Evaluation of Radarsat-2 quad-pol SAR time-series images for monitoring groundwater irrigation

Figures & data

Figure 1. Study area and ground observation locations.

Table 1. Characteristics and dates of acquired Radarsat-2 satellite images.

Radarsat-2 satellite images characteristics
Ground resolution	10.9 m
Azimuth resolution	4.7 m
Polarization	Quad pol (HH, HV, VH, and VV)
Mode	Fine quad (descending)
Incidence angle	24.6 (near) – 26.4 (far)
Data acquisition dates	08-06-2013
	02-07-2013
	26-07-2013
	19-08-2013
	12-09-2013
	06-10-2013
	30-10-2013
	23-11-2013
	17-12-2013

Figure 2. Daily rainfall of the Berambadi watershed for Radarsat-2 pass duration.

Figure 3. Image processing workflow.

Table 2. The table presents confusion matrix, user's accuracy, producer's accuracy, overall classification accuracy (OA), and the kappa coefficient for all SVM classified outputs from various polarization indices. Where a and b represent respectively irrigated double-croplands (irrigated in Kharif and Rabi cropping seasons) and other (partial groundwater irrigation during or rainfed) croplands.

EqNo	Polarization Indices		Confusion Matrix (%)			User's Accuracy (%)	Producer's accuracy (%)	Overall Accuracy (%)	Kappa (%)
			a	b	Total
1	$\sum _{i=1}^9{\sigma }^{\circ }\mathrm{h}\mathrm{h}\left(i\right)$	a	0	0	0	a = 0, b = 0.63	a = 0, b = 1	62.6	0
		b	37.4	62.6	100
		Total	37.4	62.6	62.6
2	$\sum _{i=1}^9{\sigma }^{\circ }\mathrm{h}\mathrm{v}\left(i\right)$	a	27.2	0.6	27.8	a = 0.98, b = 0.86	a = 0.73, b = 0.99	89.2	75.8
		b	10.2	62.0	72.2
		Total	37.4	62.6	89.2
3	$\sum _{i=1}^9{\sigma }^{\circ }\mathrm{v}\mathrm{v}\left(i\right)$	a	0	0	0	a = 0, b = 0.63	a = 0, b = 1	62.6	0
		b	37.3	62.6	100
		Total	37.4	62.6	62.6
4	$\sum _{i=1}^9{\sigma }^{\circ }\mathrm{v}\mathrm{h}\left(i\right)$	a	27.9	0.6	28.5	a = 0.98, b = 0.87	a = 0.75, b = 0.99	89.9	77.3
		b	9.4	62.1	71.0
		Total	37.4	62.6	90.0
5	$\sum _{i=1}^9{\displaystyle \frac{{\sigma }^{\circ }\mathrm{v}\mathrm{h}\left(\mathrm{i}\right)}{{\sigma }^{\circ }\mathrm{v}\mathrm{v}\left(\mathrm{i}\right)}}$	a	27.2	5.7	32.9	a = 0.83, b = 0.85	a = 0.73, b = 0.91	84.11	65.2
		b	10.1	57.0	67.1
			37.4	62.6	84.2
6	$\sum _{i=1}^9{\displaystyle \frac{{\sigma }^{\circ }\mathrm{h}\mathrm{v}\left(\mathrm{i}\right)}{{\sigma }^{\circ }\mathrm{h}\mathrm{h}\left(\mathrm{i}\right)}}$	a	28.3	7.3	35.6	a = 0.79, b = 0.86	a = 0.76, b = 0.88	83.5	64.5
		b	9	55.4	64.4
			37.4	62.6	83.7
7	$\sum _{i=1}^9{\displaystyle \frac{{\sigma }^{\circ }\mathrm{h}\mathrm{h}\left(\mathrm{i}\right)}{{\sigma }^{\circ }\mathrm{h}\mathrm{v}\left(\mathrm{i}\right)}}$	a	28.8	7	35.8	a = 0.81, b = 0.87	a = 0.77, b = 0.89	84.4	66.4
		b	8.5	55.7	64.2
			37.4	62.6	84.5
8	$\sum _{i=1}^9{\displaystyle \frac{|{\sigma }^{\circ }\mathrm{v}\mathrm{v}\left(\mathrm{i}\right){|}^2}{|{\sigma }^{\circ }\mathrm{h}\mathrm{h}\left(\mathrm{i}\right){|}^2}}$	a	0	0	0	a = 0, b = 0.63	a = 0, b = 1	62.6	0
		b	37.3	62.6	100
			37.4	62.6	62.6
9	$\sum _{i=1}^9{\sigma }^{\circ }\mathrm{v}\mathrm{h}\left(i\right)-{\sigma }^{\circ }\mathrm{v}\mathrm{v}\left(i\right)$	a	35.3	0.7	36	a = 0.98, b = 0.97	a = 0.94, b = 0.99	97.2	93.9
		b	2	62.0	64
			37.4	62.6	97.3
10	$\sum _{i=1}^9{\sigma }^{\circ }\mathrm{v}\mathrm{v}\left(i\right)-{\sigma }^{\circ }\mathrm{h}\mathrm{h}\left(i\right)$	a	35.3	1.2	36.5	a = 0.97, b = 0.97	a = 0.95, b = 0.98	96.9	93.3
		b	2	61.5	63.5
			37.4	62.6	96.8
11	$\sum _{i=1}^9{\sigma }^{\circ }\mathrm{h}\mathrm{h}\left(i\right)+{\sigma }^{\circ }\mathrm{v}\mathrm{h}\left(i\right)$	a	6.2	0	6.2	a = 1, b = 0.67	a = 0.17, b = 1	68.93	20.07
		b	31.1	62.7	93.8
		Total	37.4	62.6	68.9
12	$\sum _{i=1}^9{\displaystyle \frac{\left({\sigma }^{\circ }\mathrm{h}\mathrm{h}\left(i\right)-{\sigma }^{\circ }\mathrm{v}\mathrm{v}\left(i\right)\right)}{\left({\sigma }^{\circ }\mathrm{h}\mathrm{h}\left(i\right)+{\sigma }^{\circ }\mathrm{v}\mathrm{v}\left(i\right)\right)}}$	a	0	0	0	a = 0, b = 0.63	a = 0, b = 1	62.6	0
		b	37.3	62.6	100
		Total	37.4	62.6	62.6
13	$\sum _{i=1}^9{\displaystyle \frac{\left({\sigma }^{\circ }\mathrm{h}\mathrm{h}\left(i\right)-{\sigma }^{\circ }\mathrm{h}\mathrm{v}\left(i\right)\right)}{\left({\sigma }^{\circ }\mathrm{h}\mathrm{h}\left(i\right)+{\sigma }^{\circ }\mathrm{h}\mathrm{v}\left(i\right)\right)}}$	a	28.3	6.5	34.8	a = 0.82, b = 0.86	a = 0.76, b = 0.9	84.4	66.3
		b	9	56.2	65.2
		Total	37.4	62.6	84.5
14	$\sum _{i=1}^9{\displaystyle \frac{\left(8\ast {\sigma }^{\circ }\mathrm{h}\mathrm{v}\left(i\right)\right)}{\left({\sigma }^{\circ }\mathrm{h}\mathrm{h}\left(i\right)+{\sigma }^{\circ }\mathrm{v}\mathrm{v}\left(i\right)+\left(2\ast {\sigma }^{\circ }\mathrm{h}\mathrm{v}\left(i\right)\right)\right)}}$	a	27.5	6.4	33.9	a = 0.9, b = 0.85	a = 0.73, b = 0.9	83.7	64.4
		b	9.8	56.3	66.1
		Total	37.4	62.6	83.8
15	$\sum _{i=1}^9{\displaystyle \frac{\left({\sigma }^{\circ }\mathrm{v}\mathrm{v}\left(i\right)-{\sigma }^{\circ }\mathrm{h}\mathrm{h}\left(i\right)\right)}{\sqrt{\left({\sigma }^{\circ }\mathrm{v}\mathrm{v}\left(i\right)\right)2-\left({\sigma }^{\circ }\mathrm{h}\mathrm{h}\left(i\right)\right)2}}}$	a	0	0	0	a = 0, b = 0.63	a = 0, b = 1	62.6	0
		b	37.3	62.6	100
		Total	37.4	62.6	62.6

Figure 4. Spatial distribution of dual-irrigation in the Berambadi watershed in 2013. The other croplands are partially groundwater irrigated in the absence of rainfall or grown under only rainfed condition.

Table 3. Total irrigated area and classification accuracy for the dual-irrigation practices in the Berambadi watershed. Where a and b are representing respectively irrigated croplands and other (rainfed and fallow) croplands.

Cropping Season	Irrigated area (km^2)	Irrigated area (%)	User's Accuracy (%)	Producer's accuracy (%)	Overall accuracy (%)	Kappa Coef.
Dual (Kharif + Rabi) 2013–14	6.2	13.4	a = 0.98, b = 0.97	a = 0.94, b = 0.99	97.2	0.94

Figure 5. Spatial distribution of Kharif cropping season irrigated croplands. The other croplands are partially groundwater irrigated in the absence of rainfall or grown under only rainfed condition.

Table 4. Total irrigated area and classification accuracy for the Kharif cropping season. Where a and b are representing respectively irrigated croplands and other (rainfed and fallow) croplands.

Cropping Season	Irrigated area (km^2)	Irrigated area (%)	User's Accuracy (%)	Producer's accuracy (%)	Overall Acc. (%)	Kappa Coef.
Kharif 2013	10.1	21.7	a = 0.85, b = 0.96	a = 0.94, b = 0.9	91.4	0.82

Figure 6. Spatial distribution of Rabi cropping season irrigated croplands. The other croplands are partially groundwater irrigated in the absence of rainfall or grown under only rainfed condition.

Table 5. Total irrigated area and classification accuracy for the Rabi cropping season.

Cropping Season	Irrigated area (km^2)	Irrigated area (%)	User's Accuracy (%)	Producer's accuracy (%)	Overall Acc. (%)	Kappa Coef.
Rabi 2013–14	10.5	22.6	a = 0.88, b = 0.92	a = 0.86, b = 0.94	90.4	0.79