Ambient Water Quality: Update April 19, 2017 Point Statics for - - PowerPoint PPT Presentation

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Ambient Water Quality: Update April 19, 2017 Point Statics for - - PowerPoint PPT Presentation

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TDS/Nitrogen Management Plan for the Santa Ana River Basin Groundwater Monitoring Requirements Ambient Water Quality: Update April 19, 2017 Point Statics for 20-Year Moving Average 1. Annualized Averages 2. At least 3 years of water quality (TDS

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SLIDE 1

TDS/Nitrogen Management Plan for the Santa Ana River Basin Groundwater Monitoring Requirements

Ambient Water Quality: Update

April 19, 2017

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SLIDE 2

Point Statics for 20-Year Moving Average

2

  • 1. Annualized Averages
  • 2. At least 3 years of water quality (TDS or NO3-N) in 20

year period

  • 3. Shapiro Wilk test for normality
  • 4. Point Statistics – mean plus t*standard error of the

mean

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SLIDE 3

Method Shapiro-Wilk Test for Normality

3

  • Annualized Averages
  • Shapiro-Wilk test for

normality to remove “Most Discordant Value” (MDV) iteratively until data is normalized

  • Assumes “normal” data
  • Bias towards low values
  • No apparent limit on the

number of iterations

  • Rejects data that may

correspond to event changes

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SLIDE 4

4

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SLIDE 5

5

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SLIDE 6
  • 2.0
  • 1.5
  • 1.0
  • 0.5

0.0 0.5 1.0 1.5 2.0 5 10 15 20 25

Normal Quantile NO3-N

1003134

  • 2.0
  • 1.5
  • 1.0
  • 0.5

0.0 0.5 1.0 1.5 2.0 5 10 15 20 25

Normal Quantile NO3-N

1003134

Potential Bias on Bimodal data

6

Mean = 6.8 Mean = 8.5 Remove 1 MDV

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SLIDE 7
  • 2.0
  • 1.5
  • 1.0
  • 0.5

0.0 0.5 1.0 1.5 2.0 2.5 5 10 15 20 25

Normal Quantile NO3-N

1003134

  • 2.0
  • 1.5
  • 1.0
  • 0.5

0.0 0.5 1.0 1.5 2.0 5 10 15 20 25

Normal Quantile NO3-N

1003134

Potential Bias on Bimodal data

7

Mean = 5.6 Mean = 8.5 Remove 2 MDV

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SLIDE 8
  • 2.0
  • 1.5
  • 1.0
  • 0.5

0.0 0.5 1.0 1.5 2.0 2 4 6 8 10 12 14 16

Normal Quantile NO3-N

1003134

  • 2.0
  • 1.5
  • 1.0
  • 0.5

0.0 0.5 1.0 1.5 2.0 5 10 15 20 25

Normal Quantile NO3-N

1003134

Potential Bias on Bimodal data

8

Mean = 4.2 Mean = 8.5 Remove 3 MDV

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SLIDE 9
  • 2.0
  • 1.5
  • 1.0
  • 0.5

0.0 0.5 1.0 1.5 2.0 2.5 2 4 6 8 10 12

Normal Quantile NO3-N

1003134

  • 2.0
  • 1.5
  • 1.0
  • 0.5

0.0 0.5 1.0 1.5 2.0 5 10 15 20 25

Normal Quantile NO3-N

1003134

Potential Bias on Bimodal data

9

Mean = 3.1 Mean = 8.5 Remove 4 MDV

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SLIDE 10
  • 2.0
  • 1.5
  • 1.0
  • 0.5

0.0 0.5 1.0 1.5 2.0 0.5 1 1.5 2 2.5 3 3.5

Normal Quantile NO3-N

1003134

  • 2.0
  • 1.5
  • 1.0
  • 0.5

0.0 0.5 1.0 1.5 2.0 5 10 15 20 25

Normal Quantile NO3-N

1003134

Potential Bias on Bimodal data

10

Mean = 2.1 Mean = 8.5 Remove 5 MDV

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SLIDE 11
  • 2.0
  • 1.5
  • 1.0
  • 0.5

0.0 0.5 1.0 1.5 2.0 5 10 15 20 25

Normal Quantile NO3-N

1003134

  • 2.0
  • 1.5
  • 1.0
  • 0.5

0.0 0.5 1.0 1.5 2.0 5 10 15 20 25

Normal Quantile NO3-N

1003134

Updated Shapiro Wilk

11

Calculated Statistic = 6.8 Mean = 4.8 No MDV Removed

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SLIDE 12

12

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SLIDE 13

Questions?

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SLIDE 14

Criteria for Determining Point Statistics: Identifying Outliers:

1. Limit S-W iterations to no more than 2 times 2. Median absolute difference: Nitrate-N > 5x; TDS > 10x

Checking for Normality:

1. Linear Normality: Pass = Point Statistic 2. Log Transform Normality: Pass = Point Statistic 3. Fail Both = ‘Average’

14

Outcome:

  • 1. Fewer data points

removed

  • 2. Accounts for bimodal

and non-linear trends

  • 3. Does not significantly

change contouring

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SLIDE 15

1996 – 2015 AWQ Data

Fail

Flow Diagram

Pass Shapiro- Wilks Test

MDV 5x (NO3-N) /10x (TDS)

Remove MDV Mean +SE UCL84 Fail

S-W Log Transform

No Pass GM + GSE UCL84 Mean Median

n < 3 or Detects = 0

Yes No Yes No Yes

Remove MTV <2 & Max C >1

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SLIDE 16

16

5000 10000 15000 20000 25000 30000 35000 40000 Period 1 2000 2003 2006 2009 2012 [CELLRANGE] [CELLRANGE] [CELLRANGE] [CELLRANGE] [CELLRANGE] [CELLRANGE]

Annualized Nitrate Samples and Outliers Removed

Nitrate Nitrate Outliers 5000 10000 15000 20000 25000 30000 35000 40000 Period 1 2000 2003 2006 2009 2012 [CELLRANGE] [CELLRANGE] [CELLRANGE] [CELLRANGE] [CELLRANGE] [CELLRANGE]

Annualized TDS Samples and Outliers Removed

TDS TDS Outliers