Development and Reliability of Standard Land Development

Development and Reliability of Standard Land Development

Models

Robert Pitt1, Celina Bochis2, and Geosyntec Project Team Members

1Cudworth Professor of Urban Water Systems, University of Alabama, Tuscaloosa 2Former Postdoctoral Researcher, University of Alabama, Tuscaloosa

Land Development Surveys • Land development characteristics for different land

uses have been collected for many locations throughout the US as part of stormwater research projects, stormwater management plans, and model calibration efforts.

• This information was collated and statistically evaluated to identify similarities and trends in the major land use features for different locations in the country as part of this EPA Standards Development Process.

• WinSLAMM used this information along with data from the National Stormwater Quality Database (NSQD) to develop regional calibrations and to evaluate different stormwater management alternatives.

Example Field Data Collection for Development Characteristics for Different

Land Uses in an Area • Delineation of the watersheds and neighborhoods • Single land use neighborhood surveys: 6 to 12 per study

area land use to determine the variability of the development characteristics

• Site Inventory has 2 parts: – Field data collection – Aerial photographic measurements of different land

covers • Each site has at least two photographs taken (now

supplemented with Google Street View): – one as a general view – one as a close-up of the street texture and gutter/curb

interface

Presenter

Presentation Notes

The process of field data collections starts in the office with the watershed and neighborhoods delineation For each land use, about 6 to 12 Neighborhoods were investigated Site inventory has 2 parts… When in the filed we look for….

Field Inventory Sheet Prepared for Each Neighborhood When in the field we look for:

1. Roof types (flat or pitched) and material (now supplemented by small drone cameras)

2. Roof connections (connected, disconnected)

3. Pavement conditions and texture (smooth, intermediate, rough)

4. Storm drainage type (grass swales, curb and gutters, and roof drains)

Presenter

Presentation Notes

Look for such things as: Different land covers: roofs, streets, parking areas Pavement condition and texture Roof types and connections Storm drainage characteristics (grass swales, curb and gutters, and the roof drains) If more then one type of the roof connection was identify, we took an inventory of all visible roof drains in the study block by keeping tallies of each type of drain connection The percentage per connection type was put on the sheet. This the map of our study area. L.S.C. Watershed has approximately 8 sq. miles and about 16 major land uses from residential, commercial, institutional to industrial and freeway land uses. The predominant land use in the watershed is residential, and therefore it was subdivided according to its density The soil is represented by sandy loam and silt loam soils, in about equal amounts

Village Creek Site (SWMA 002) Birmingham, AL

Presenter

Presentation Notes

Here is an example of general view and close-up view for a residential site.

Example of 1 m monochromatic aerial photograph (USGS photo)

Presenter

Presentation Notes

Here is an example of aerial photograph that we used previously used

Example of high resolution color satellite image (Google)

Presenter

Presentation Notes

Here is the same area but as the high resolution satellite image

General Land Use Categories (modified based on local definitions and project needs)

• Residential (separated by development age and veg type) – High, medium, low density – Apartments, multi- family units

• Commercial – Strip commercial, shopping centers – Office parks, downtown business district

• Industrial – Manufacturing (power plants, steel mills, cement plants) – Non-manufacturing (warehouses) – Medium and Heavy Industrial (lumber yards, junk and auto salvage

yards, storage areas) • Institutional

– Schools, churches, hospitals, nursing homes • Open Space

– Parks, cemeteries, golf courses – Vacant spaces, undeveloped areas

• Freeway

Presenter

Presentation Notes

A typical urbanized area might have one or more land uses categories The main land uses are: Residential Commercial Industrial Institutional Open space Freeway All with their sub-categories.

High Density Residential Area, with and without extensive vegetation

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Presentation Notes

High Density Residential Area, with and without extensive vegetation and a lot of impervious cover

High Rise Residential Apartments

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Presentation Notes

An example of high rise residential units, heavily impervious

Open Space: Cemetery

Freeway

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Presentation Notes

Example of open space with little impervious cover Example of freeway land use, mostly paved but with opportunities of stormwater management

Light Industrial Area (Warehouses)

Scrap yard and Storage Area

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Presentation Notes

Example of industrial land use with highly impervious with all the source areas connected to storm drains Example of another industrial area with storage areas unpaved, but with compacted soil that acts like an impervious cover

Institutional School

Strip Commercial

Presenter

Presentation Notes

Example of institutional land –with a lot of impervious cover, some landscape or with unpaved area (playground) acting like impervious surfaces Example of commercial land, highly impervious with all the source areas connected

Little Shades Creek Watershed Average Land Cover Distribution High Density Residential (6 houses/acre)

TIA = 25%

DCIA = 15%

TR-55 = 52 - 65%

Presenter

Presentation Notes

This pie chart shows the average land cover distribution for H.D. Residential land use For a typical HD Res land use in this region we can expect that the major land cover to be landscaped subdivided in front and back landscaped (according with the house position on the property) AND 25% of the area is covered with impervious surfaces are broken down into 4 subcategories 15% DCIA TR-55 average of 52% impervious area

TIA = 20%

DCIA = 15%

TR-55 = 25-52%

TIA = 10%

DCIA = 6.7%

TR-55 = 20-25%

TIA = 61%

DCIA = 60%

TR-55 = 85%

TIA = 67%

DCIA = 64%

TR-55 = 85%

Presenter

Presentation Notes

Pie charts show the distribution of land cover (source areas) Box plots show the variability of land cover (source areas) There is a similarity in the land cover distribution for all residential areas. the main land cover is landscape: front landscape for high and medium density residential back landscape for low density The pattern is changed for commercial, industrial or freeways land use, where impervious surfaces are now dominant Commercial LU - where the source that contributes runoff is some how equally divided among parking lots, roof directly connected , streets and front landscape

Little Shades Creek and Jefferson Co. Drainage Areas: DCIA by Land Use

Presenter

Presentation Notes

All freeways were drained by grass swales, so all had 0% DCIA

Great Lakes

East Coast

South East

Central

North West

South West

National Stormwater Quality Database (NSQD) and Geographical Calibration Areas

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LAND USE TOTAL EVENTS PERCENTAGE

Residential 2,979 35 Mixed Residential 1,245 15 Commercial 1,288 15 Mixed Commercial 525 6 Institutional 115 1 Industrial 887 10 Mixed Industrial 269 3 Freeway 763 9 Open Space 404 5 TOTAL 8,602 100

Number of Events and Land Use Coverage in NSQD ver. 3

NSQD Data: These grouped box-whisker plots sort all of the data by land use. Kruskal-Wallis analyses indicate that all constituents have at least one significantly different category from the others. Heavy metal differences are most obvious.

NSQD data: Residential area concentrations grouped by EPA rain zones. Zones 1-4 are east half of country, zones 5-9 are western half of country. Zones 3 and 7 are the wettest zones.

Commer. Indus. Instit. Open Space

Resid. Freeways/Highways

Total by Region

Central 4 2 4 1 5 3 19 East Coast 3 1 1 1 2 3 11 Great Lakes (the USGS/DNR files)

6 4 4 2 11 4 31

Northwest 2 1 1 1 3 3 11 Southeast 7 2 3 5 8 4 29 Southwest 5 1 1 1 2 3 13 Total by Land Use

27 11 14 11 31 20 114

Number of Standard Land Use Files Used for Each Category

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Many study areas throughout the US had detailed land development information and concurrent stormwater quality data and were organized by geographical area and land use:

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Rainfall Distribution Modeling for Different Locations and Land Uses

Can be used to establish treatment goals for a targeted annual runoff objective: - About 90% of the annual runoff

corresponds to a rain depth from about 1.5 to 3.5 inches

- About 70% of the annual runoff corresponds to a rain depth from about 0.75 to 2 inches

Source Area Modeling Identifies Major Sources of Flows and Pollutants for Critical Events: - As expected, directly connected impervious areas are the major runoff sources for up to about 2 inch rains in residential areas, but then landscaped areas are more important. They are always important in most commercial and industrial areas.

Presenter

Presentation Notes

Using these data and SLAMM model we are able to predict the sources of runoff and sources of pollutants Also we can see from what development characteristics affect the stormwater quality for different rains For low density residential, for very small rains, the directly connected area (pitched roofs and streets) contribute runoff. In this case streets are dominant As the rain depth increases, the contribution of streets decreases and is replaced by landscape which contributes to runoff

ArcGIS and WinSLAMM • Typically user might use GIS to develop source

areas and then manually enter values into the WinSLAMM interface

• Developing databases and tools to automate that process

• ArcSLAMM tool will produce WinSLAMM compliant databases per drainage or catchment area which can then be run in batch mode through WinSLAMM

Conclusions • Standard land use information and associated

development characteristics affect stormwater quality and quantity.

• Surface coverage of different elements in each land use do not vary as much throughout the country as does random variations in directly connected imperviousness.

• Obtaining regional standard land use information is a good investment, but it requires field work and evaluation of aerial imaging.

Conclusions (cont.)

• Historical tools used to automate the collection of this information was found to result in significant errors.

• Newer high resolution tools (such as 6 inch LiDAR, light detection and ranging) has been shown to be quite effective in the collection of most of this data, but field surveys are still needed for supplemental information.

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Development and Reliability of Standard Land Development