Drones: Application of novel technologies to increase ... · Drones offer significant potential to collect water samples & hydrochemical data May prove significantly safer, cheaper,

Drones: Application of novel technologies to increase efficiency of

water sampling methodologies

Heather Lally, Ian O’Connor, Liam Broderick, Mark Broderick, Olaf Jensen, Conor Graham

IntroductionLarge scale hydrological monitoring programmes of large open lakes(e.g. WFD Lake Monitoring programme) require for followingconsiderations:

Introduction

Drones offer significant potential to collect water samples &hydrochemical data

May prove significantly safer, cheaper, and time and resourceefficient

Significant limitations were highlighted:

• Volume of water collected is low (60-330 ml)

• Successful and consistent water capture rates are low (60-83%)

• Significant differences in hydrochemical parameters obtained via drone samples versus boat samples

• No cost benefit analyses conducted

Research Aims

Assess the applicability of drones for openlake sampling

Evaluate whether water samples andphysico-chemical data collected using

drones satisfies the WFD objectives

Examine whether drones can offer a

quicker, cost effective, less labour

intensive and safer lake sampling protocol

DJI Matrice 600 Pro

Methods & Materials

Zodiac inflatable boat

Water sampling payload

Experimental Field Trials

• Paired water samples (3 boat and 3 drone) at each sampling site

• 4 in-situ real-time water chemistry parameters: pH, dissolved oxygen, conductivity, temperature

• >10 water chemistry parameters: chlorophyll a, nitrate, nitrite, total oxidised nitrogen, ammonia, ortho-phosphate, alkalinity, colour, total phosphorus, heavy metals

• Sample capture success rates recorded

No. of sampling

sites

Surface area (ha)

Included in the EPA WFD

Lake MP

WFD Alkalinity Status*

WFD Typology

Class*

WFD Status**

Lough Fee 1 174 - - -Lough Inagh 1 310 - - -

Lough Conn 2 4,704 ✓ High 12 ModerateLough Derg 3 13,000 ✓ High 12 Moderate

Lough Mask 3 8,218 ✓ High 12 GoodBallyquirkelake

2 73.6 ✓ Moderate 6 Bad

Results – Experimental Field Trials

1. Volume of water sampled

Previous Research:• 60 ml (Ore et al. 2013; 2015, Detweiler et al. 2015; Chung et al. 2015, Song

et al. 2017)

• 130 ml (Koparan & Koc 2016; Koparan et al., 2018a,b)

• 250-330 ml (Terada et al. 2018)

• 390 ml (Koparan et al. 2020)

This study: 2 L


2. Sampling success rates

Previous Research:• 90% (Ore et al. 2013) for indoor trials but 69-83% outdoor trials

(Ore et al. 2013; 2015)

• 60-66% (Koparan & Koc 2016; Koparan et al., 2018)

• 96% (Koparan et al. 2020)

This study: 100 %


3. Comparison of variables

Previous Research: Majority didn’t compare results• Temperature change of ~1°C (Ore et al. 2013,2015; Detweiler et al.

2015)

• Temperature change of ~0.5°C (Chung et al. 2015)

• Temperature different? (Koparan & Koc 2016)

• Temperature similar (Song et al. 2017)

• Koporan et al. (2018) incorporated statistical tests• Temperature (t=0.12,d.f.=18,p=0.91); Conductivity (t=1.59,

d.f.=18,p=0.13)• Oxygen (t=10.1, df=18, p<0.001, mean diff.= 0.25mg/L) (7.18

mg/L vs. 6.93mg/L)• pH (t=3.3,d.f.18, p=0.004, mean diff.= 0.04)• Chloride (t=-12.1,d.f,=18, p<0.001, mean diff.=1.49mg/L)

(5.46mg/L vs.3.97mg/L)

Boat

Drone


10

30

50

70

90

110

130

150

170

10 30 50 70 90 110 130 150 170

Only used sites if results were

above LOD for all 6 replica samples

This study

Boat


Paired t = -0.416, d.f. = 9, p = 0.69

Mean diff. = -1.27

Lough Derg Site 1

Lough Derg Site 2

Lough Derg Site 3

Lough Mask Site 1

Lough Mask Site 2

Lough Mask Site 3

Ballyquirke Site 1

Ballyquirke Site 2

Lough Inagh

Lough Fee

Lough Conn Site 1

Lough Conn Site 2

This study

Drone

Boat

Drone


Paired t = -1.99, d.f. = 7, p = 0.09

Mean diff. = -0.25

Lough Derg Site 1

Lough Derg Site 2

Lough Derg Site 3

Lough Mask Site 1

Lough Mask Site 2

Lough Mask Site 3

Ballyquirke Site 1

Ballyquirke Site 2

Lough Inagh

Lough Fee

Lough Conn Site 1

Lough Conn Site 2

This study

Boat

Drone


Paired t = 1.19, d.f.= 4, p = 0.3

Mean diff. = 0.0005

Lough Derg Site 1

Lough Derg Site 2

Lough Derg Site 3

Lough Mask Site 1

Lough Mask Site 2

Lough Mask Site 3

Ballyquirke Site 1

Ballyquirke Site 2

Lough Inagh

Lough Fee

Lough Conn Site 1

Lough Conn Site 2

This study

Boat

Drone


Paired t = -2.46, d.f.= 11, p = 0.031

Mean diff.=-0.048

Lough Derg Site 1

Lough Derg Site 2

Lough Derg Site 3

Lough Mask Site 1

Lough Mask Site 2

Lough Mask Site 3

Ballyquirke Site 1

Ballyquirke Site 2

Lough Inagh

Lough Fee

Lough Conn Site 1

Lough Conn Site 2

This study


Variable Test statistic

No. of pairs p value Mean difference

True colour* -0.872 12 0.41 -0.78

Hardness* 0.85 6 0.43 1.67

Silica* 0.89 12 0.39 0.06

TON* 0.775 4 0.5 0.002

Chloride# -0.614 10 0.54 0.04

Temperature# -0.94 12 0.35 -0.017

Conductivity* 1.89 12 0.09 12.2

Dissolved oxygen#

-0.63 12 0.53 0.056

*Paired t-test #Wilcoxon signed rank testTON = Total oxidised nitrogen

This study


4. Comparison of variability

Assessment of precision between boat & drone• Calculated the coefficient of variation for each variable, for each

method, at each site (n=3)

• Firstly, tested overall CoV of all variables between both methods:

Z = -0.197, p = 0.85 (Averages: boat 3.29%; drone 3.76%)

• Secondly, compared CoV for each variable and compared each statistically • Gives assessment of precision between boat & drone

Assessment of precision between boat & drone

*Square root transformed, #Wilcoxon signed rank test, TON= Total oxidised nitrogen, TP = Total phosphorous

Variable Test statistic

No. of pairs

p value Average CV%

Boat Drone

True colour* -1.54 12 0.15 2.9 4.3

Hardness 2.87 6 0.043 7.3 3.9

Silica* -0.89 12 0.4 7.6 8.7

TON* -0.19 4 0.86 1.3 1.6

Chloride -0.15 10 0.89 0.9 0.9

Alkalinity# -0.77 10 0.44 6.6 9.4

Chlorophyll-a -1.25 8 0.25 6.4 8.9

TP# -0.41 5 0.69 6.9 5.9

pH# -1.81 12 0.07 1.1 0.6

Temperature# -1.73 12 0.08 0.6 0.4

Conductivity* 0.08 12 0.94 0.6 0.6

Dissolved oxygen 0.2 12 0.84 0.5 0.5

Results - Cost Benefit Analyses

How much time does it take to get a sample?

Estimated time for a

boat sample

Estimated time for a drone

sample

Key differences

Sampling time(3 reps)

0:49:21 0:22:38 Inflatable boat set up & dismantling

No. of persons 2 2

Total person minutes 1:38:42 0:45:16

Biosecurity measures 0:26:49 0:11:03 More equipment needing disinfecting with boat sampling

No. of persons 2 2

Total person minutes 0:53:38 0:22:06

Total estimated person minutes per sampling site

2:32:20 1:07:22

Results - Cost Benefit Analyses

Drone sampling X 2.3 times

faster

Drone sampling X 3 times faster

Drone sampling X 3.4 times

faster

Boat sampling X 2.6 times

cheaper

In Conclusion• Water samples & physio-chemical data collected by

drones satisfy Ireland’s WFD objectives for lake watermonitoring

• Drone is approximately 3 times faster than boat

• Boat is approximately half the capital outlay

compared to the drone system

• Drone is far safer than boat, for both personnel and

reduces the biosecurity risk

Overall, use of drone reduces the cost of sampling, is

safer and reduces the risk of invasive species being

introduced

Acknowledgements This research (2017–W–MS-28) is funded by the Environmental

Protection Agency (EPA) Ireland as part of their EPA Research Programme

2014-2020

EPA Steering Committee (Dr Ruth Little, Ray Smith, Gerard Hannon, Dr

Iq Mead & Cecilia Hegarty)

Alan Stephens & team EPA Castlebar

Research Assistants: Ashley Johnson & Nicole Perich

Maura O’Connor & Colin Folan – Lough Inagh

Bowen Ormsby - Lough Feeagh

Thank you!!Twitter: @DroPLEtS18, @heatherLally;

@MFRCGMIT; @modelhelisrvcs; @ioconn; @TheConorGraham

Facebook: Marine and Freshwater Research Centre; Model Heli Services

Website: dronesforlakesampling.com

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Drones: Application of novel technologies to increase ... · Drones offer significant potential to collect water samples & hydrochemical data May prove significantly safer, cheaper,