Emily M. Zechman Department of Civil Engineering North Carolina State University

Agent-Based Modeling to Simulate Contamination Events and to Analyze

Threat Management Strategies in Water Distribution Systems

Emily M. ZechmanDepartment of Civil EngineeringNorth Carolina State University

Contamination Event Management Strategy

• Management strategy specifies actions and reactions of decision maker– Broadcast no-drink alerts– Flush system– Isolate portion of system– Treat contaminant in-situ

Evaluate a Management Strategy

• Maintain public health

• Maintain fire fighting flows

• Maintain flow to critical care facilities

• Avoid inciting panic due to false alarms

Interaction of Actors during a Contamination Event

Water Distribution

System

Utility Manager

Consumers

Perpetrator

Media

Utilities Operations Staff

Public Health Services

Agent Based Modeling Framework

• Simulate interactions of actors among one another and with water distribution system

• Predict effectiveness of alternative management strategies

Agent Based Model

• A computer program that simulates an actor– Receives information from other agents and the

environment– Has capabilities (set of rules) to decide on an action

Agent Based Model

Environmental Information Action

Agent Based Modeling Frameworkfor WDS Contamination Event

Decision Maker Agent

Demand

Public Broadcast

Unusual Water Quality

at Sensors

Change Hydraulics

Water Distribution

System Model

Exposure

Word-of-mouth

Consumer Agents

156

110 111

45

190117 16

43

97

34 3815

35

58

5

237

22119

36

43

34

138 2

1232

4821

89

675914

9837

54 57 7 11

76 20 34

19

5314

13

4

58

2045

33

1

1

Each Consumer Agent represents 10 households

2510 Residential Consumer Agents

Contaminant Source

Industrial Demand

Residential Demands (# Consumer Agents per node)

37

Illustrative Case Study

Decision Maker Agent

Set of Scenarios

Consumer Agents modeled only

Conservative Decision Maker Agent

Adaptive Decision Maker Agent

Scenario DrinkWord-of-

mouthBroadcast Reaction

All-Broadcast

Open hydrants

Targeted Broadcast

Add Sensors

Number Sick

Consumer Agents

Number Consumer Agents Not

Drinking

1 872 807

Decision Maker AgentConsumer Agent

-Drink water once every 4 hrs.

-Ifconsumer agent drinks waterandcontaminant concentration at node > 0 mg/L

then agent is sickened and stops drinking within 2 - 6 hours

Contaminant Source Introduced

12:00am

SensorSensor with unusual WQ

Percentage of Sick Consumer Agents

0 – 20% 20 – 40%40 – 60%60 – 80% > 80%

9837

54 57 7

11

76 20 34

19

13

2045

33

1

53

58

1232

48

21

89

5967

13

82

34

43

37

12:20am



0 – 20% 20 – 40%40 – 60%60 – 80% > 80%

9837

54 57 7

11

76 20 34

19

13

2045

33

1

53

58

1232

48

21

89

5967

13

82

34

43

37

12:40am



0 – 20% 20 – 40%40 – 60%60 – 80% > 80%

9837

54 57 7

11

76 20 34

19

13

2045

33

1

53

58

1232

48

21

89

5967

13

82

34

43

37

1:00am



0 – 20% 20 – 40%40 – 60%60 – 80% > 80%

9837

54 57 7

11

76 20 34

19

13

2045

33

1

53

58

1232

48

21

89

5967

13

82

34

43

37

1:20am



0 – 20% 20 – 40%40 – 60%60 – 80% > 80%

9837

54 57 7

11

76 20 34

19

13

2045

33

1

53

58

1232

48

21

89

5967

13

82

34

43

37

1:40am



0 – 20% 20 – 40%40 – 60%60 – 80% > 80%

9837

54 57 7

11

76 20 34

19

13

2045

33

1

53

58

1232

48

21

89

5967

13

82

34

43

37

2:00am



0 – 20% 20 – 40%40 – 60%60 – 80% > 80%

9837

54 57 7

11

76 20 34

19

13

2045

33

1

53

58

1232

48

21

89

5967

13

82

34

43

37

2:20am



0 – 20% 20 – 40%40 – 60%60 – 80% > 80%

9837

54 57 7

11

76 20 34

19

13

2045

33

1

53

58

1232

48

21

89

5967

13

82

34

43

37

2:40am



0 – 20% 20 – 40%40 – 60%60 – 80% > 80%

9837

54 57 7

11

76 20 34

19

13

2045

33

1

53

58

1232

48

21

89

5967

13

82

34

43

37

3:00am



0 – 20% 20 – 40%40 – 60%60 – 80% > 80%

9837

54 57 7

11

76 20 34

19

13

2045

33

1

53

58

1232

48

21

89

5967

13

82

34

43

37

3:20am



0 – 20% 20 – 40%40 – 60%60 – 80% > 80%

9837

54 57 7

11

76 20 34

19

13

2045

33

1

53

58

1232

48

21

89

5967

13

82

34

43

37

3:40am



0 – 20% 20 – 40%40 – 60%60 – 80% > 80%

9837

54 57 7

11

76 20 34

19

13

2045

33

1

53

58

1232

48

21

89

5967

13

82

34

43

37

4:00am



0 – 20% 20 – 40%40 – 60%60 – 80% > 80%

9837

54 57 7

11

76 20 34

19

13

2045

33

1

53

58

1232

48

21

89

5967

13

82

34

43

37

4:20am



0 – 20% 20 – 40%40 – 60%60 – 80% > 80%

9837

54 57 7

11

76 20 34

19

13

2045

33

1

53

58

1232

48

21

89

5967

13

82

34

43

37

4:40am



0 – 20% 20 – 40%40 – 60%60 – 80% > 80%

9837

54 57 7

11

76 20 34

19

13

2045

33

1

53

58

1232

48

21

89

5967

13

82

34

43

37

5:00am



0 – 20% 20 – 40%40 – 60%60 – 80% > 80%

9837

54 57 7

11

76 20 34

19

13

2045

33

1

53

58

1232

48

21

89

5967

13

82

34

43

37

5:20am



0 – 20% 20 – 40%40 – 60%60 – 80% > 80%

9837

54 57 7

11

76 20 34

19

13

2045

33

1

53

58

1232

48

21

89

5967

13

82

34

43

37

5:40am



0 – 20% 20 – 40%40 – 60%60 – 80% > 80%

9837

54 57 7

11

76 20 34

19

13

2045

33

1

53

58

1232

48

21

89

5967

13

82

34

43

37

6:00am



0 – 20% 20 – 40%40 – 60%60 – 80% > 80%

9837

54 57 7

11

76 20 34

19

13

2045

33

1

53

58

1232

48

21

89

5967

13

82

34

43

37

6:20am



0 – 20% 20 – 40%40 – 60%60 – 80% > 80%

9837

54 57 7

11

76 20 34

19

13

2045

33

1

53

58

1232

48

21

89

5967

13

82

34

43

37

6:40am



0 – 20% 20 – 40%40 – 60%60 – 80% > 80%

9837

54 57 7

11

76 20 34

19

13

2045

33

1

53

58

1232

48

21

89

5967

13

82

34

43

37

7:00am



0 – 20% 20 – 40%40 – 60%60 – 80% > 80%

9837

54 57 7

11

76 20 34

19

13

2045

33

1

53

58

1232

48

21

89

5967

13

82

34

43

37

7:20am



0 – 20% 20 – 40%40 – 60%60 – 80% > 80%

9837

54 57 7

11

76 20 34

19

13

2045

33

1

53

58

1232

48

21

89

5967

13

82

34

43

37

7:40am



0 – 20% 20 – 40%40 – 60%60 – 80% > 80%

9837

54 57 7

11

76 20 34

19

13

2045

33

1

53

58

1232

48

21

89

5967

13

82

34

43

37

8:00am

9837

54 57 7

11

76 20 34

19

13

2045

33

1

53

58

1232

48

21

89

5967

13

82

34

43

37



0 – 20% 20 – 40%40 – 60%60 – 80% > 80%



0 – 20% 20 – 40%40 – 60%60 – 80% > 80%

9837

54 57 7

11

76 20 34

19

13

2045

33

1

53

58

1232

48

21

89

5967

13

82

34

43

37

9:00am



0 – 20% 20 – 40%40 – 60%60 – 80% > 80%

859 sick consumer agents

794 consumer agents not drinking

9837

54 57 7

11

76 20 34

19

13

2045

33

1

53

58

1232

48

21

89

5967

13

82

34

43

37

10:00am



All-Broadcast

Open hydrants

Targeted Broadcast

Add Sensors

Number Sick

Consumer Agents


Drinking

1 872 807

2 706 1246


-If consumer agent stops drinking water, then notify another consumer agent within 10 min - 1 hr

- If agent receives word-of-mouth information, then stop drinking immediately

* Average for 5 random trials

* *



All-Broadcast

Open hydrants

Targeted Broadcast

Add Sensors

Number Sick

Consumer Agents


Drinking

1 872 807

2 706 1246

3 373 2510


-If consumer agent receives all-broadcast, then stop drinking within 30 min – 6 hrs.

-If sensors show unusual water quality, then send no-drink broadcast to all consumer agents after 2 hrs.



All-Broadcast

Open hydrants

Targeted Broadcast

Add Sensors

Number Sick

Consumer Agents


Drinking

1 872 807

2 706 1246

3 373 2510

4 520 1056


-If sensors show unusual water quality, then open hydrant at sensor node after 2 hrs.



All-Broadcast

Open hydrants

Targeted Broadcast

Add Sensors

Number Sick

Consumer Agents


Drinking

1 872 807

2 706 1246

3 373 2510

4 520 1056

5 339 2510




All-Broadcast

Open hydrants

Targeted Broadcast

Add Sensors

Number Sick

Consumer Agents


Drinking

1 872 807

2 706 1246

3 373 2510

4 520 1056

5 339 2510

6 444 1428


-If sensors show unusual water quality, then send targeted broadcast after 2 hrs. Reduce reaction time to 1 hr.

-If consumer agent receives all-broadcast, then stop drinking within 30 min – 6 hrs.

-If consumer agent receives targeted broadcast, then stop drinking within 10 min – 1 hr.



All-Broadcast

Open hydrants

Targeted Broadcast

Add Sensors

Number Sick

Consumer Agents


Drinking

1 872 807

2 706 1246

3 373 2510

4 520 1056

5 339 2510

6 444 1428

7 375 1437


-If sensors show unusual water quality, then add another sensor in the near vicinity after 2 hrs. Reduce reaction time to 1 hr.



All-Broadcast

Open hydrants

Targeted Broadcast

Add Sensors

Number Sick

Consumer Agents


Drinking

1 872 807

2 706 1246

3 373 2510

4 520 1056

5 339 2510

6 444 1428

7 375 1437

8 400 900


-If a sensor shows unusual water quality, then open a hydrant at the sensor node after 2 hrs. Reduce reaction time to 1 hr.



All-Broadcast

Open hydrants

Targeted Broadcast

Add Sensors

Number Sick

Consumer Agents


Drinking

1 872 807

2 706 1246

3 373 2510

4 520 1056

5 339 2510

6 444 1428

7 375 1437

8 400 900

9 286 1292


12:00am

SensorSensor with unusual WQHydrant opened

Contaminant Source Introduced


0 – 20% 20 – 40%40 – 60%60 – 80% > 80%

9837

54 57 7

11

76 20 34

19

13

2045

33

1

53

58

1232

48

21

89

5967

13

82

34

43

37

12:20am



0 – 20% 20 – 40%40 – 60%60 – 80% > 80%

9837

54 57 7

11

76 20 34

19

13

2045

33

1

53

58

1232

48

21

89

5967

13

82

34

43

37

12:40am



0 – 20% 20 – 40%40 – 60%60 – 80% > 80%

9837

54 57 7

11

76 20 34

19

13

2045

33

1

53

58

1232

48

21

89

5967

13

82

34

43

37

1:00am



0 – 20% 20 – 40%40 – 60%60 – 80% > 80%

9837

54 57 7

11

76 20 34

19

13

2045

33

1

53

58

1232

48

21

89

5967

13

82

34

43

37

1:20am



0 – 20% 20 – 40%40 – 60%60 – 80% > 80%

9837

54 57 7

11

76 20 34

19

13

2045

33

1

53

58

1232

48

21

89

5967

13

82

34

43

37

1:40am



0 – 20% 20 – 40%40 – 60%60 – 80% > 80%

9837

54 57 7

11

76 20 34

19

13

2045

33

1

53

58

1232

48

21

89

5967

13

82

34

43

37

2:00am



0 – 20% 20 – 40%40 – 60%60 – 80% > 80%

9837

54 57 7

11

76 20 34

19

13

2045

33

1

53

58

1232

48

21

89

5967

13

82

34

43

37

2:20am



0 – 20% 20 – 40%40 – 60%60 – 80% > 80%

9837

54 57 7

11

76 20 34

19

13

2045

33

1

53

58

1232

48

21

89

5967

13

82

34

43

37

2:40am



0 – 20% 20 – 40%40 – 60%60 – 80% > 80%

9837

54 57 7

11

76 20 34

19

13

2045

33

1

53

58

1232

48

21

89

5967

13

82

34

43

37

3:00am



0 – 20% 20 – 40%40 – 60%60 – 80% > 80%

9837

54 57 7

11

76 20 34

19

13

2045

33

1

53

58

1232

48

21

89

5967

13

82

34

43

37

3:20am



0 – 20% 20 – 40%40 – 60%60 – 80% > 80%

9837

54 57 7

11

76 20 34

19

13

2045

33

1

53

58

1232

48

21

89

5967

13

82

34

43

37

3:40am



0 – 20% 20 – 40%40 – 60%60 – 80% > 80%

9837

54 57 7

11

76 20 34

19

13

2045

33

1

53

58

1232

48

21

89

5967

13

82

34

43

37

4:00am



0 – 20% 20 – 40%40 – 60%60 – 80% > 80%

9837

54 57 7

11

76 20 34

19

13

2045

33

1

53

58

1232

48

89

5967

13

82

34

43

37

21

4:20am



0 – 20% 20 – 40%40 – 60%60 – 80% > 80%

9837

54 57 7

11

76 20 34

19

13

2045

33

1

53

58

1232

48

89

5967

13

82

34

43

37

21

4:40am



0 – 20% 20 – 40%40 – 60%60 – 80% > 80%

9837

54 57 7

11

76 20 34

19

13

2045

33

1

53

58

1232

48

89

5967

13

82

34

43

37

21

5:00am



0 – 20% 20 – 40%40 – 60%60 – 80% > 80%

9837

54 57 7

11

76 20 34

19

13

2045

33

1

53

58

1232

48

89

5967

13

82

34

43

37

21



0 – 20% 20 – 40%40 – 60%60 – 80% > 80%

5:20am

9837

54 57 7

11

76 20 34

19

13

2045

33

1

53

58

1232

48

89

5967

13

82

34

43

37

21



0 – 20% 20 – 40%40 – 60%60 – 80% > 80%

5:40am

9837

54 57 7

11

76 20 34

19

13

2045

33

1

53

58

1232

48

89

5967

13

82

34

43

37

21

6:00am



0 – 20% 20 – 40%40 – 60%60 – 80% > 80%

9837

54 57 7

11

76 20 34

19

13

2045

33

1

53

58

1232

48

89

5967

13

82

34

43

37

21



0 – 20% 20 – 40%40 – 60%60 – 80% > 80%

7:00am

9837

54 57 7

11

76 20 34

19

13

2045

33

1

53

58

1232

48

89

5967

13

82

34

43

37

21



0 – 20% 20 – 40%40 – 60%60 – 80% > 80%

8:00am

9837

54 57 7

11

76 20 34

19

13

2045

33

1

53

58

1232

48

21

89

5967

13

82

34

43

37

303 Sick Consumer Agents

1175 Consumer Agents Not Drinking



All-Broadcast

Open hydrants

Targeted Broadcast

Add Sensors

Number Sick

Consumer Agents


Drinking

1 872 807

2 706 1246

3 373 2510

4 520 1056

5 339 2510

6 444 1428

7 375 1437

8 400 900

9 286 1292


0

500

1000

1500

2000

2500

3000

1 2 3 4 5 6 7 8 9

Scenario

Num

ber

Con

sum

er A

gent

s

Sickened Consumer Agents Consumer Agents Not Drinking

Results for 9 Scenarios

5 6 7 8 9 3 4 1 2

Error bars show range of results for 5 random trials.

Observations and Future Work

• Agent-based modeling framework provides capabilities to model interaction of actors in a water contamination event

• Additional modeling capabilities should be investigated

• Agent-based modeling framework will enable optimization of management strategies

Acknowledgements

• This work is supported by National Science Foundation (NSF) under Grant No. CMS-0540316 under the DDDAS program.

Management Strategies for a Contamination Event

• Strategies based on – Amount of information available– Level and credibility of t threat– Options for containment

• Open fire hydrant flush system• Open/close valves to isolate and flush contaminant• Broadcast to consumers to stop drinking• Inject chemical for in situ treatment

2:50am


Number of Sick Consumer Agents

0 - 5 5 - 1010 - 2020 - 30 > 30

Evaluating Management Strategies

• Metrics– Measure number of sickened people– Maintain flows for fire fighting and at critical

care facilities

• Water Distribution Model to simulate contaminant plume and actions dictated by management strategy

Documents

Emily M. Zechman Department of Civil Engineering North Carolina State University