water quality survey in the isahaya bay using uav
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Water Quality Survey in the
Isahaya Bay Using UAV
Haruhiro Hidaka, Susumu Ogawa
Nagasaki University
11
背景:諫早湾における汚染過程
Red Tide
Construction of the levee
Background
Blue-Green Algae2 2
Present Problems
1. The number of samples is limited.
2. It is difficult to measure a wide water area.
3. Research depends on the weather.
4. Water quality changes every moment.
3Actual water quality survey 3
Objectives
1. Estimate water quality at high resolution that can not be measured with satellites.
2. Improve limit for the number of sample.
3. Capture changes of water quality in time
series.Phantom4
4 4
Study Area
Tokyo
Levee
Isahaya
Bay
Polluted
Water
5 5
6 6
Methods
PhotoScan
Image
Synthesis
Multivariable
Analysis
Image
Capture
UAV(Phantom4)
Image
Correction PhotoShop
Polluted Water
Water Quality
Measurements
Water
Sampling
Water Quality
Map
Accuracy
Check
500 pictures 7 7
Result on Multivariate analysis
Water Quality Indices DeterministicCoefficient
Evaluation
Chlorophyll-a R² =0.974 Very good
Conductivity R² =0.736 Good
Turbidity R² =0.997 Very Good
pH R² =0.809 Good
Salt Content R² =0.863 Good8 8
Chlorophyll-a in Spring
(May 7, 2016)LOW HIGH
9
Chlorophyll-a in Summer
(Aug 5, 2016)LOW HIGH
10
Discussion
・Only RGB has limit for water quality mapping. Thus, multivariable analysis should be added byinfrared imagery.
・Four multivariable analysis will be needed for every seasons.
11
Conclusions
1. Continuous distribution map of water quality was obtained by UAV
2. The temporal and spatial resolution of water quality can be greatly improved with UAV.
3. Turbidity and chlorophyll-a had high correlations with RGB bands. Other water quality will be improved by adding infraredbands.
12
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