In this paper, an image based approach of the water flow information measurement is proposed. Applying the image based measurement is safely and efficiently non-contact method. This paper proposes the multiple virtual water level probes (MVWLP) method which can apply in any river environment without ruler where has regular water line on the embankment. This approach mainly applies the color space adjustable technique to reduce noises and uses the adaptive edge detection to extract the water line. Then, it sets some virtual probes on the discovered water line comparing with the preset probes to measure the current water level. We convince that the proposed methods are accurate, robust and adaptable enough to overcome multiple conditions presented in the sites.