Statistical estimation of Rosetta branch water quality using multi-spectral data

Peer review under the responsibility of National Water Research Center.

Figures & data

Fig. 1 Imagery covering the area under study of Rosetta branch with sampling locations.

Table 1 Descriptive statistics of water quality variables along Rosetta branch.

Water quality parameter	Near west bank				Near east bank				Law 48/1982
	Min	Max	Mean	Std dev.	Min	Max	Mean	Std dev.
pH	7.06	8.04	7.42	0.18	7.24	8.27	7.62	0.28	7–8.5
DO (mg/l)	0.2	6.9	1.17	1.36	0.3	8.2	3.8	2.6	>5
TA (mg/l)	124	287	203	36	111	229	170	30	150
TDS (mg/l)	182	776	427	150	178	473.54	317	97	500
TSS (mg/l)	8	98	30.2	18.0	8	34	20.08	6.40
OP (mg/l)	0.023	5.9	0.517	0.724	0.02	0.696	0.199	0.119
BOD (mg/l)	2	90	26.9	20.6	1	35	9.4	8.0	6
COD (mg/l)	3	108	34.5	24.9	2	39	13.1	9.0	10
Chl-a (mg/l)	0.5	148.96	12.56	21.81	0.5	59.28	11.44	12.59

Table 2 Paired-samples t test of water quality variables between both sampling sets.

Paired	Paired differences					t	df	Sig. (2-tailed)
	Mean	Std. deviation	Std. error mean	95% confidence interval of the difference
				Lower	Upper
W (pH) – E (pH)	−0.2859	0.3191	0.0774	−0.4499	−0.1218	−3.694	16	0.002
W (DO) – E (DO)	−3.9294	3.1160	0.7558	−5.5315	−2.3273	−5.199	16	0.000
W (TDS) – E (TDS)	166.353	155.840	37.797	86.227	246.479	4.401	16	0.000
W (TSS) – E (TSS)	10.118	21.371	5.183	−0.870	21.106	1.952	16	0.069
W (TA) – E (TA)	34.118	37.311	9.049	14.934	53.301	3.770	16	0.002
W (OP) – E (OP)	0.521824	0.463154	0.112331	0.283692	0.759955	4.645	16	0.000
W (BOD) – E (BOD)	25.765	23.860	5.787	13.497	38.033	4.452	16	0.000
W (COD) – E (COD)	35.941	31.222	7.572	19.888	51.994	4.746	16	0.000
W (Chl-a) – E (Chl-a)	−0.57286	1.53392	0.40996	−1.4585	0.31280	−1.397	13	0.186

Table 3 The regression equations of water quality parameters over Rosetta branch (east side).

W.Q. parameters (log scale)	R^2	Equations
pH	0.607	=0.713 − (4.336/B7) + (9.166/B6) + (42.187/B3) − (9.630/B5) + (16.042/B4)
DO	0.440	=−3.706 − (124.179/B7) + (213.452/B6) + (1033.090/B3)
TDS	0.818	=3.413 − (172.209/B2) + (10.851/B8) − (60.614/B4)
TSS	0.388	=3.003 + (94.349/B5) − (460.265/B3) − (208.127/B1) + (20.013/B7) − (49.474/B6)
TA	0.769	=2.517 − (101.969/B2) + (8.111/B7) − (31.720/B6) + (83.209/B1)
OP	0.189	=−0.516 + (81.002/B7) − (131.951/B5)
Chl-a	0.656	=5.906 + (727.830/B5) − (321.436/B6) − (1596.481/B3) − (1136.814/B4) + (647.486/B1)
BOD	0.476	=4.106 − (600.763/B2) + (88.565/B7) − (231.461/B6)
COD	0.429	=3.684 − (494.576/B2) + (66.693/B7) − (176.324/B6)
Total Coliform	0.484	=25.255 − (586.640/B5) + (363.640/B7) − (2942.243/B1) − (1853.699/B2)
Fecal Coliform	0.137	=9.001 − (1041.002/B3)

Fig. 2 Normality of residuals for chlorophyll-a.

Fig. 3 Normality of residuals for TSS.

Fig. 4 Normality of residuals for pH.

Fig. 5 Relationship between observed and calculated values of chlorophyll-a (east side).

Fig. 6 Relationship between observed and calculated values of TDS (east side).

Fig. 7 Relationship between observed and calculated values of pH (east side).

Table 4 The regression equations of water quality parameters over Rosetta branch (west side).

W.Q. parameters (log scale)	R^2	Equations
pH	0.705	=0.834 + (3.078/B6) − (8.214/B5) + (14.249/B4) + (4.625/B2)
DO	0.376	=0.555 + (307.840/B6) − (122.283/B5) − (484.740/B1)
TDS	0.628	=3.355 − (178.064/B2)
TSS	0.448	=2.808 − (126.321/B6) − (510.892/B3) + (204.425/B5) − (39.815/B7)
Total alkalinity	0.273	=2.550 − (57.887/B2)
Ortho-phosphate	0.800	=0.239 − (139.542/B4)
COD	0.159	=2.262 − (199.123/B2)
BOD	0.119	=2.118 − (195.854/B2)
Chlorophyll	0.499	=2.532 + (640.043/B5) − (110.210/B7) − (1225.524/B3) − (253.469/B6)
Total Coliform	0.358	=−2.855 + (2597.908/B1) + (3935.777/B3) − (1323.041/B4) − (2004.980/B2)
Fecal Coliform	0.594	=−4.763 + (7658.036/B1) + (4977.938/B3) − (5443.499/B4) − (4416.997/B2) + (677.579/B5) − (685.448/B8) + (1114.290/B6) + (518.395/B7)

Fig. 8 Relationship between observed and calculated values of chlorophyll-a (west side).

Fig. 9 Relationship between observed and calculated values of TDS (west side).

Fig. 10 Relationship between observed and calculated values of pH (west side).