Evaluation of the Threshold for an Improved Surface Water Extraction Index Using Optical Remote Sensing Data

Table 3

Summary of the classification accuracy assessment of the AWEI threshold improvement.

Class threshold method	Threshold	Land cover class	User Accu. (%)	Product Accu. (%)	Comm. error (%)	Omi. error (%)	Total error (%)	Kappa	Overall Accu. (%)
Normal threshold	≥0.000	Water	99.82	78.07	0.18	21.93	22.11	0.876	98.17
		Nonwater	98.16	99.98	1.84	0.02	1.86
Equal interval	≥−0.676	Water	27.65	99.99	72.35	0.01	72.36	0.187	49.38
		Nonwater	99.99	37.26	0.01	62.74	62.75
Quantile	≥−0.089	Water	99.69	98.21	0.31	1.79	2.10	0.987	99.84
		Nonwater	99.87	99.98	0.13	0.02	0.15
Geometrical interval	≥−0.084	Water	99.70	98.11	0.30	1.89	2.19	0.987	99.84
		Nonwater	99.86	99.98	0.14	0.02	0.16
Natural break	≥−0.232	Water	98.56	99.67	1.44	0.33	1.77	0.989	99.86
		Nonwater	99.98	99.89	0.02	0.11	0.13