with available data

All significant Cat. 3 sources

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Step 2: SAWE Study Conceptual Model

• Conceptual Model Elements– Geographic setting– PM and visibility setting

• Focus of this study is worst dust days for visibility impairment

• Latest CoD and CoHA results– Geological, topical, ecological, and climatological

setting– Land use setting– Summary, including significance threshold

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Conceptual Model: CoD Information

Source: CoD Report, DRI

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Conceptual Model: SAWE CoHA Information

Source: CoHA Report, DRI

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Conceptual Model: Land Use

Source: CoHA Report, DRI

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Conceptual Model: Land Use

Agricultural crops 5 to 10 km SW of Saguaro West

• Focus area dominated by open shrub/grass lands, with small areas of agricultural row crops and urban uses (Mining activities, if study area expanded)

• Potential grazing areas not yet identified

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Conceptual Model: Summary

• Based on the latest CoD results, case study will focus on worst dust days related to local dust sources– 135 to 225 quadrant focus, radius 20 km (local

sources)– April through July have greater CM and fine

soil contributions, so seasonal emissions will be reported if they exist

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Step 2 (cont): Initial Ranking of Sources

Table 1. Dust sources likely to affect SAWE

Dust Source Type Description

CategoryRelevance

(1-5, 1 being most relevant)

Notes

Agriculture Crops Livestock-grazed Rangeland

1 2~10-km2 area of cropland 5-10 km SW of Saguaro West

Construction and demolitionResidential area and developments

1 4Various scatted residential / light industrial development in SE area of Focus Area

Paved and unpaved roadways, including irrigation canal roads

1 3

Identifying data resources (e.g. 50-m wide irrigation canal running NW to SE from 0.5 km S of SAWE

Foot trails Hiking trail system

1 5

Surface mining disturbance:4 quarries, large copper mine SE of SAWE

1 4 (or 2*) 35 to 50 km away

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Step 2: Initial Ranking of Sources (cont.)

Table 1 continued. Dust sources likely to affect SAWE

Dust Source Type Description

CategoryRelevance

(1-5, 1 being most relevant)

Notes

Natural landslides and rockslides 2 5Landslide incidence low (< 1.5% of area)

Extraterrestrial material and impacts 2 5

Wildlife movement Large mammals (cows, sheep,

mule deer, white-tailed deer, pronghorn, peccary)

3Unknown at this

time

All areas except urban areas suitable for wildlife

Animal burrowing 12 species of carnivores (e.g.,

coyotes, foxes, bobcats), 3 species of insectivores (shrews), 4 species of lagomorphs (rabbits), 32 species of rodents (gophers, rats, mice, etc.)

3Unknown, but

may be significant

All areas except urban areas suitable for wildlife

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Step 2: Initial Ranking of Sources (cont.)Table 1 continued. Dust sources likely to affect Saguaro National Park.

Dust Source Type Description

CategoryRelevance

(1-5, 1 being most relevant)

Notes

Windblown from undeveloped lands (undisturbed or previously disturbed)

3 1

Emission from shrublands probably the highest – need to identify past and current rangelands, if any

Areas burned by fires 3 5Reviewing Fire Forum resources

Exposed beds of dry riverbeds and drainagesBrawley Wash and tributariesSanta Cruz River and tributaries

3 4

Limited amount of surface water may be diverted for anthropogenic use. Intermittent drainages. Focus Area is covered in small dry intermittent drainages.

Windblown PM from sources created by natural events over 12 months previously

3 5Reviewing Arizona NEAPs

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• Most relevant: Windblown dust (Category 3)• Next most relevant: Agriculture (Category 1)

– If the study area was extended to 50 km, surface mining would also be included at this level

• Emissions from animal movement and burrowing, or the effects of these activities on windblown dust emissions, (Category 3)– relevance cannot be assessed without further

investigation

• Results of Step 5 may indicate the need to re-order the source rankings

Step 2/3: Initial Ranking Summary

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Step 5: Resource Availability for Category 3 Sources

• For major Category 3 contributors, are resources available to characterize, estimate, and/or partition the emissions?– Data and Model Resource Identification– Dust source characterization– Site-specific dust emission estimates– Emission partitioning

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Step 5: Resource Identification

Southwest Regional GAP Analysis Project Attribution of Haze (AoH) data and analyses: www.wrapair.org/forums/aoh/ars1/report.html

Google Earth (aerials) WRAP Technical Support Syatem (under development) www.wrapair.org/forums/aoh/TSS/index.html

National Resources Inventory WRAP Windblown Dust Emission Model

Land Condition Index NRCS PLANTS Database

Soil Data Mart: Soil Survey Geographic (SSURGO) database

Wildlife Exposure Factors Handbook

COHA data: www.coha.dri.edu/ Smithsonian National Museum North American Mammals Database

Arizona Meteorological Network (AZMET) Grazing Land Applications Software (GLA)

Hydrometeorological Networks in the United States (JOSS)

Cumulative Index for the Mammalian Species

• 32 data/model resources identified for study area (many are in the process of development or revision)

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Step 5: Dust Source Characterization, Emission Estimation, and Partitioning

• Most significant SAWE source (windblown dust) resource analysis

Source Category

Availability of Emissions Data

Availability of Partitioning Data

Windblown Dust from Row Crops (Category 1)

High: Generate via WRAP Windblown Dust Emission Model

Not required for Category 1 Dust Source

Windblown Dust from Shrublands and Grasslands (Category 3)

High: Generate via WRAP Windblown Dust Emission Model

Data on vegetation coverage may be available. Vegetation coverage in grazed areas or otherwise humanly disturbed areas could be compared with vegetation coverage in nearby ungrazed reference areas

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Step 5: Dust Source Characterization, Emission Estimation, and Partitioning

• Potentially major SAWE source (animal movement, impact of burrowing animals) resource analysis

Source Category

Availability of Emissions Data

Availability of Partitioning Data

Large mammal movements (Category 3)

Not available Identification of legal grazing lands may be possible

Burrowing Animal Impacts(Category 3)

Direct or indirect emissions estimates are not available

Emissions may be higher than assumed through traditional erodibility metrics (see next column)

Soil disturbance by pocket gophers is a major source of natural sediment transport and disturbance. Reference area may have higher emissions than currently estimated

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Step 5: Emission Estimates

• Windblown Dust– Current windblown dust model estimates– Spatially and temporally-resolved

• Specific windblown sources considered:– Agricultural lands– Grasslands– Shrublands– Barren lands

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Agricultural Emissions

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Grasslands

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Shrublands

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Barren Lands

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Step 5: Emission Summary• Shrublands dominant

– Grasslands contribute with a significantly lesser contribution from barren lands

• Agricultural sources in study area appear not to be inventoried

• Based on current inventory evaluation for non-windblown sources in Pima County:– Ag tilling and mining operations ~ 500 tpy PM10 each– Unpaved roads contribute ~4500 tpy; prevalence in study

area unknown but considered low• Animal movement, burrowing emissions unknown

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Step 5: Category 3 Partitioning

• For windblown dust from shrublands, are there areas that are anthropogenically disturbed or impacted?– Reviewing grazing databases– Searching for unpaved road databases

• If anthropogenic influences identified, partition based on:– Level 1: areal extent– Level 2: comparison to reference natural area

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Next Steps

• Study area finalization• Resolve inventory discrepancies• Attempt to assess potential relevance of animal-

related emissions or impacts• Partition scrubland emissions• Assess dust definition feasibility• Finalize draft SAWE Case Study report by end of

year• Begin Salt Creek Wilderness Case Study