GIS III Exercise 04 – Model spread of a chemical plume v.1b, April 2010

Desired Learning Outcomes Become familiar with EPA / NOAA’s ALOHA (Areal Locations Of Hazardous Atmospheres)

plume modeling software Model the spread of a hazardous chlorine gas plume Intersect the outline of the contaminant plume with other layers to assist with evacuation

and/or assess damage to people and/or property Introduction In Exercise 03, you were introduced to how GIS can be used to calculate route times and use that information to predict the fastest route to a given destination (e.g., the route displayed on a satellite navigation system). In this exercise, you will be introduced to how GIS can be used with other software to produce models of chemical plumes. This is a very useful application of GIS in emergency and disaster response, and it will provide insight as to how non-GIS software packages can provide output that can be incorporated into ArcGIS. CAUTION – You will want to employ DOS 8.3 naming conventions (limit names to 8 characters, using only alphanumeric characters and underscores) in this exercise! Step 1 – Download and install ALOHA and ArcMap Tools on your computer If you are using the NJCU GIS Lab, Aloha software will be installed. If you are working from home, please follow directions from the USEPA website to download ALOHA. Also, you will need to download and install ALOHA ArcMap tools, which you can do by following directions from the NOAA website. A short description of ALOHA features can be found here. An extensive ALOHA user manual can be found here. Be sure your Security is set so that you have Full Control to the ALOHA folder that will be installed in Program Files. Step 2 – Download Jersey City Airphotos and Copy JC Streets to your Exr04 folder Full-color, high-resolution orthophotos (ortho-rectified airphotos) are now available through New Jersey’s NJGIN website, which serves as a clearinghouse for many types of GIS data. Directions for downloading airphotos can be found here. Download / unzip the nine (9) Jersey City airphoto tiles (JPEG2000 format) shown in the Selection Panel below to your Exr04 folder:

After you have downloaded the airphotos to your Exr04 folder, use FTP to scroll to ftp://geosrv.njcu.edu/GISStudent/GIS_III_Exercise_Data/GIS_III_Exr04_input_data and copy all the jc_lnstreets files into your exr04 folder.

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Step 3 – Open ArcMap, set Layer Properties to Decimal Degrees coordinates Discussion - We have a dilemma: the airphotos and street lines are in State Plane (projected) coordinates, but ALOHA only works with geographic coordinates (Degrees-Minutes-Seconds or Decimal Degrees). ArcMap can work around this by projecting “on the fly” to Decimal Degrees if the layer projections are correctly defined. Read on….this might be a problem. Procedure – Open ArcMap. From the Table of Contents (ToC), select Layers > Properties > Coordinate

System tab. Select Predefined > Geog Coord Systems > North America > North American Datum 1983; press Apply

Select the General tab in this window (see below); confirm that both the Map and Display

units are set to Decimal Degrees (see below); press OK:

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Step 4 – Add jc_lnstreets and check projection of the layer From ArcMap, select File > Add Data, scroll to your folder, select jc_lnstreets; press Add:

You may IMMEDIATELY see a potential problem if you get a “Warning” screen about an undefined coordinate system. Select OK to load the shapefile into ArcMap anyway. When the ArcMap window appears, place the cursor on the line feature in the View, and

note the measurement units in the lower RH corner:

Place cursor here

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Discussion - State Plane Feet numbers “mixing” with Decimal Degrees measurement units, creating an incorrect projection. Decimal Degrees can only range from + to – 90 in the Y (N-S) direction and from + to – 180 in the X (E-W) direction, much smaller numbers than the 600,000 to 700,000 displayed in ArcMap at present. It is reasonable to infer that jc_lnstreets is in a State Plane Feet coordinate system, because these numbers would be correct for Jersey City in SP NAD 1983 coordinates. However, because the layer’s projection is not “defined” as State Plane, ArcMap has no basis from which to re-project this layer to Decimal Degrees coordinates. If we use Define Projection in ArcToolbox, we should be able to work around the problem.

Procedure – In ArcToolbox, select Data Management Tools > Projections and Transformations >

Define Projection (see below):

When the Define Projection window appears (below), select jc_lnstreets as input dataset.

Note that the Coordinate System is currently unknown:

Select the Browse button (see above), scroll to through Projected Coordinate Systems to

NAD 1983 (Feet) and select New Jersey (below); press Add, then Apply, OK

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Press OK when the Define Projection window appears (below), jc_lnstreets now defined:

When the status window (below) indicates the process is completed, press Close:

The ArcMap view re-appears (below) at the same place spatially (coordinates read 600,000 to 700,000) when you started the Define Projection operation, but no jc_lnstreets are visible!

Don’t Panic! This may be a good thing. Rt-click on jc_lnstreets in the ToC > Zoom to Layer, then place the cursor on the layer. Note that the coordinates of the view (below) in the lower RH corner now reflect the CORRECT numbers for the Decimal Degrees coordinate system:

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fly”. Select File > Add Data, scroll to your Exr04 folder, and select all 9 airphotos with the *.jp2

extension; select Add:

Step 5 – Add airphotos to the ArcMap view and check projection Since the airphotos you downloaded are from the State of New Jersey, it is reasonable to expect that they are already correctly defined as SP NAD 1983 Feet, and will project “on the

When the Map View returns, you can tell immediately that the airphoto projections have been properly defined because they have re-projected “on the fly” and fit well with jc_lnstreeets:

File > Save your project

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Step 6 – Open ALOHA, set parameters, create plume “threat zone” Discussion - Now that we have some basic ArcMap layers in place for our modeling exercise, we can turn our attention back to ALOHA. Jointly developed by the USEPA and NOAA, ALOHA is a state-of-the-art modeling program designed to be used for real chemical and fire emergencies as well as training exercises. Be sure your Security is set so that you have Full Control to the ALOHA folder that will be installed in Program Files. There are many factors that affect the severity of atmospheric chemical releases and/or terrorist attacks and the damage that they may cause, but near the top of the list are things like: Nature, toxicity, and concentration of the chemical Wind speed and direction Distribution and number of people near, and downwind of, the release This exercise will give you some experience with, and insight into, how professionals can use programs like ALOHA and ArcGIS to manage disasters and minimize damage and loss of life. To maximize your learning, you may want to connect to the ALOHA User Manual here as we work though our hypothetical chlorine gas release. NOTE: It is OK to leave ALOHA open during the entire exercise; it will not interfere with ArcMap operations. We will use the parameters set forth in the ALOHA “Guided Tour” (start p.33), but rather than use their hypothetical example of a chlorine gas release in Sioux Falls, SD, we will select a

e intersection of JF Kennedy Blvd and Bergen leaking tanker truck involved in an accident at thAv in Jersey City. This locae tion is less than ½ mile southwest of the NJCU campus, with coordinates of -74.09028 degrees West and 40.70359 degrees North.

Location of leaking chlorine gas tanker

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Procedure - Open ALOHA (Start > Programs > ALOHA). At the Disclaimer screen (below); click OK

A Text Summary screen appears that shows the steps and data needed to run the model:

SITE Data, CHEMICAL Date, and Atmospheric Data. Select Site Data > Location (below)

Select Jersey city from the Site Location screen (below); press Select:

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From the same spot in the ALOHA menu bar, select Site Data > Building Type; we will leave the parameters alone; press OK:

Next, from the ALOHA Menu bar, choose Setup > Chemical > Chlorine; press Select

Various parameters for Chlorine are automatically entered into the Text Summary box:

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Next, Atmospheric data is needed. From the menu bar, select Setup > Atmospheric > User Input. In the Atmospheric Options window that opens, make the following selections:

o Wind speed = 10 mph o Wind from SSW o Msrmt height = 3 meters o Ground roughness = Urban or Forest o Could cover = between clear and partly cloudy o Press OK

In the Atmospheric Options 2 box, enter the following:

o 72 deg F o Stability class D (relatively stable) o No Inversion o Humidity = medium o Press OK

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The next step is to describe the release. From the menu bar, select Setup > Source > Tank; select the following values:

o Horizontal cylinder o Enter diameter = 7.5 feet o Enter length = 20 feet o The computer returns a volume of 6,610 gallons o Press OK

Leave the settings on the next screen as they appear below:

o Tank contains liquid Chemical stored at ambient temperature o

o Press OK

The next window (Liquid Mass or Volume) asks for the amount of liquid chemical present.

Assume that the tanker truck is 80% full; other values are automatically filled in; press OK:

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The next screen is “Area and Type of Leak” (below); assume that the tank has been cracked, so the opening should be modeled as rectangular:

o Length = 10 inches o Width = 0.10 inches o Leak through a hole o Press OK

The next screen is “Height of the Tank Opening”; assume that the crack is near the top of

the tanker; select “90% of the way to the top of the tank”; press OK:

AL to model the timing, duration, and amount of release.

OHA now has enough information

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The Text Summary screen displays the results of the computer simulation. Note the summary highlighted in red at the bottom of the screen:

From the Menu Bar, select Display > Source Strength; a graph showing the rate of release

vs duration of release, arbitrarily limited to 1 hour by ALOHA, is shown:

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The next step with ALOHA is create a “threat zone plot”, which is a map of the extent of the toxic gas plume. Later, you will be able to export this plot out of ALOHA and into ArcMap, where you can overlay it on your existing layers and perform analysis. From the ALOHA menu bar, select Display > Threat Zone:

A panel showing three different Acute Exposure Guideline Levels (AEGLs) appears. If you click

elp (above), a panel explaining Toxic Levels of Concern (LOC) appears (below); click AEGL: H

The panel explains the three AEGL levels used by ALOHA:

AEG Level 3, the most serious, is the concentration (in ppm of the chemical in an airborne state) above which death is imminent. Level 2 is the concentration above which serious, long-lasting

ALOHA can create the 3 AEGLs for each of 5 different time periods of exposure: o 10 minutes o 30 minutes o 60 minutes (the default) o 4 hours o 8 hours This should enable the GIS user to map / model how the plume will spread over time. Return to the original “Toxic Level of Concern” panel (click the “Back” button to move back

one screen) and click OK:

effects can occur. Level 1 is the concentration above which non-disabling discomfort can occur.

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” represents the region in which there is 95% confidence that the plume will remain, given the CURRENT input parameters. The Threat Zone plot appears (below). The “confidence line

From the ALOHA menu bar, select File > Save As, scroll to Program Files > ALOHA, and

save the ALOHA file as 60_min.alo (see below) press Save:

Scroll to Program Files > ALOHA (below, left); you should see 60_min.alo as well as

ALO_FTP.PAS. RENAME ALO_FTP.PAS to 60_min.pas (below, right)

Rename!

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From the Standard Toolbar, click on the ALOHA “hula girl” icon (see below):

Step 7 – Save ALOHA threat zone .PAS file as Geodatabase & Import into ArcMap If necessary, open the ArcMap .mxd you saved at the end of Step 5.

n alohaExtproj instructional screen appears (below). Although this window tells you to set to

OK

AArcMap to D-M-S, Decimal Degrees are also supported. The screen instructs the user howdetermine the coordinates of the release site, which you already did in Step 6. Press .

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se site: When the coordinate input screen appears (below), enter the coordinates of the releaX-coord = -74.09028 and Y-coord = 40.70359; press OK:

Scroll to Program Files > ALOHA (below); select the appropriate .PAS file; press Open:

A “Save Aloha Geodatabase as” screen appears, prompting you to save as “CHLORINE”:

Modify that name slightly, to CL_60min (see below); press Save:

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w). The threat zone is imported into ArcMap, at the proper location, with a text box of info (belo

Change the scale in the Scale window to 1:10000 to increase the size of the map (drag the

text box to a more convenient spot on the map):

NJCU is in the path of this release, including a lethal dose of 20 ppm extending onto campus!

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Create a layout with: o Title o North Arrow o Scale Bar in Miles o Legend

Export the layout as a JPG to your Exr04 folder and embed it in your writeup:

Step 8 – Create layout and write up this exercise

In your writeup, describe some of the ways that you could see this information being used in

real time, such as intersecting the plume with the streets layer in order to evacuate homes and the NJCU campus, or making the data available online to guide emergency responders.

DUE – Approximately 2 weeks from date of assignment – consult your syllabus for details.