Understanding DWAs in First Nations Systems A Data Mining Approach

Transcription

1 Understanding DWAs in First Nations Systems A Data Mining Approach Emma Thompson E. McBean, Y. Post

2 65 percent of First Nations experienced a Drinking Water Advisory (DWA) between

3 The federal government has committed to end long-term boil water advisories on reserves within five years by investing $1.8 billion

4 Overview Objectives Methods Data Mining Overview of Data Methodology Models Occurrence of DWAs Duration of DWAs Frequency of DWAs Conclusions Next steps

5 Objectives To analyze historical data using data mining techniques to provide insight and inform decision makers Aim is to identify key attributes associated with the occurrence, duration and frequency of DWAs using decision tree analysis

6 Methods

7 Data Compilation Data for 800 drinking water systems from AANDC Roll-Up reports Data for 1,500 individual DWA events from Health Canada and provincial records System Info Source Type Population Certification Remoteness etc. Province Band Name System Name Community DWA Events Start Date End Date Reason

8 Data Mining An anlytical tool used to learn new information from a large database Find correlations or patterns This research used Decision Tree Analysis in RapidMiner Studio Basic

9 Decision Trees Generated by repeatedly splitting the data according to input attributes (recursive partitioning) Creates a classification model that predicts the value of the target attribute based on input attributes Target Attributes: Occurrence Frequency Duration Will a DWA occur? Will a DWA re-occur? How long will a DWA last?

10 Number of Systems Frequency Data Frequency of DWAs in 1 system ranged from 0 44 times Half of all systems have DWA 1 time Frequency (# times)

11 Number of DWA Events Duration Data Duration ranges from 1 3,277 days (9 years) Half of all events last <14 days Duration of DWA (days)

12 Input attributes Attribute Province Water Source Type System Age Treatment Class Operator Certification Environmental Class Geographic/Remoteness Zone Distribution Pipe Length Number of Homes Trucked Description Location Surface water (SW), groundwater (GW), GUDI Based on construction date Based on complexity (Level I, II, III, Small system) Operator class meets treatment class requirement Based on latitude Distance and access to nearest service centre Total length in metres Number of homes with water delivered

13 Validation Decision trees were validated using random subsets of the data to test prediction accuracy. Model parameters were optimized to obtain trees with highest prediction accuracy, in this case 60-70%. Frequency Tree: Accuracy = 70.08% +/- 5.55% True (No) True (Yes) Prediction (No) Prediction (Yes)

14 Models

15 Occurrence Will a DWA occur in a given facility? YES NO AB # Homes Trucked? 82 > 82 # Homes Piped? 10 > 10 Province? Atlantic BC MB ON QC SK Source? Pipe Length? Pipe Length? GW Population? GUDI # Homes SW Piped? MTA Unknown 400m > 400m Population? Unknown > 6,544m 6,544m 205 > > > 72 Yukon

16 Frequency Will a DWA occur more than once? >1 time 1 time AB Atlantic Max Daily Volume? 254m 3 /d > 254m 3 /d System 23 Age? > 23 BC Max Daily Volume? Unknown 175m 3 /d > 175m 3 /d # Homes Piped? 61 > 61 Province? MB Source? SW GW # Homes Trucked? 54 > 54 ON QC SK Yukon Max Daily Volume? Population? Unknown 71m 3 /d > 71m 3 /d 322 > 322 Max Daily Volume? 579m 3 /d > 579m 3 /d

17 Number of Systems Occurrence & Frequency Trends in occurrence and frequency vary by province Distribution properties including pipe length, maximum daily volume and population served are key attributes DWA = No Yes BC AB SK MB ON QC Atl. YK Province

18 Number of Systems Occurrence & Frequency Source Type is also important Surface water and GUDI systems and are more likely to have re-occurring DWAs than groundwater systems time > 1 time GW GUDI SW Source Type

19 Duration Will a DWA last longer than 2 weeks? >2 wks 2 wks Not Required Province? Alberta Atlantic BC 1 st Operator Treatment Certified? No No Operator Not req. Level Treatment Class? # Homes Piped? None Level I Level II Level III Small System 233 > 233 Pipe Length? Population? # Homes Trucked? 4199m > 4199m 495 > > 3 Yes Pipe Length/ Connection? 30m > 30m Pipe Length? 2 nd Op. Treatment Certified? 430m > 430m Not req. No 2 nd Op. No Not req. level Yes

20 Number of DWA Events Duration Operator certification influences duration of DWAs DWAs in systems without a trained operator are more likely to last longer than 2 weeks weeks > 2 weeks No Operator Not Required Not Certified Not Required Level Fully Certified Primary Operator Treatment Certification

21 Conclusions Province and operator certification are key attributes associated with the occurrence, duration and frequency of DWAs Drinking water problems are typically resolved more quickly when operators are trained. Decision trees are a powerful tool that can be used to investigate historical trends and predict likely outcomes.

22 Next Steps Further investigation is required to understand provincial differences, as First Nations are federally regulated. Data gaps and inconsistencies exist in system information at the time of each DWA event. An up-to-date nation-wide database would provide more accurate results

23 Questions?

24 References Government of Canada Budget Health Canada Information request by CBC. Neegan Burnside National Assessment of First Nations Water and Wastewater Systems - National Roll-Up Report. RapidMiner GmbH Studio Basic Ed