Table 1 Statistics on the occurrence of water blooms in the Hanjiang River
Year
|
1992
|
1998
|
2000
|
2003
|
2006
|
2008
|
2016
|
Date
|
Feb.17~
Mar.7
|
Feb.16~
Mar.5
|
Feb.28~ Mar.18
|
Mar.11~
Mar.30
|
Sep.16~
Sep.27
|
Feb.15~ Mar.8
|
Feb.24~ Mar.10
|
Duration(days)
|
18
|
20
|
20
|
19
|
11
|
22
|
15
|
Location
|
Qianjiang River section
|
Shayang section
|
Zhongxiang section
|
Zhongxiang to Jijiazui section
|
Zhongxiang to Shayang section
|
Wuhan section
|
Shayang section
|
Dominant species
|
Diatom
|
Diatom;Chlorophyta
|
Diatom
|
Diatom;Chlorophyta
|
Chlorophyta
|
Diatom
|
Diatom
|
Algal density(107/L)
|
1.57
|
2.2
|
4.0
|
0.57
|
0.73
|
1.6
|
3.13
|
Table 2 Correlation between band reflectivity and measured chla concentration
Band
|
B1
|
B2
|
B3
|
B4
|
B5
|
B6
|
B7
|
Pearson Correlation Coefficient
|
-0.044
|
-0.55*
|
-0.119
|
-0.075
|
-0.645*
|
-0.515*
|
-0.365
|
Significance(two-tailed)
|
0.877
|
0.033
|
0.673
|
0.791
|
0.009
|
0.049
|
0.181
|
Table 3
Correlation between the band reflectance ratio and the measured chla concentration
Serial number
|
Band combination
|
Correlation coefficient
|
Serial number
|
Band combination
|
Correlation coefficient
|
Serial number
|
Band combination
|
Correlation coefficient
|
1
|
B7/B6
|
0.564
|
26
|
B7-B2
|
0.496
|
51
|
B5/(B4+B3)
|
-0.302
|
2
|
B7/B5
|
0.679
|
27
|
B7-B1
|
-0.115
|
52
|
B5/(B3+B2)
|
-0.311
|
3
|
B7/B4
|
-0.180
|
28
|
B6-B5
|
0.513
|
53
|
B5/(B2+B1)
|
-0.574
|
4
|
B7/B3
|
-0.165
|
29
|
B6-B4
|
-0.239
|
54
|
B4/(B3+B2)
|
0.646**
|
5
|
B7/B2
|
0.489
|
30
|
B6-B3
|
-0.150
|
55
|
B4/(B2+B1)
|
0.390
|
6
|
B7/B1
|
-0.208
|
31
|
B6-B2
|
0.383
|
56
|
B3/(B2+B1)
|
0.108
|
7
|
B6/B5
|
0.59
|
32
|
B6-B1
|
-0.300
|
57
|
B7/(B6+B5+B4)
|
0.269
|
8
|
B6/B4
|
-0.227
|
33
|
B5-B4
|
-0.621
|
58
|
B7/(B5+B4+B3)
|
0.044
|
9
|
B6/B3
|
-0.183
|
34
|
B5-B3
|
-0.505
|
59
|
B7/(B4+B3+B2)
|
-0.005
|
10
|
B6/B2
|
0.359
|
35
|
B5-B2
|
-0.289
|
60
|
B7/(B3+B2+B1)
|
-0.015
|
11
|
B6/B1
|
-0.265
|
36
|
B5-B1
|
-0.688
|
61
|
B6/(B5+B4+B3)
|
-0.058
|
12
|
B5/B4
|
-0.384
|
37
|
B4-B3
|
0.309
|
62
|
B6/(B4+B3+B2)
|
-0.096
|
13
|
B5/B3
|
-0.234
|
38
|
B4-B2
|
.653**
|
63
|
B6/(B3+B2+B1)
|
-0.110
|
14
|
B5/B2
|
-0.426
|
39
|
B4-B3
|
-0.319
|
64
|
B5/(B4+B3+B2)
|
-0.367
|
15
|
B5/B1
|
-0.463
|
40
|
B3-B2
|
0.498
|
65
|
B5/(B3+B2+B1)
|
-0.402
|
16
|
B4/B3
|
-0.070
|
41
|
B2-B1
|
-.730**
|
66
|
B4/(B3+B2+B1)
|
0.535*
|
17
|
B4/B2
|
0.484
|
42
|
B7/(B6+B5)
|
.674**
|
67
|
LNB1
|
0.024
|
18
|
B4/B1
|
-0.138
|
43
|
B7/(B5+B4)
|
0.173
|
68
|
LNB2
|
-.599*
|
19
|
B3/B2
|
0.211
|
44
|
B7/(B4+B3)
|
-0.164
|
69
|
LNB3
|
0.003
|
20
|
B3/B1
|
-0.108
|
45
|
B7/(B3+B2)
|
0.132
|
70
|
LNB4
|
0.003
|
21
|
B2/B1
|
-0.480
|
46
|
B7/(B2+B1)
|
0.061
|
71
|
LNB5
|
-0.712**
|
22
|
B7-B6
|
0.610*
|
47
|
B6/(B5+B4)
|
0.031
|
72
|
LNB6
|
-0.559*
|
23
|
B7-B5
|
0.609*
|
48
|
B6/(B4+B3)
|
-0.197
|
73
|
LNB7
|
-0.401
|
24
|
B7-B4
|
-0.069
|
49
|
B6/(B3+B2)
|
0.022
|
|
|
|
25
|
B7-B3
|
-0.004
|
50
|
B6/(B2+B1)
|
-0.075
|
|
|
|
Table 4
Results of model expression
Model category
|
Equation expression
|
R2
|
Significance
|
Linear function
|
y=-43.519+140.642x
|
0.455
|
0.006
|
Logarithmic function
|
y=56.080+47.655lnx
|
0.402
|
0.011
|
Inverse function
|
y=51.217-15.683/x
|
0.347
|
0.021
|
Quadratic function
|
y=182.687-1107.274x+1705.076x2
|
0.626
|
0.001
|
Cubic function
|
y=107.908-486.149x+1540.013x3
|
0.677
|
0.001
|
Compound model
|
y=0.067 x 200485.870x
|
0.339
|
0.023
|
Power function
|
y=372.418x4.121
|
0.297
|
0.036
|
S-Curve model
|
y=EXP(5.478-1/x)
|
0.197
|
0.055
|
Growth model
|
y=EXP(-2.710+12.208x)
|
0.339
|
0.023
|
Exponential function
|
y=0.067EXP(12.208x)
|
0.339
|
0.023
|
Logisticmodel
|
y=1/(1/u +15.086 x 4.988x)
|
0.339
|
0.023
|
Table 5
Decision Coefficient (R2) and Root Mean Square Error (RMSE) under Different Numbers of Hidden Layer Nodes
Hidden layer nodes
|
R2
|
RMSE
|
1
|
0.74436
|
4.0361
|
2
|
0.72602
|
4.1853
|
3
|
0.81383
|
4.2065
|
4
|
0.98918
|
3.1462
|
5
|
0.88942
|
3.3619
|
6
|
0.87764
|
3.6473
|
7
|
0.87938
|
3.6497
|
8
|
0.84758
|
3.8654
|
9
|
0.71904
|
4.1782
|
Table 6 Statistical analysis of the inter-annual variation of the chlorophyll a concentration value in each monitoring section
|
Huangzhuang Station
|
Shayang Station
|
Yuekou Station
|
Xiantao Station
|
Zongguan Station
|
Average
(μg/L)
|
|
Min
(μg/L)
|
Month
|
Max
(μg/L)
|
Month
|
Min
(μg/L)
|
Month
|
Max
(μg/L)
|
Month
|
Min
(μg/L)
|
Month
|
Max
(μg/L)
|
Month
|
Min
(μg/L)
|
Month
|
Max
(μg/L)
|
Month
|
Min
(μg/L)
|
Month
|
Max
(μg/L)
|
Month
|
2000
|
3.282
|
4
|
39.869
|
3
|
2.941
|
10
|
32.893
|
3
|
10.517
|
9
|
34.601
|
3
|
8.567
|
9
|
19.425
|
2
|
5.057
|
10
|
28.303
|
3
|
14.614
|
2001
|
2.774
|
10
|
32.508
|
3
|
2.783
|
2
|
13.517
|
9
|
3.896
|
2
|
20.161
|
4
|
3.139
|
4
|
12.709
|
2
|
2.781
|
4
|
25.854
|
2
|
8.769
|
2002
|
2.778
|
10
|
23.794
|
3
|
3.027
|
10
|
22.244
|
9
|
7.953
|
9
|
24.065
|
10
|
3.119
|
10
|
14.741
|
3
|
2.776
|
10
|
22.566
|
1
|
12.032
|
2003
|
3.113
|
9
|
35.643
|
10
|
2.839
|
10
|
17.061
|
9
|
8.702
|
1
|
26.894
|
10
|
4.161
|
9
|
18.753
|
2
|
11.919
|
9
|
25.036
|
4
|
12.739
|
2004
|
2.815
|
4
|
27.861
|
3
|
3.138
|
3
|
33.531
|
4
|
2.826
|
2
|
17.023
|
9
|
4.133
|
9
|
22.323
|
2
|
2.916
|
3
|
23.058
|
4
|
13.858
|
2005
|
2.912
|
2
|
26.994
|
4
|
2.826
|
9
|
13.864
|
10
|
3.115
|
2
|
11.095
|
10
|
4.971
|
10
|
32.796
|
2
|
11.377
|
9
|
26.536
|
3
|
11.945
|
2006
|
2.885
|
2
|
19.623
|
4
|
2.779
|
3
|
33.282
|
2
|
6.177
|
3
|
33.408
|
2
|
5.654
|
10
|
35.843
|
2
|
3.609
|
9
|
30.43
|
2
|
14.227
|
2007
|
2.816
|
4
|
16.27
|
3
|
3.654
|
4
|
17.021
|
10
|
2.777
|
10
|
22.217
|
3
|
6.275
|
10
|
30.673
|
2
|
6.638
|
2
|
25.212
|
4
|
12.226
|
2008
|
3.149
|
10
|
26.519
|
3
|
4.249
|
4
|
41.837
|
2
|
2.791
|
10
|
24.79
|
9
|
4.991
|
10
|
33.049
|
2
|
3.472
|
9
|
32.433
|
2
|
14.771
|
2009
|
2.803
|
9
|
9.883
|
2
|
2.781
|
9
|
4.495
|
2
|
3.544
|
10
|
23.717
|
9
|
4.565
|
4
|
13.587
|
2
|
4.629
|
4
|
22.566
|
2
|
8.322
|
2010
|
10.092
|
3
|
28.259
|
10
|
3.242
|
2
|
33.15
|
9
|
2.781
|
10
|
21.399
|
9
|
4.433
|
4
|
18.473
|
2
|
4.591
|
9
|
20.51
|
2
|
12.365
|
2011
|
2.95
|
10
|
13.635
|
4
|
3.016
|
10
|
9.468
|
3
|
2.779
|
2
|
17.173
|
9
|
3.136
|
9
|
20.588
|
2
|
2.779
|
3
|
29.878
|
2
|
10.42
|
Table 7 Statistics of average Water Level and Discharge statistics from February to March in Xiantao Hydrological Station
2000
|
2001
|
2002
|
2003
|
2004
|
2005
|
2006
|
2007
|
2008
|
2009
|
2010
|
2011
|
Water Level(m)
|
23.233
|
25.63
|
24.209
|
23.954
|
25.529
|
24.995
|
24.257
|
23.979
|
23.954
|
24.657
|
24.716
|
24.681
|
Discharge(m³/s)
|
353.424
|
1181.695
|
501.169
|
471.847
|
1191.017
|
840.271
|
695.424
|
534.458
|
597.542
|
784.763
|
808.797
|
890.915
|
Table 8 Statistics of average Flow velocity statistics from February to March in Zongguan Hydrological Station
|
2000
|
2001
|
2002
|
2003
|
2004
|
2005
|
2006
|
2007
|
2008
|
2009
|
2010
|
2011
|
flow velocity(m/s)
|
0.168
|
0.358
|
0.274
|
0.166
|
0.341
|
0.278
|
0.267
|
0.170
|
0.230
|
0.314
|
0.298
|
0.279
|